Anotherpower.com Forum
Project Journals => Users Projects => Topic started by: WooferHound on September 06, 2018, 06:34:23 am
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Three years ago I was planning to move to a different house, so I had disassembled my Solar Power System and stored it in the shed that the gear had been setup around. So it's been 3 years and I am realizing that I am staying here in this house, and now I am putting everything back up.
The old system was arranged around a shed that was at the opposite end of the house from the location that I was actually using the power at my computer desk in the living room. The wire to carry the power from the batteries was over 110 feet long. I have re-purposed this wire to carry AC power for the computer and entertainment system. The decision was made to move the Solar Power to the other side of the house so I don't need to run another long expensive wire along the house. The main power wire will be less than 20 feet long in this rebuild. I'm already pretty far along with this project and I may be using some power from it in a few days.
Last week I built a fairly large weatherproof cabinet that will contain the batteries and electronics, plus it will be the base to hold up the first 6 of 10 solar panels. Been waiting on the paint to dry on this so I can get the panels mounted on it, maybe this afternoon.
The two 6 volt Trojan T-105 batteries were only 1.5 years old when stored in a picnic cooler. But my exwife would never turn anything off and ran the batteries low frequently. When the system was shutdown the batteries were showing signs of problems and I was trying to sell a house and did not have time to try and fix it.
Yesterday I started looking closer, Voltage measured 2.3 volts, popped the tops off the batteries and hated to see Dry Plates in all six cells. Forgot to check the water over the years. Got some filtered water and was pleasantly surprised to see that the water was actually even with the plate tops and only small parts had dried out. The cell caps had a smoky looking residue on them
Grabbed a battery charger and charged each battery individually at 6 volts and then in series at 12 volts. Still working on all that but it is a simple charger, not even one switch on it. As soon as I can get the panels mounted I will start trying to drive the voltage up even higher.
Will be working on it today and will have some pictures and a report this evening . . .
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Over the years, I have been both amazed, and confused by batteries. Some bounce back
from amazing abuse, and some die from one accidental flat discharge.
Hope yours will amaze you.
I have seen that smoky residue as well, just scrubbed it off and put the caps back. Never seems
to re-occur after that.
Good luck.
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The charger is taking the batteries up to 5.9 volts and then they drop back to 5.5 volts.
Tropical storm Gordan is wandering around in the area and keeping things a bit rainy at times. It looks like I am On Track to have a few days of No Sun after I get the panels installed.
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This project is going much faster than I thought it would, I guess it's because everything is already made. I am charging batteries now but don't have a way to use the power yet.
[attach=1]
The Solar Panels were originally mounted on the shed on the lefthand side of this picture. Charge control and the batteries were inside the shed and there were four 12 gauge wires going all the way across the back of the house to my computer desk on the lower righthand side of the place. I'm not sure why I did it that way instead of what I am doing now as everything is much simpler this time.
[attach=2]
Everything is now on the side of the house. I'm in the middle of a large neighborhood so the system is between two houses facing directly South. The main power cable to the Point Of Use will be less than 20 feet long this time compared to 110 feet from the shed.
[attach=3]
I had to spend half a day clearing this area, not used at all, only go there to cut the grass. Placed brick on the ground to help keep the wood dry then built the cabinet on top. This is everything so far, and at this point it's a stand-alone 12 volt battery charger. There will be some doors added to the front openings. In this location it does not get full Sun till 10:30am because of a nearby Crepe Myrtle tree that really needs a good trimming. The tilt of the panels is easy to adjust, but think I'll set it on the Fall Equinox September 22 and leave it there year round as these Amorphous panels don't seem to be sensitive to angle very much. There will be 4 more solar panels added on each side of the fence to help get more Sun in the morning and evening.
Might be mildly concerned about theft since it's on the ground now.
[attach=4]
The electrics are inside the cabinet. Two Trojan T-105 batteries are inside the picnic cooler providing 12 volts at 225 amphours. Still not sure about reviving these batteries yet. The cooler is propped open for Summer ventilation. The cabinet itself has plenty of airflow.
The box on the left provides fused inputs and outputs to the battery.
Center box is a power combiner with ten 4 amp solar inputs, Two 10 amp 50 volt bridge rectifier inputs and a 10 amp 1000 volt bridge rectifier input.
Righthand box is Charge control using a 2 stage Dumpload controller which is capable of about 300 watts of dumping into some 10 ohm resisters.
Still need to put a hole through the cement block on the house to get a wire through to a power distribution box so I can actually use some of that power.
Amazingly enough there are No Clouds this morning so maybe it will have something to do today ?
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Nice woof. Lots of progress.
Keeping fingers crossed for the batteries.
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Guessing that all the panels have about about 6 amps charging power combined. Monitored battery voltage all day yesterday, started at 11.3 volts in the morning and eventually worked up to 12.0 volts Max when the Sun was shining and 11.7 volts as clouds crossed over, then back to 11.3 volts this morning. So there was not any gain at all.
This morning I unhooked the series connection on the 2 batteries and connected the charging cables to only one of the 6 volt batteries. So I'll see if I can push the voltage up past 6 volts on that battery today. Would love to get up to an equalizing charge of 8 volts on these two batteries. Want to see some vigorous bubbling in there.
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I can't say I think your location of the panels will be very good for max yeild.
The proximity of the house next door looks like it will kill your winter generation and then there is the tree and the section of fence.
I would suggest you consider moving the panels to a clearer spot in the yard. The DC side is a lot less susceptible to fall off if you use suitable cable than AC is. It does not look like you are pushing a lot of power anyway so even modest cable should carry the load without too much resistance. You could leave the controllers where they are and just run a cable back to them. Looks like you have a suitable facing section of roof where you could split the panels easy west so that may be a good place to put them as well.
That would have the advantage of giving you max hours of relatively even charge as against highest peak. If you are using the power at night, always a good thing to start putting charge back in them as soon as possible. You are probably missing out on a lot of valueable amps if your panels are not charging till 10 am.
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It's been 10 days from my last update, but it has been more of the same battery revival as mentioned in my last post.
Plus have been working long hours at my job so haven't had much time to mess around with it.
So the plan has been to charge each 6 volt battery individually to try and drive that voltage up to something that I can use.
Working with one battery at a time and alternating connection to each battery every 2 days. In the beginning each battery was sitting at 5.7 volts resting. During the days the panels will drive the voltage up to 6.2 volts max. Over the past 10 days the resting voltage has gone from 5.7 up to 5.9. I have not tried to connect any loads to them so not sure about their ability to actually supply power.
When I get time I want to try some more drastic measures. I have an 80 volt transformer that has two 10 amp secondary outputs. I plan to put a single diode on the output and pulse the batteries with halfwave 60hz pulses that should be at 110 VDC peak, possibly using both secondary outputs for 20 amp pulses to try and wake them up that way.
Another thing to try would be trying to put drastic loads on them, or even pulse them with a 15000 volt neon transformer I have.
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A few dollars will get a cheap SG tester ( bulb thing with the floating stick inside).
Without this, it is very difficult to even guess at whats going on inside the batts..... I suspect not as much as we wish).
Fiendishly tidy set up there :-[
........oztules
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I can't say I think your location of the panels will be very good for max yield.
The proximity of the house next door looks like it will kill your winter generation and then there is the tree and the section of fence.
I would suggest you consider moving the panels to a clearer spot in the yard. The DC side is a lot less susceptible to fall off if you use suitable cable than AC is. It does not look like you are pushing a lot of power anyway so even modest cable should carry the load without too much resistance. You could leave the controllers where they are and just run a cable back to them. Looks like you have a suitable facing section of roof where you could split the panels easy west so that may be a good place to put them as well.
