Author Topic: Rebuilding my Solar Power System after 3 years Storage  (Read 23131 times)

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Offline frackers

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #30 on: December 14, 2018, 01:44:05 am »
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)!
Robin Down Under (or are you Up Over!)

Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #31 on: February 04, 2019, 11:18:58 am »
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.



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.


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Offline WooferHound

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Going without Batteries for a while
« Reply #32 on: March 24, 2019, 07:38:06 am »
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.



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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Offline WooferHound

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using Wild Power now
« Reply #33 on: March 28, 2019, 09:25:33 am »
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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Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #34 on: April 02, 2019, 02:30:41 pm »
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.



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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Offline rossw

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #35 on: April 02, 2019, 03:26:54 pm »
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.

Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #36 on: April 02, 2019, 10:15:47 pm »
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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Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #37 on: April 07, 2019, 07:30:04 am »
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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Offline rossw

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #38 on: April 07, 2019, 08:34:02 pm »
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.

Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #39 on: April 16, 2019, 08:58:58 am »
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.



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



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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Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #40 on: April 21, 2019, 09:33:45 am »
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.



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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Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #41 on: April 21, 2019, 04:58:12 pm »
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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Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #42 on: April 25, 2019, 08:56:40 am »
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.



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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Offline WooferHound

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #43 on: April 27, 2019, 12:21:38 am »
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.



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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Offline Pete

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Re: Rebuilding my Solar Power System after 3 years Storage
« Reply #44 on: April 27, 2019, 10:15:53 pm »
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