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Renewable Energy Questions/Discussion => Renewable Energy Q&A => Topic started by: WooferHound on December 26, 2018, 10:32:08 am

Title: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on December 26, 2018, 10:32:08 am
For the last year I have been playing a Lot with some Lithium Ion 18650 batteries. Charging and then using them in some of my recent projects. Everytime I mention Lithium batteries, people instantly mention about how dangerous they are because the Electrolyte spontaneously catches fire when it comes in contact with moisture, including the small amount of water in the air. These concerns are important and I will try to summarize the key points here...

Do Not Exceed 4.2 Volts or there will be Fire
Do Not Discharge Below 2.5  Volts or you will damage the Cell
Do Not Charge or Discharge the battery faster than Half of it's capacity
Do Not Short-Curcuit or there Will be Fire
Use Balanced Charging. Lithium Batteries in Series do not remain Equally Charged and must be Maintained Individually to keep the Charge Equalized
Do Not Charge a cell that is below Freezing Temperature, Causes an Overcharge Condition
It is also good to keep them Cool as possible and Protect them from Physical Damage

So if you are only using a single 18650 battery, with low charge/discharge currents, and stay between 2.6 volts to 4.1 volts (hard limits), you will have a lovely experience.
It acts much like a large capacitor and as long as you watch the voltage limits it is a happy playground to play in.

Here is a Dual 18650 charger I made using a 6 volt center tapped transformer, very few parts and charges the batteries up between 4.0 & 4.1 volts over a 6 hour period. There are some Push Terminal strips on there for charging old Cell Phone batteries. I have been putting 1/8 inch jacks on these projects to charge them up with, not the best choice because the plug has exposed power but I have a lot of them.
[attach=1]


Purchased twenty 18650 Holders to make stuff with, mostly lighting. The item at the bottom is a 12 volt battery pack using 3 battery holders glued together and a wire ending in a standard 12v connector.
[attach=2]


There is solar lighting on my bicycle and there is an 18650 battery in the back of the solar panel there.
[attach=3]


So far I have been charging the batteries independently and then replacing them into the devices that they are being used in. Now I want to go a step farther and make devices with internal batteries that can be charged, plus adding protection from over charge/discharge.
If you are only using one 18650 battery this is very easily done with a TP4056 Charger Module which allows you to charge an 18650 from any 5v USB source and provides over charge/discharge protection.
https://www.ebay.com/itm/5pcs-5V-1A-Micro-USB-18650-Lithium-Battery-TP4056-Charging-Board-Charger-Module/222579681057?hash=item33d2c86721:rk:1:pf:0

If you want to charge these batteries in series it gets a little more complicated because the battery voltage between cells must be kept balanced in addition to the over/under voltage protection. I have not made anything yet, but this seems to be the best solution for using and charging series lithium batteries in the device.
Use a MAX745 charger module to control the battery charging for up to 4 batteries in series. This will take up to 20vdc for charging and convert it to what the battery needs. It also allows you to control the max battery voltage and the charging current.
https://www.ebay.com/itm/MAX745-4-2-4-35V-1-4-Packs-Lithium-Battery-Charging-Board-Voltage-Current-adjust/111825916930?hash=item1a09581402:g:N2kAAOSwcdBWSogV:rk:2:pf:0

Then your battery pack needs a Protection/Balancing Board to keep the batteries healthy. This board needs to be made for the number of batteries that are in Series ( 2s , 3s or 4s ) and the amount of Current you expect to use from the batteries. This is called a Battery Management System or BMS.
Here are some examples ...

2s
https://www.ebay.com/itm/7-4V-8-4V-2S-PCB-Protection-Balance-Board-For-18650-Li-ion-Lithium-Battery-Cell/233006225988?hash=item364040da44:rk:1:pf:0

3s
https://www.ebay.com/itm/3S-25A-Protection-PCB-Board-w-Balance-BMS-for-18650-Li-ion-Lithium-Battery-Cell/173647618112?epid=2118855608&hash=item286e346040:g:~S4AAOSw6jJb8V2A:rk:2:pf:0

4s
https://www.ebay.com/itm/4S-14-8V-30A-PCB-BMS-Protection-Board-Charger-18650-Lithium-Battery-Cell-Balance/232966966020?epid=586125349&hash=item363de9cb04:g:~voAAOSwqLRcHEue:rk:3:pf:0


Here is some good healthy reading from the Battery University ...

Charging Lithium Ion Batteries
https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

Prolonging Lithium Battery Life
https://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: ClockmanFrance on December 26, 2018, 01:20:19 pm
Nicely written post 'WooferHound'.

I love real empirical evidence.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: frackers on December 26, 2018, 07:47:08 pm
For single cells I've found that a USB charger like these is ideal
https://www.aliexpress.com/item/Free-Shipping-10pcs-lot-5V-Micro-USB-1A-18650-Lithium-Battery-Charging-Board-With-Protection-Charger/32489196709.html (https://www.aliexpress.com/item/Free-Shipping-10pcs-lot-5V-Micro-USB-1A-18650-Lithium-Battery-Charging-Board-With-Protection-Charger/32489196709.html)
Its what I use between a 1w 6v solar cell  something like this
ttps://www.aliexpress.com/item/ANBES-Solar-Panel-5V-6V-12V-Mini-Solar-System-DIY-For-Battery-Cell-Phone-Chargers-Portable/32848710253.html (http://ttps://www.aliexpress.com/item/ANBES-Solar-Panel-5V-6V-12V-Mini-Solar-System-DIY-For-Battery-Cell-Phone-Chargers-Portable/32848710253.html)
and an 18650 cell on my weather station remote sender. It keeps an Arduino Nano clone alive 24/7 without any power save techniques etc.