That would have the advantage of giving you max hours of relatively even charge as against highest peak. If you are using the power at night, always a good thing to start putting charge back in them as soon as possible. You are probably missing out on a lot of valueable amps if your panels are not charging till 10 am.
I guess that I didn't mention the way that this system is used.
At this time I have 150 watts of panels and this system is designed to provide 12 DC power and I use the power that way. Everything runs on 12 volts.
Radio, TV, Lights, Fan, Modem, Router, Phone Charger, Laptop, Etc.
I have a 400 watt inverter available for the refrigerator in case of a power outage. I expect that I save about $3.oo a month on my electric bill, but when the power goes out it is priceless.
So this is pretty much a Hobby System that supplies power for nonessential loads. Yes, my neighbors house is rather close to mine and the shadow of the roof peak may cross the panels for awhile at noon in the Winter, but I'm good with that and will enjoy the power that I can get. Sure, I will maximize this location as its is the best spot that I have, Trim back that Crepe Myrtle tree and add 4 more panels in better locations for morning and evening Sun.
If you want more detailed information about the components you can visit this link to the previous installation of this system in the shed.
timmythy.home.mindspring.com/re-power.htm
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A few dollars will get a cheap SG tester ( bulb thing with the floating stick inside).
Without this, it is very difficult to even guess at whats going on inside the batts..... I suspect not as much as we wish).
Fiendishly tidy set up there :-[
........oztules
Oh my goodness, why didn't I think about that, will get one of those very soon, Thanks !
When I transported the batteries from the shed, 70 feet to the new location, I was hoping that the rough motion would stir it up to make a difference but I don't think it had any effect.
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Working on the batteries for 4 days. Can Not get the voltage to go above 12.5 on this pair of batteries.
They sat all night at 12 or 11.9 volts. I hooked up my inverter and ran a 120v 100w incandescent bulb, should have been about a 10 amp battery load. In a few minutes the voltage dropped down to 11.4 volts and ran for half an hour before dropping to 11.3 then another half hour before reading at 11.2 and I turned it off. So there is some usable power but it is almost too low voltage. I don't even need a charge controller right now.
On the Other RE Forum a user talked about reviving batteries by pulsing them with 10 times their rated voltage. So that is my plan for tomorrow. I have a transformer with two 80 volt 10 amp secondaries. 80 volts AC power will peak at 112 volts which is almost 10x12 volts. I plan to halfwave rectify those outputs and feed the battery with 60hz pulses for a second or so to see if they can Wake Up some.
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might work woof, but I just had to warn you to be careful. I blew up a battery in the shop
and it can be, for lack of a better word, spectacular.
It was a poor connection spark that caused mine.
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I'm a long way away... so from here looks like a plan..... if I were closer, then maybe no so flash... but you never know.
The internal resistance/impedance of the battery and the transformer will dictate just how exciting this may get. If the battery has sloppy impedance, then the voltage may rise easily, and the current flow fairly benign, or if the internal impedance of the 80v secondary is high, then the current will not be intense perhaps... so suck it and see is a viable option.
Make sure sparks are unlikely to occur (connections into and out of the battery region),and keep a good idea of the temp rise,(battery and transformer) and it should be safe enough...... standing in the next zip code may be worthwhile too :o
A fuse some distance from the battery may be a good investment too.
Oh, and check your water level before you start this... plenty of water over the plates
..........oztules
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If you have access to an electric fence unit I have heard that they can do the job of desulphating batteries.
Like others have said be very careful with sparks while charging batteries.
I too have had a battery blow up in my face, it is very spectacular and took quite a while for a new thumbnail to grow and for my ears to stop ringing.
Good luck with the batteries, I have not had much luck myself with old batteries, They usually end up at the recyclers.
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yep, I reckon 5kv@40 amps will shake up the crystals if anything will. The best I have seen out of my fencers was 10kv@40 amps.... thats as far as the galligher tester went... it may have been more current than that, don't know.... but certainly looked nasty enough to split any molecule.
...........oztules
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In my last post I had fully intended to have a day trying to tickle the batteries back into taking a proper charge, Instead I spent 2 days getting wire into the house and setting up enough connections to use and monitor the power more easily inside.
-- Day 1 --
Hammered a Star Chisel for an hour to make a 3/4 inch hole through the cement block on the side of the house. Pulled twelve 14 gauge wires through there which has a capacity of 15 amps each. They will be used like this...
4 wires for 12 VDC power, 2 Positive & 2 for Negative. 30 amps total.
3 wires for 120 VAC power from a 400 watt inverter. Has wire for ground going outside to a ground Rod.
4 wires for charging, like pedal power. 2 pairs of wire going out to individual Bridge Rectifiers.
1 spare conductor, possibly a Ground wire.
Also ran an Ethernet cable which is 4 pairs of 24 gauge wire. Two pairs for LED Dump Load indicators and two spare pairs.
-- Day 2 --
I use this power in areas around my computer so everything mounts to my computer desk where I can reach it.
Mounted 12 VDC Distribution box with 50,000 mfd capacitor to prevent surges then 4 fused outputs.
Mounted box with 3 Cigarette Lighter outlets and a single USB output
Modified a Switch Panel and mounted it to control; Lights, Fan, Audio Amplifier, Modem & Router. Six switches leading to a terminal strip, so anything I want to hookup.
I mounted the LED Dumpload Indicators on this switchbox plus some Red LEDs to show if anything is On, showing that power is being used.
It is a lot nicer being 20 feet away from the system because it is easier and less expensive to run all the wiring that I want to experiment with.
Pictures soon, I am working today. Will play with the batteries in a coupla days.
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Lots of progress. Envious of the energy.
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Geez Woof, a star chisel, that takes me back. Surely one of your neighbours had a tungsten drill bit that would have done the job?
I once spent many days in the bottom of a well with a star chisel, making holes to put plugs of gelegnite in to blow rock out of the bottom of the well.
I understand the job, I hope the mortar in your walls is strong, and that you didn't make too many cracks in the wall in the process.
Sounds like you are having lots of fun with setting up your system. May the sun always shine on your panels.
Pete
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Geez Woof, a star chisel, that takes me back. Surely one of your neighbors had a tungsten drill bit that would have done the job?
I once spent many days in the bottom of a well with a star chisel, making holes to put plugs of gelegnite in to blow rock out of the bottom of the well.
I understand the job, I hope the mortar in your walls is strong, and that you didn't make too many cracks in the wall in the process.
Sounds like you are having lots of fun with setting up your system. May the sun always shine on your panels.
Pete
Hmmmm ... I didn't tell these stories, but since you bring it up . . .
I have a 12 inch long 1/2" Tungsten drill bit and have tried to use that bit to drill through this particular wall in the past, but could not drill through the second Cement Block layer, so I stopped and then made it work somehow a foot further away on the wall. Early in this project I knew that I needed to make this hole and did not want to buy a hammer drill just to make this 1 hole even though my neighbor has one to borrow. So the star chisel was ordered while the cabinet was being built, $22 shipping and all. The Big Box stores did not have them in stock locally.
The previously started hole was too small for what I wanted so I just enlarged it with the Chisel. The second block layer proved to be difficult again the second time and great amounts of chisel hammering were involved untill a soft layer like wood was encountered. Went inside the house and could see where the point was trying to drive through the sheetrock. Then I noticed the power was off for the computer & entertainment center.
What The Fuk, that wiring is not where I'm chiseling. Checked many things, even Pulled the Mains fuse thinking that maybe a Phase had blown, but everything seemed fine after 30 minutes looking. Went back to that one outlet that was powerless and inspected closely. It was 8 inches away from the intended hole and had a fist sized Surge/Noise power filter and a couple of multi-tap power cubes hanging on it. The vibration of the nearby chiseling had vibrated everything apart enough to break the connections. Difficult to see until I got close to it.
Where was I ... oh yeah, I was trying to pound a hole through the wall. Decided to try and finish the hole with the 1/2 inch tungsten bit mention earlier. Since I was only a few feet away from the system cabinet, I plugged the hand drill into the 400w Inverter. First time I've ever tried to do anything useful with the inverter. I was quite surprised that it was working so well with a 1/2 inch bit on concrete and in 2 minutes I had punched completely through the wall. Spent a little more time and enlarged the hole to 3/4 inch with the star drill working from both sides of the wall.
That's the story of the hole in my wall.
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Love it Woof, stories are great. Glad to hear that you managed to get through the wall without collecting any wiring or any plumbing.
Sounds like you are having a wonderful time.
Cheers
Pete
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Wokeup today and found my system voltage all the way down to 10.2 volts so I decided that today is the day to try and tickle these batteries back to life.
Removed all the system fuses and disconnected the batteries, then took them out of the picnic cooler and placed them in an open area on the ground. Got a good look inside and the plates are fairly warped and discolored. Got an 80v 10a transformer and wired a large heatsinked diode on the output making halfwave pulsed DC for the battery. Got a 16a Variac Transformer and wired it through the 80v transformer charger to the batteries in series at 12 volts. Attached a Voltmeter to the battery terminals for monitoring.
When turning up the Variac I was able to easily control the battery voltage to anything I wanted, so I dialed it up till it was reading 14.4 volts and let it sit for awhile. After 15 minutes of messing with it all, I shut it down and went to inspect it. The diode heatsink was very warm to the touch and the transformer was getting hotter than that. The batteries had many small bubbles coming to the surface, the first bubbles that I've seen since this project was started. The batteries faded back to 11.9 volts fairly quickly.
After letting it all cool down I decided to pulse the batteries without the Variac and plug 120vac directly to my 80v transformer charger. After 5 seconds the battery voltage had reached over 15 volts and then it blew the Circuit Breaker to my duplex outlet. Reset the breaker and started plugging in the power till I saw 15 volts then a quick unplug. repeated this about 5 times and the extension cord I was plugging started to get warm. Also physically kicking the batteries to shake everything up and help breakup deposits inside.
So far it doesen't seem to be having any effect and the batteries always settle back below 12 volts. Still working on it. May drag out the high voltage Microwave transformer later. If all else fails I might try a 12kv neon transformer on it.
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Worked it all day today. I have dumped a lot of power into those batteries today. Still don't think that I have made a difference. Each cell of the batteries have been bubbling at least once every few seconds. Been trying to keep the battery voltage over 13 volts but the current draw is making all the components run too hot, so I keep the Variac dialed down between 25% and 30%.
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OK , I'm declaring these batteries DEAD. Resting voltage is below 11 volts now and slowly decreasing.
I have a small 12v Lawn & Garden battery that I will try to use until I can get proper replacement batteries for this system. I got this battery from a garage I was cleaning up last year. It looks old and used but seems to be holding a charge. Just started working with it so I don't know what condition it's in yet. Was sitting at 11.8 volts when I got it a few minutes ago.
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It appears that this Lawn & Garden battery is good. It looks old and beatup but it acts just fine. Pulse Charged it up to 15.6 volts and kept it there for a couple of hours. Unplugged and it settled down to 12.65 volts. It is only a 20 amphour starting battery and old so it won't last long. Installed it into the Solar Power system and it charged right up to 15 volts in a short time. Turned on the charge controller and everything seems to be fine. Haven't had a chance to see if it has any good capacity yet, will give it a good test tonight.
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Woof, I reckon you have given that old battery every possible chance to either recover or go into orbit, it's been beaten cooked fizzed, and a good old fashioned electrocution at 80v or more.... what else can a man do??
So I don't think you will toss it out wondering if you could have done more.
It does gell with my feelings on battery recovery from the dead..... it's a lottery, no science at all, something either works or it doesn't. Any time I have tried, I have met with the same resounding success you have just displayed.... none, nix, nil.zilch etc etc.
Some other folks have been wildly successful, and I don't ......totally ....doubt them, it is just that I haven't had any success at all, and struggle to see how they have blitzed me so bad..... so your results mirror my own attempts.
Anyway, onwards and upwards, the system is getting back together, thats the main thing.
Go woof
........oztules
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New update about my Solar Power system.
I installed this stuff shortly after my last post here.
On the left is the power distribution system. The battery power comes in here and has two capacitors that total 50,000 Mfd to buffer that power and prevent voltage drops when new loads are added. Plus there are 4 fused outputs for the various parts of the system.
On the right is one of my switch banks that control my lighting and fans around my computer area. On the righthand side you can see 5 red LEDs. All of these LEDs illuminate if any of the switches been turned on, indicating that Battery power is being used. Also in with the red LEDs are 2 green LEDs that indicate when the Dump Controller has the batteries at full charge.
At the bottom sitting on my tower computer case is a 12vdc audio amplifier used for inputs from a couple of sources.
[attach=1]
That switch bank powers this Terminal Strip where all the loads are connected.
[attach=2]
There is another smaller switch bank near the chair my girlfriend sits that powers a 10w LED for her area plus some of the Mood lighting and a couple of extra switches. You can see that I have a coupla red LEDs on it to indicate if any of these switches are on and using the battery. In fact I now have created a Bus I call the Active line. anytime anything is switched on, the active buss goes high and all the red indicators on all switch banks will light up. There is a green LED on this box from another project and is not used here.
[attach=3]
All switches in this system use terminal strips for their output so I can change things easily.
[attach=4]
Then there is this triple Cigarette lighter output. I use this a lot when creating my LED projects. Inside of it I have placed a Buck Converter which powers the Triple USB charging sockets on the left of the Cigarette sockets. It set for 5v at 1 amp and will charge 1 cell phone really fast.
[attach=5]
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Hi Woof, sounds like you are almost ready to dump the grid. I have tried using large caps as energy stores too. They pack a punch if a short happens anywhere. I have two 50 thousand microfarad caps that I used to smooth a welder rectifier that I built. When I tried to strike the arc they threw a massive spark nearly stronger than the welder itself could put out.
Glad to see that you are enjoying using solar power and converting everything you can.
I use 12 volt LED bulbs at home now, ( my system is off grid) . The bulbs just look like normal light globes but use only 5 or 7 watts. They are great lights. Not like your spots though.
Pete
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I'm really enjoying all of the lighting that I've created and it works great without using much power. But I am asking a LOT from the old 20 amphour Lawn and Garden battery that is out there now. It was found in a garage that I was cleaning out for a friend. It was really dirty, looked very old and the plates were dry. Cleaned it up, put lots of filtered water in it and was surprised that it took a charge and could power stuff fairly good. Then a month later my failing Deep Cycle batteries died and this was the best battery that was available to me at the time.
There is a battery charger out there and if there is a cloudy day, I'll have to power up the charger to get going again. A 5 watt LED light pulls less than half an amp and this battery will not make it through the night with only that light on. I won't let it go below 11 volts, so when it starts showing 10.X on the meter I'll power up the charger for awhile.
Found a nice Volt/Amp meter on eBay for $7 free shipping and should arrive very soon. It will be nice to be able to see the Amp Draw all the time. There are plenty more things that I have, and want to add to this 12vdc power: Modem, Router, and Portable TV. But can't do that with this battery for sure.
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I got tired of going outside in the cold & rain to plug in the charger, so yesterday I built a maintainer that will keep the battery from going below 11 volts.
Not sure what to call this thing ... a Battery . . .
Maintainer
Backup
Protector
It is a: 12v 3a Transformer > Bridge Rectifier > .1 mfd cap, 2200 mfd cap > Buck Converter > .1 mfd cap, 1000 mfd cap > Diode > Fuse > Battery
The buck converter is set to maintain the battery at 11 volts and supply loads as high as 2.5 amps.
Now I can use all of this stuff I made without worrying about the battery. The solar panels can charge it up it up to about 12.3 volts sitting. Then power will be used from the battery until voltage gets down to 11 volts and the Maintainer will hold it there and supply up to 2.5 amps for the lights and other stuff that I want to run.
Of course the real solution is to get another Battery. Unfortunately that will have to wait till after the New Year for money reasons. Might get a used battery from the Interstate Battery store about half a mile from home.
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I've done good on 2nd hand batteries by going round the car yards and scrounging a battery "that's good enough for an electric fence - don't need cranking amps".
- The 1st one ran a discharge tester on a couple and gave me one
- the next yard gave me 2 (one good, one DOA)
- the next yard gave me a 70 amp-hr battery that looked like new - still using it on my walnut washing machine 2 years later
Over some 4 years of scrounging I now have 2 good ones, 2 others usable and 4 ready to recycle (were OK for a short time)!
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I recently got a new Volt/Amp Meter that I really like. I got it from Malaysia and it took a month to get here. Can measure up to 100 volts and 10 amps. It has LED readouts, red for volts and blue for amps with a large display making easy to read at a distance. Great quick updates to the readings about 5 times a second. cost about $7 shipped.
When I installed this system last year I was using the raw LED voltmeter in the middle. It was accurate but flashed the readings about twice a second making it a bit distracting.
A coupla months ago I got the LCD volt/amp meter at the bottom, but the display was small and then divided into 4 sections displaying Volts, Amps, Load Resistance, and a 5 segment programmable bargraph to indicate charge state. Had to have a magnifying glass to read it, but was quick, accurate and easy to hook up.
[attach=1]
The new meter was l little difficult to hookup. It had male pins and a plug/wiring harness. The provided wiring was not suitable for 10 amps, so I soldered my wires directly to the pins coming out of the back. It is very likely that my maximum loads will normally be less than 3 amps.
[attach=2]
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Have been using an old 20 amphour battery for awhile on this system and it finally stopped taking a charge, so, out it goes.
The only battery I have that could replace it is a used 7ah battery and it's just too small. I'm planning to start using a Lithium 18650 battery bank soon but won't have the parts here for about a month.
[attach=1]
Ended up making a 90,000 mfd capacitor bank to use temporarily until I have the Lithium battery bank finished. This Solar Power System already has an additional 50,000 mfd capacitor bank inside the house on the Fused Distribution system. So there is about 140,000 mfd of capacitors total buffering the power. Isn't that .140 Farad?
Voltage control is still being accomplished by the Ghurd Dump Controller set to 14.4v that was working the original battery.
Of course Capacitors don't have any real storage capacity so there is a Voltage Maintainer on it that will keep the voltage from going below 11.1 vdc. This will keep things going without daylight.
This has been working for a full day now. It's a little bit weird but seems to be working good enough to to get the Lithium Bank built. My loads are LED lights driven by buck converters, plus an audio amp and some fans, nothing that would complain about fast voltage swings.
The Lithium bank will use 18650 batteries setup in a 14-21 volt system, then using a Buck Converter to reduce voltage to 12.5 volts for Distribution and Usage.
The Bank will start out as eight 18650 batteries in Parallel making about 10 amphours, then 5 in Series for the 21 volts, 5s 8p.
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Now that I'm using capacitors for batteries, I figured that charge control isn't needed. So I turned off the Ghurd Dump controller and let the voltage run wild, slightly less than 21 volts full Sun directly from the panels.
Inside there is a 3 amp buck converter to lower the voltage to a usable 12.6 volts for use by the loads. I rarely use more than 2 amps with this system so this should work fine until the 10 amp buck converter arrives next month.
The voltage Maintainer has been raised to 13.5 volts so the storage capacitors never go below that level, insuring a good 12.6 volts for the loads when there isn't any Sun.
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I got a few parts for my future Lithium 5 series, 8 parallel 18650 battery pack. This pack will be constructed to hold 40 more batteries for future expansion. With 40 batteries it will be 21 volts and about 20 amphours. After using a buck converter to take this down to 12.6 volts working power, The apparent amphours will be closer to 28.
[attach=1]
The parts I received are JT60 - 60amp battery connectors, some JST connectors for 5s battery packs, and a Battery Monitor/Balancer for for battery packs up to 8s.
This afternoon I put together a small 2.5 amphour 21 volt battery and I'm using all of the new parts.
Was really interested in the Battery Monitor operation. It is a ISDT BatteryGO BG-8S which has many functions related to Lithium battery packs: Low Volt alarm, All battery cell voltages displayed at the same time, Bank Balancing, USB 5 volt output, and battery Type setting.
Easy to use, I have it Balancing this small bank now.
The wires coming in the bottom of the picture are coming from the outdoor capacitor bank which has the Solar Panels connected directly to them. I had seen these panels charge the capacitors up as high as 22.5 volts, but the newly attached battery test bank is only charging up to 20 volts and it is a stunningly clear day.
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With 40 batteries it will be 21 volts and about 20 amphours. After using a buck converter to take this down to 12.6
20AH @ 21V = 420WH.
420WH @ 12.6V = 33.33AH
Even allowing for only 95% efficiency in the buck that leaves you with 31.6AH.
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Thanks for the calculation rossw
After looking at this for a day and thinking about it too much, I have decided to run the whole system at the high Battery Voltage 14-21 volts, then use Buck converters at all the loads to power them.
Most of the loads are LED lights which already use buck converters with current control to drive them, so they will work on anything between 11-32 volts. A small bank of 5v USB sockets are powered with a current limited buck converter too.
The only other items of concern are a 12v computer fan, a Bank of Cigarette lighter Sockets, and an Audio Amplifier. They can all get buck converters so they work properly. The amp may possibly work OK at 21 volts.
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I thought of a small problem I will have If I run the system at 21 volts battery voltage . . .
The higher power LED lights have 12v cooling fans on the heatsinks.
Nothing a small resister won't be able to control.
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The higher power LED lights have 12v cooling fans on the heatsinks.
Nothing a small resister won't be able to control.
1. Dropping from 21V to 12V with a resistor will be a lot of wasted heat. (Perhaps not in watts, but in percent!)
2. If they're ECM fans, the electronics might not like the higher open-circuit voltage. When the electronics turn off the coils, the input voltage will rise - potentially to the entire 21V - which might prove fatal.
Either put a a zener clamp across the fan, or perhaps use a series zener of (21-12 = 9V) to wash off the extra 9V or so. A 1W 9V zener might just about handle a 100mA fan.
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Still running without batteries using capacitors instead, with a voltage maintainer that keeps the voltage from going below 13.5 and a buck converter to make a working voltage of 12.5.
I finally got all the parts in to build two Lithium Ion 18650 battery banks.
Pictured are the parts to make a 5s-8p battery bank.
[attach=1]
10 battery holders that hold 4 cells each, arranged into the final shape of one of the battery banks.
10 amp Buck Converter
20 amp Charge controller with lithium battery protections
BatteryGO monitor and balancer
200 wired fuses, 5 amps each for individual cell protection
[attach=2]
The battery holders were not designed for the Protected cells that I have, so the batteries fit a little bit tight in there, but I believe it will end up working out OK.
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So I'm having a little trouble trying to figure out how to mount these battery holders down properly.
They will be mounted on some 1/4 inch thick plastic sheets.
[attach=1]
There are screw holes under the cells but there is not any real sunken area for for the screws to sink down into and would keep the cells from fully seating into the slot.
Thought I would bend out the little metal tabs and Glue or Tape the holders in place, but the metal is very hard and brittle and it breaks when trying to bend it.
Possibly drill holes in the plastic that the metal tabs would go through, but then the wiring would be under the plastic and I prefer not to have wire under the battery bank.
Thinking about some system of tie wraps, or possibly some metal or plastic hold-down pieces that would bolt through the base sheet.
Maybe I can find some small screws that would work using the holes under the cells.
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Tested some screws from the hardware bin and, I think I found a winner . . .
I ordered some #4-40 Nuts and a couple of lengths of 4-40 flathead screws.
From New York so, maybe a week ?
That should be everything needed to put together Two battery banks, 5 Series 8 parallel, 40 batteries each.
Right now I only have enough 18650 cells to fill one bank but planning to add more as they are available.
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Got another cool delivery of some electronics modules. This stuff is getting so cheap and small, all of these modules cost about a Dollar each. But there are some occasional bad modules, I think these things are just slapped together and Quality Control is up to the End User.
[attach=1]
top left
10 - Lithium 18650 Charger Modules. For charging only, no discharge protections. Got these to make a 4-cell battery Charger
top right
5 - Charger modules that have Lithium discharge protection. Will probably use these for small solar single battery projects.
bottom left
5 - Stereo amplifiers, 3 watt per channel class D, 5 volt. Just could not resist getting these, I've got a lot of ideas for them.
bottom right
10 - Mini Buck Converters, 23 volts max input, 1.8 amp constant 3 amp surge. These are so small, almost difficult to solder to. The component that is the coil also contains the synchronous rectification circuitry to help make it that small, it will sit on top of my thumbnail. Got these for when I start running a 21 volt system voltage taking some smaller stuff down to 12 volts like the fans on the heatsinks that are cooling the LED lighting.
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The Mini Buck converter has been sitting here on my desk for a coupla days now and I'm so impressed with it's size. Seems to be the same size as an LM-317t.
[attach=1]
Have not had the chance to hook one up and test it yet.
I am working so much that I can't get anything done . . .
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Great to see you having so much fun Woofer.
It is amazing how many of those very small pre built modules are available.
I have used thermostat modules to measure the temperature of my solar hot water and my car engine temperature, they cost me about $6 each including the sensor.
It looks like you are enjoying playing around with your solar system. It will be interesting to see how it all works.
Cheers
Pete
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Oh Yeah , I'm having fun buying stuff and posting pictures of it
but
I am working so much in the last coupla weeks that there is no time for sleeping
Looks like it is slowing down enough for me to start drilling holes and making stuff
A grocery bag at my feet has all the parts to make the Lithium Battery Banks
and
I'm anxious to convert the system over to 14-21 volts operation
plus
the yard needs mowed, dogs need played, have new tires and tubes to go on the bike, etc . . .
[attach=1]
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I am working so much in the last coupla weeks that there is no time for sleeping
(Attachment Link)
My work schedule has not been any better. I only have a couple hours freetime daily and then stuck at work for the remainder of the day. Today I will be stuck in Dance Recital Hell for 14 hours, and this is the 4th day. There should be over 1200 people in the theater, 90% of them will be girls of all ages, so there is some pleasantness. Barely had enough time last week to build that Lithium 18650 Charger.
I am still focused on building a couple of 18650 battery banks and converting the system over to 21 volts.
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Finally got a few days off and built two 5s 8p battery banks. Put the finishing touches on it this afternoon and went ahead and hooked them up to the system and seems to be working out very good.
[attach=1]
These are built onto some plastic that is much like 1/4 inch thick truck bed liner. The Check & Balance wiring comes off the top, the Charge & Discharge wiring comes off the bottom. They are designed to stack but will be used on their sides.
After I built the 18650 charger a month ago, all the batteries were topped up to 4.2 volts. Today I tested them and sorted them all by voltage High to Low. When putting them into the battery holders I the series rows with the high volt cells and worked across ending with the low volt cells, so each parallel section has a mix of low to high volt cells. After a month sitting, the cell volts varied between 4.10 - 4.18, not a big difference. when installed I will put half the batteries in each bank so they will have more even loading.
[attach=2]
Every single cell has it's own dedicated 5 amp fuse to prevent disaster if any cell shorts or goes Reverse Polarity. The battery holders were not made for these longer 18650 cells originally deforming in order to accommodate the batteries. I just used some pliers on the Terminals and squashed them enough to work great fully loaded.
[attach=3]
Here is the terminal strips that will distribute the Negative and Positive power Ins and Outs. The yellow XT60 connector is part of a temporary setup to allow me to plug this into the system from here inside the house for testing.
[attach=4]
This terminal strip is the Check and Balance connections. For testing it has two JST 5s test and balance connectors on it, one is plugged into the BatteryGO monitor/balancer, the other is for the charge controller which is also a balancer. Once installed there will also be another set of wires going into the house so I can use the BatteryGO monitor in there too. In the picture the readings are ...
20.36 volts total
19 mV difference between the lowest volt parallel bank and the highest
97% battery capacity
4.067, 4.064, 4.083, 4.066, 4.081 - individual Parallel bank voltages
It's all on my desk here, hooked up and powering the system. seems to be some good stiff power. Getting dark outside so I'll be looking at it closely over the next few hours to see what it's got ?
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Yesterday I moved these two battery banks into the cooler that they were designed to fit into. At this time there are 9 parallel battery sets with a capability of 16 Parallel and 5 series making an optimistic total of 21 volts at 40 amphours if filled with batteries. This will all be reduced to 12 volts or less using buck converters on every individual load, so there will be some amphour gain there.
[attach=1]
I've been using this bank for 2 days now, the first day was on my desk where I could check on it frequently, and then all yesterday installed in it's permanent location under the solar panels outside.
When I was running on Wild Power using Capacitors instead of batteries, the highest voltage that the solar panels could achieve without load was 20.5 volts. Now with this Lithium Bank the highest charge seen so far is 19.1 volts, so it will likely be difficult to charge much higher using these panels. I've got 5 more of these panels that are New Old Stock and plan on adding them after getting all this stuff converted over to work on 21 volts.
This morning I woke up discovering some strange voltage readings, after some checking around I'm seeing that the Charge Controller/Balancer seems to have Cut Off. It's designed to cutoff for for the following conditions...
Over charging detection voltage: 4.250±0.040V
Over charging recovery voltage: 4.190±0.050V
Over discharge detection voltage: 2.800±0.080V
Over discharge recovery voltage: 3.000±0.100V
This is an $8 charge controller, a small PCBoard without any adjustment or indicators. I can work around it, but obviously need a better one.
Fortunately the Balance wiring is run inside too, so the BatteryGO Monitor/ Balancer can be used anytime for close inspection.
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I am in the middle of another 4 days of Dance Recital Hell, worked 16 hours yesterday and should be 14 hours today and tomorrow.
The system seems to be working fairly good. In the last post, I was complaining about the Charge Controller in Cut Off, but after a couple of days of observation, it seems to be working as advertised and cutting off properly if any Parallel bank gets below 2.8 volts. Then it waits till all 5 banks are above 3 volts before restoring to normal operation.
Seems that I may have made a Cell weak by accidentally putting it in Reversed Polarity and that bank of 9 cells shows a difference in the readings.
Otherwise I\m real happy with the results.
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Sorry for your work schedule. That can get old real fast. I was in a similar situation several years back and it isnt fun.
Proud of you for taking the pain to make these cells work for you. I am actually looking into 26650 cylindrical cells for the car project. I can cut the new cost of LFP in half by going that route over prismatic (plate pkg format). Of course there would be lots more DIY time involved, the benefits would be cheaper, shape configuration and voltage configuration is customizable. The payback even with solar charging is pretty meager like several years to return any investment on $980 of batteries = 400 cells = 4kwh LFP. the catch is it would take some time, materials and spot welder to connect all those cells. I didnt catch how you connected cells? High power solder iron to minimize heat transfer can work i guess. Good project i love the efficiency of lithium, an electron charged is an electron available later :) For smaller systems or battery powered loads it really shows up!!
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LightHunter >> I used battery holders and just snapped the cells in there, No Soldering, super cheap and very flexible.
I have converted totally over to 21 volt lithium power now by removing a Buck converter that was holding the output voltage down to 12.6. But it looks like my 21 volt solar panels will only push the charge up to about 18 volts max (3.6v per cell), my BatteryGO Monitor says that is only 8% full. Today I will wire the panels in series to see if I can get them to charge up any higher. This will lead to more problems eventually as it will then be over 40 volts for charging the 21 volt battery bank.
The batteries don't really have a Charge Controller right now. It's really a 5s Protection and Balancing board that will has a
discharge cut-off if a cell goes below 2.8v or 14v for the full bank
Overcharge cut-off if a cell goes over 4.2v or 21v for the full bank
Max Balancing Current is 42ma
So if the Overcharge cut-off Kicks-in when it charges up to 21v, The the voltage on the input would become Open Circuit at 42v.
I still have devices connected that don't want that high voltage. They are switched and I have tape tags on the switches that shouldn't be used until I can deal with them individually.
I've tried using 2 of those super small Mini Buck Converters that were rated 1.5 amps. One was used on a red LED string 5 in series and adjusted to 9 volts at 20ma and it is working great. Tried to use one of them to power a 12v Muffin Fan rated .6 amp 7 watts. The Coil on the converter got hot to the touch and it quit completely after about a minute. Ended up using one of my regular 3 amp converters without problem.
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LightHunter >> I used battery holders and just snapped the cells in there, No Soldering, super cheap and very flexible.
Ahh, yes, that is perfect solution for your application!!
I have converted totally over to 21 volt lithium power now by removing a Buck converter that was holding the output voltage down to 12.6. But it looks like my 21 volt solar panels will only push the charge up to about 18 volts max (3.6v per cell), my BatteryGO Monitor says that is only 8% full. Today I will wire the panels in series to see if I can get them to charge up any higher. This will lead to more problems eventually as it will then be over 40 volts for charging the 21 volt battery bank.
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Werent you using buck regulator to downconvert voltage from panels? If not, thats your solution, you can even modify them to do mppt, seems like someone here has done that if i remember right. Or if you have to buy one anyway why not get an auto buckboost model and then put your panels all in parallel again. It may come out more efficient since the volts wouldnt have to be boosted or bucked much.
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Werent you using buck regulator to downconvert voltage from panels?
If not, thats your solution, you can even modify them to do mppt, seems like someone here has done that if i remember right.
Or if you have to buy one anyway why not get an auto buckboost model and then put your panels all in parallel again. It may come out more efficient since the volts wouldnt have to be boosted or bucked much.
Since I don't have much battery capacity I can drain the charge to nothing too easily, plus going a week without the Sun is common around here. So I made a voltage Maintainer which uses Mains Power to keep the voltage from going below a set point, protecting the batteries and allowing me unlimited use of the system. This uses a 12.6v transformer which is about 18vdc after rectification. That is where I'm using a Buck Converter, at this time it is set to 14v (2.8v per cell) for the new Lithium power banks.
YES , that is a great idea to wire the panels in parallel again and use a Buck/Boost Converter to push it all toward the 21v target. In fact I ordered one last night after I saw your suggestion. It is rated 7 amps, 10 peak. Should be here within a week. Was a little worried how well it will work with raw Solar Panels on the Input. It also has Current Control, but probably won't be needed.
Yesterday morning I did wire the panels in Series. There are 6 panels, 21 volts open, about 1 amp each. It greatly speeded up charge time but seemed to top out at 18.4 volts, battery monitor reading 18% full. It was a clear day under Hazy Sun and I was keeping all the loads off.
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Remembered that I already have a 6 amp Boost Converter and decided to go ahead and use that since Boost is all that will really be needed.
Rewired all six panels back to Parallel connection, Set the boost converter to 21.1 volts output and wired it between the panels and the batteries.
Today is totally Cloudy with 4-7 inches of rain forecast over the next week, so I probably won't see any results for awhile.
But , I wonder . . .
Until the batteries reach 21v Full Charge, won't the Boost Converter be heavy loading the panels down to some low unusable voltage that can't be Boosted ...
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Cloudy all day yesterday, but got a few hours of Full Sun Today around Noon.
No , a Boost converter, directly connected to raw Solar Panels, will not charge batteries.
It may possibly work using Constant Current mode.
Going back to pairs of my solar panels wired in series. 3 pairs in all totaling 40 volts at 3 amps.
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Hi Woof, just wondering why you chose such a high tech approach to your system.
I would have thought that going down the 12 volt battery bank road would have saved lots of complicated electronics.
It would be interesting to know why you chose a 21 volt battery bank, and why you wanted to use boost and buck converters.
I come from the Keep it as simple as possible camp, so run 12 volt batteries, 12 volt lighting, 12 volt power wherever possible and an inverter for 240 volt stuff. Has worked fine for me for the last 40 years of being on solar power.
Anyway it looks like you are having fun so keep on grinning
Pete
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I had explained it a little bit earlier when I said . . .
I have decided to run the whole system at the high Battery Voltage 14-21 volts, then use Buck converters at all the loads to power them.
Most of the loads are LED lights which already use buck converters with current control to drive them, so they will work on anything between 11-32 volts. A small bank of 5v USB sockets are powered with a current limited buck converter too.
The only other items of concern are a 12v computer fan, a Bank of Cigarette lighter Sockets, and an Audio Amplifier. They can all get buck converters so they work properly. The amp may possibly work OK at 21 volts.
I am up early and actually have some time so I'll ramble on a bit more.
My Lead Acid batteries had all died and I was looking for some replacements. Was pricing more lead acid plus looking at the future for batteries so was pricing Lithium batteries too. After learning more about Lithium batteries, I decided that even with the high prices there were too many good advantages with Lithium. Lead Acid batteries didn't make any since anymore so they are out and now moving on to the future.
Lithium Cells are 3-4.2 volts so it is hard to make a decent 12 volt battery with them. Five of them in series is 21v full charge and exactly fits in the Picnic Cooler that my Lead Acid batteries were in. Not to mention that the solar panels are about 21 volts too.
In the beginning I was going to run a high battery voltage and use One Big Buck Converter reducing everything down to 12.6 volts. Looking at my system I was seeing that most of the loads are LED lights which are Driven based on Current, so they already had Buck Converters with current limiters and could handle 11-32 volts. So if I used the One Big buck converter method, then the power to the LED lights would be going through 2 buck converters losing over 5% each time. That is the main reason for running a High Voltage and dealing with it at the load later.
A friend of mine gave me some Laptop battery banks, I broke them open and recovered over 40 batteries. They seem to be in fairly good condition. I enjoy making stuff, so making the battery banks and getting all this stuff up and running, then using it in real life is really fun to me.
Yes I'm grinning everyday . . .
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When I changed my panels to Parallel doing the Boost Converter experiment, I blew the fuse that connects to the batteries.
So I do Not Know if that Boost converter would have worked.
It was discovered minutes ago when I was restoring the panels back into Series connection.
I saw the spark but didn't think it would have blown the fuse.
May try it again later but it's 20 minutes of tedious work in a cramped space.
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oops, i forgot to mention buck and boost converters (at least the ones you are working with) are not meant to connect to a battery since they often use synchronous rectification for efficiency reasons, therefore an external output diode is needed between the output and the battery. Some mfgrs ship a slip of paper with them warning of this. The diode will prevent the short circuit backflow current from battery through the fet when it is powered off.
I do agree with Pete but i also enjoy doing things differently for fun like you Woof.
The boost converter current control has to be modified to regulate panel voltage, thus you end up with your very own homebuilt mppt... well close enough to it anyway. Actually temp compensated voltage control of panels gets extremely close to true mppt. To test it out you could add the diode and adjust the current limiter for full sun mpv of panel and it would work well as long as full sun on the panels.
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Oh Yeah, I have a bag that is a buck converter Graveyard. Blew a couple with Reverse Polarity and blew a few discovering that it's not a good idea to put large capacitors on a converters output because of the backfeeding voltage when turned off. I think I'm OK in this situation. The Solar panel power all goes through Diodes before being combined, then run through a buck converter and a fuse before going on to the battery box.
I would like to know more about the setup you are describing using a Boost Converter as an MPPT. Most of my Boost/Buck converters have Constant Current Control.
Tried to do a search of this site but the Search Box at the top of the page doesen't work anymore.
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In case you haven't seen this, this is the generalized circuit to to convert any converter to power point. My favorite is these 30-72V 150W 15A converters for $5 that produce 12V exactly. They can honestly produce 5A all day and several can be put in parallel Easy to boost up with a couple diodes in series with the 12V zener. One of the last converters that is easily modifiable. Interesting design that uses the switcher chip as a high side driver. An opto provides feedback and is easy todrive from external sources without conflict. It fakes the converter into thinking there is an over voltage condition and shuts it off. I use one on my 60V array to maintain a battery set to 14.5V (not 20V) which powers a $4 charge controller. The rest of the panel power goes to heat water. Yup, isolate with a diode if connecting it to battery directly.
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Eidolon, good to hear from you! You are a genius. I did by the way finally take your suggestion and get into arduino programming this last winter. It is a blast. I still cant believe how powerful the nano is and c++ in some ways is excellent for automation programming. In other words, i almost prefer it over plc programming now :).
Thanks for posting the diagram on the converter mod! I cant wrap my head around how this works (ive not used TL431). To me, when panel voltage goes above preset limit, the 431 conducts, sending voltage to the vsense shutting down the buck or boost converter. This would be the opposite of what we want. When panel volts goes too high, we want the vsense to go lower and run the converter harder. Maybe thats they way it works and im missing something.
I was thinking of the inverting 741 op amp voltage comparator. Normally, i dont want to disturb the original voltage regulation so i leave that alone and modify the current limit input to the converter. Either way if done right, it will work perfectly as you say!
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The TL431 is operated in a way that is different from usually seen. AT high pv voltages it shunts the voltage to common and the buck converter operates normally. The diodes and LED form a zener that provides an offset to that voltage sincr the TL431 can only saturate to about 2V at best. It is best to keep saturation to about 3V. A transistor or FET could be used just as well in the circuit but are prone to drifting with temperature. It might be easier to visualize the circuit with one of those in it. Certainly an op amp or comparator could be used and then temperature compensation for panels added.
I've promoted a form of linear programming for the arduino where everything id just done in sequence and each line stands on its own. Nothing but IF statements and the ever popular MAP. It is a little slower, but much easier to understand. Face it, 99.99% will never become "real programmers". I am frustrated with all those who try to show how smart they are with little programming tricks making programming seem like an impossibility. I think this discourages a lot of people who could better manage their energy.
Have you seen my water heating circuits? One is NANO. The other is a realy easy circuit that allows the heater to be connected in parallel with the panel array and harvest any excess energy not used to charge batteries.
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"AT high pv voltages it shunts the voltage to common and the buck converter operates normally."
Ahh, yes now it makes sense, thanks for the explanation.
"I think this discourages a lot of people who could better manage their energy."
For sure, yeah they do put people down over on the arduino forum. Its kinda like a grade school environment sometimes :(
I was especially surprised the IDE is not hard to use and makes debugging the program much easier than i remembered, (i took a pascal programming class years ago), c++ actually has many similarities. Im not good at it by any stretch but i can get a task accomplished tho it be the long way. Actually got one of those cheap hobby servos mounted in a 3D printed frame with a needle valve giving me high resolution modulated propane burner control to the degree. That option costs quite a bit in a purchased appliance. Of course all the pre-made libraries simplify programming a lot.
"Have you seen my water heating circuits?"
No im guessing you posted somewhere, I will have a look. I cant say as im doing it very efficient. I just matched array to the element in full sun and when its not putting out a lot (clouds etc) i switch the array over to the 2nd input of the grid tie mppt. I hafta use make before brake timing of relays or the 300vdc gets real rough on the contacts :)
"One is NANO, the other...."
Thats interesting, i tried, paralleling two microinverters the other day, they were identical but one dominated the other throwing off the tracking voltage fairly bad.
Woof, please keep posting your progress. Hopefully some of this will help. You could even control your boost converter with arduino, tho might b more than necessary.
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When time eases up I'll do a long series on the discrete water heater board which is really cheap. I'll let this be the depository for the build.
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That's essentially the classic "pseudo mppt" design. Drift however is almost a moot point, as none of these circuits actually "track" actual power. The PV drifts more than the components in the control ever will.
Anything that "OR's" the input and output voltages and pulls the PWM of the converter back when output voltage is hit or when input voltage falls below threshold accomplishes the base functionality... Much better than direct connection or a simple converter... But not as well as a true tracking scheme that hunts for the sweet spot periodically.
As for the TL431 implementation, yep sometimes you gotta get crafty hehe... That said, yes, a TL431 and an opto work well in tandem on this, and the isolation allows for super simplicity on literally any converter topology (no jumping thru hoops, just have the transistor side tug on the Vfb pin all but directly). The most stable version of it I've messed with involved a TL431 on either side into a relatively low impedance divider to set up the Vfb.
Either way, always interesting to see another version of this circuit... They're very useful where the cost (or parasitic nature) of a true MPPT can't be justified.
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It is not quite like that. A lot od MPPT is just crap and doesn't really operate at the true power point. As there is a bypass diode about every 10V on a panel and I've seen controllers sync to lower voltages and stay there in a shading situation even after it passes. One of my MPPT controllers has a micro monitoring the panel voltage and when it drops low for a period of time it disconnects the panel to reset it. Immediately higher wattage and voltage. MPPT is solar for muggles so they can connect any panel to any battery and not know anything. When heating water, voltage is everything. Constant voltage ends up just as good as power point at a lower voltage. Constant voltage can track.
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Building and installing my two Lithium Power Banks.
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I'm still having trouble getting my new Lithium Battery Bank to take a full charge. When Full it should read close to 21 volts, the highest I have seen it is 19.5 volts (3.9v per cell) which is only 25% according to the BatteryGO monitor.
For the last 2 weeks I have left the 6 Solar Panels in Series Pairs. On a Sunny day with heavy haze the total Panel output was measured open circuit 42 volts at 2.5 amps. The battery bank should be around 20 amphours. Right now the panels are connected directly to the battery bank, bypassing the charge protections. Haven't messed around with the Buck / Boost converters again for charging. Have been looking at some small MPPT controllers.
I have fully converted the system to work at any voltage between 12 & 22 using Buck converters to control the voltage or current for every individual load.
My Audio Amplifier is the only item that is running straight off the battery, it will work up to 25vdc. I made it from an Amp Module and is a really beefy little thing at 15 watts per channel. Added a green indicator light to it while I was inside it to check it's voltage capability. It sounds louder and cleaner than ever running at the higher voltage.
[attach=2]
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I have a couple of flush mount ceiling LED lights that work off those same boost converters. The commercial lamps are so cheap now. I just rip out their inverter and put one of these in. They normally work on 41V, but are more than bright enough at what these put out.
I just got a small stereo that has a 120V wall wart like converter built in. At 50V panel power it will run. It does take about 15 seconds before it will start up. Need to change that 2 meg startup resistor to 100K.
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Hey Wooferhound!
How goes the battery charging?
You probably have it humming along by now.
Anyway, best wishes on your system's success!
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Hey Wooferhound!
How goes the battery charging?
You probably have it humming along by now.
I have been feeling a bit slow lately and lost a lot of energy and motivation, to the point that I didn't want to do anything. Not sure about what my problem is, maybe Thyroid or High Blood Pressure. Well that is over now and I'm feeling more pushed to get things accomplished.
But old age is catching up to me. I'm 62 years old and and my ankles, knees and hips are starting to go. I was riding my bicycle almost exclusively for the last couple of years, but last month I bought a small cargo van that was built to be a Postal Delivery vehicle. The bike doesn't get much use now and I'm starting to gain a little weight. One thing that I noticed was that I never got sick during the time that I was riding.
So what I'm trying to say is that I haven't done anything to my Solar Power system since I finished converting everything to run on the odd 21 volt battery bank. But the outdoor temperatures are sometimes going below 90F - 32C degrees and I'm feeling better so it's time to Get Back To It !
The the 5S 9P Lithium battery bank has been only charging to a max of about 19 volts over the high Sun Summer months. The Solar panels have been set to the Spring/Fall Solstice angle which is coming up soon on September 23rd 2019, so the Sun angle will be great for a coupla months. It has been working better too. In the last week I have seen it charge up to 19.5 frequently and over 20 volts a few times. This is plenty of power for my small hobby system since I rarely use more than 1 amp load for over 10 hours.
Now I am a little bit concerned cause it is working better. It was working so poorly that I never bothered to add a charge controller, but there is battery Overcharge Protection which will disconnect the battery if any cell goes above 4.25 volts. If that happens then the system will jump up to the 42 volt Solar Panel voltage which is more than any of the Buck Converters are rated for.
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Well Well . . .
It has been a clear cloudless sunny day and I am getting a 20.6 volt (4.1v per cell) reading on the battery bank. The battery monitor shows 100% charge with a 70mv difference in cell charge.
Will be drinking beer tonight and checking out how much power that I can store now.
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I figured out that I just need a second Charge/Discharge Protection board, also does balance.
Will charge the Battery bank through one protection board which will use the Overcharge protection and cutoff the panels when charged.
And discharge through the second protection board which will use the discharge protection and cutoff the batteries when discharged.
Ordered a second identical protection board as the on I'm currently using which should control everything properly.
Plus they both do Balancing, so the single board 60ma balancing will double to a more appropriate 120ma balancing current with both protection boards.
https://www.ebay.com/itm/5S-20A-w-Balance-Li-ion-Lithium-18650-Battery-Charger-BMS-Protection-PCB-Board/264077586312?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649
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Woof... Man... Seriously... Not trying to rain on your parade...
But in a nutshell dude, you scare the crap out of me.
There's so many things to address, but I'll keep it simple and to the point for now, and go after the worst.
1. I hope it's just your use of the terminology but the P and the S are *not* interchangeable in their order. 5S9P is *not* the same as 9P5S, they represent two radically different animals, despite having identical characteristics at the main terminals. I hope for your sake you're actually employing the latter.
2. 70mV is a LOT of imbalance cell to cell... Toward the middle of the SoC curve this represents not only non-trivial but *significant* differences.
3. #2 is not surprising, as you would appear to have randomly mixed cells from countless sources, with different ages, cycle histories, and other critical considerations such as abuse (at either end) and so on. This is an annoyance with most battery chemistries. It's downright dangerous with Lithium NMC.
4. YouTube doesn't capture the potential when a cell gets a hair and decides it doesn't want to play nice anymore. Ask a buddy of mine that once viewed them in the more lax sense you appear to. Somehow he managed to get an "annoyed" RC pack outside before it took anything with it, but it certainly wised him up on handling and other important conditions like maximum and minimum voltages, what balancing (or lack of) can really imply, and what an irritated lithium cell is capable of. He didn't "hear" what YouTube had to offer on it prior to his experience. It took an up close personal event to teach him the lessons that a screen simply can't capture. Ask him if you don't believe me, I'm sure he'll be glad to tell you the story. That was 3 series cells. Imagine what you've got going getting irked.
I *strongly* encourage you to take a single cell, place it in a completely safe environment, and push it to the limits as a test to demonstrate in person what actually happens when these cells get mad. Make sure you catch a whiff of the fumes as well... That's a fair part of the experience. Then remember that neighboring cells within a certain distance will be affected by intense heat, causing a chain reaction. Trust me, it's not something you want to deal with on a large scale level unprepared.
I don't want you to take me wrong. I personally *love* lithium... But the NMC variety (most common 18650 cells) are nothing like any other chemistry in terms of their demand for respect. I can't emphasize this enough. They're a beautiful thing, with a lot of potential. Unfortunately, for as much bad as good, when mistreated.
Voltage limits (particularly the lower end) tend to be taken "grain of salt"... With overcharge getting the majority of the attention for someone just going in. When in fact while over voltage can and will indeed set one off, overdischarge is the monster lurking in the shadows... The cells change (dendrites namely) in overdischarge conditions, leading to a short at some point in the future... This unknown is primarily why BMS systems *permanently* disconnect a pack from the terminals in commercial products... It's simply *not safe* to EVER charge an overdischarged cell, ever again.
Just looking out for you, as well as your readers. I'm all about the experimentation... But please... Be safe about it. This protection and balancing stuff should *never* be any kind of "afterthought"... Not with these...
Carry on man... Be safe.
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I'll second that - I do this stuff for a living and even with a very clever chip like the BQ769x0 series of BMS from TI (which does over & under voltage, over & short circuit current protection) its still over 1000 lines of 'c' code to handle all the cases, 90% of which is associated with charging.
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Somehow the pandemic has increased my income a littlebit, so I've been Upgrading my Solar Power system. I'm doing more work on it this weekend and I'll start a new thread and describe it better with pictures.
The Highlights include . . .
-- 80 all new Lithium Ion batteries, Was using recovered laptop batteries. Every slot has been used in the battery banks that I made. This gives me a total of 21 volts at 55 amphours.
-- Fully programmable Charge Controller to better control discharge and charging limits, Plus a fancy Active Bank Balancer.
-- Modern Polycrystalline Solar panel that pushes 9 amps at 37 volts. This will replace the Anamorphous Harbor Freight panels I've been using for more than 10 years and only producing 65% of original capacity.
Adding the panel this weekend and will start a thread about the New Setup . . .
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This Thread has been continued here . . .
https://www.anotherpower.com/board/index.php?topic=1389.0 (https://www.anotherpower.com/board/index.php?topic=1389.0)