For multiple cells, I use a bq76920 (for 3/4/5 cell setups) of up to 21 volts fully charged, but that requires a micro to run all the code, especially for charging and balancing. The code soon gets pretty hairy if you employ the correct value of paranoia  :)
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on December 27, 2018, 09:00:59 am
For single cells I've found that a USB charger like these is ideal
https://www.aliexpress.com/item/Free-Shipping-10pcs-lot-5V-Micro-USB-1A-18650-Lithium-Battery-Charging-Board-With-Protection-Charger/32489196709.html (https://www.aliexpress.com/item/Free-Shipping-10pcs-lot-5V-Micro-USB-1A-18650-Lithium-Battery-Charging-Board-With-Protection-Charger/32489196709.html)
Its what I use between a 1w 6v solar cell  something like this
ttps://www.aliexpress.com/item/ANBES-Solar-Panel-5V-6V-12V-Mini-Solar-System-DIY-For-Battery-Cell-Phone-Chargers-Portable/32848710253.html (http://ttps://www.aliexpress.com/item/ANBES-Solar-Panel-5V-6V-12V-Mini-Solar-System-DIY-For-Battery-Cell-Phone-Chargers-Portable/32848710253.html)
and an 18650 cell on my weather station remote sender. It keeps an Arduino Nano clone alive 24/7 without any power save techniques etc.

For multiple cells, I use a bq76920 (for 3/4/5 cell setups) of up to 21 volts fully charged, but that requires a micro to run all the code, especially for charging and balancing. The code soon gets pretty hairy if you employ the correct value of paranoia  :)

After posting yesterday I bounced across the internet and found better information about Lithium Ion Chargers
I think the TP4056 is a clone of the 03962A module that you linked above. These chargers have inefficient Linear regulators in them and better options are available.  Found this video comparing 4 different charger modules in a shootout . They are talking highly of the TP5000 Switchmode  single cell charger which has good charge curves and can be set to charge 2 different Lithium battery types.


A Review of the TP5000 with lots of graphs and information
https://lygte-info.dk/review/Review%20Charger%20TP5000%204.2-3.6V%20module%20UK.html
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on December 27, 2018, 03:50:54 pm
I found this little Gem after looking around some more.
It is a 2s charger with a buck converter input. Voltage is 9.4 to 20 volts, perfect for 12 volt input.
Output is 2 cells in series with all the protections and balancing needed.
https://www.ebay.com/itm/Intelligent-Balance-Charging-Protection-Board-2S-Packs-18650-lithium-Satellite/311721987212?hash=item4894140c8c:g:J~kAAOSwCGVYBRVB:rk:14:pf:0
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on December 29, 2018, 08:56:19 am
After learning some more I have discovered another issue to watch out for when Charging Lithium Ion batteries.
--- Do not attempt to Charge a Cell that is below Freezing Temperature. ---
The cells have trouble accepting the charge when they are that cold and it causes the same problems as Overcharging.
But fine to discharge in temperatures as low as -20c ... -5f.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: Pete on December 29, 2018, 02:40:23 pm
Hi Woof, thanks for the information on the Lithium cells. Many people are being lured into using Lithium batteries for their solar systems these days. From what I have seen I would not be prepared to go that way until they are proven. Seems that there are plenty of issues with correct charging that need careful attention.
I just bought a new set of Gel batteries for my solar system, my 20 year old Flooded cells finally gave up the ghost.
I did look into lithium or LIFE PO4 batteries but the cost and fickleness seemed not worth it.
To me for large systems Lead acid have proven their reliability.
Glad to see you having so much fun with LED's, they sure have come a long way in a short time.
Pete
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: rossw on December 29, 2018, 03:42:37 pm
I just bought a new set of Gel batteries for my solar system, my 20 year old Flooded cells finally gave up the ghost.
I did look into lithium or LIFE PO4 batteries but the cost and fickleness seemed not worth it.
To me for large systems Lead acid have proven their reliability.

I ditched my lead almost 5 years ago, and went LFP (LiFePO4).
Would I do it again? In a heartbeat!
They are stiffer, more efficient, smaller, lighter. They don't droop, they behave a lot like capacitors. Charging is a breeze.
I simply stopped worrying about batteries any more and the freedom is wonderful.
I can't say it's a "big" system - I've about 45kWh (900AH @ 52V) and they really are chalk and cheese.
One big difference between your site and mine, is that even in the coldest part of winter, mine never get below about 14 degrees C, due in no small part to being in an underground bunker :)
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on December 29, 2018, 04:24:32 pm
I ditched my lead almost 5 years ago, and went LFP (LiFePO4).
Would I do it again? In a heartbeat!
They are stiffer, more efficient, smaller, lighter. They don't droop, they behave a lot like capacitors. Charging is a breeze.
I simply stopped worrying about batteries any more and the freedom is wonderful.
I can't say it's a "big" system - I've about 45kWh (900AH @ 52V) and they really are chalk and cheese.
One big difference between your site and mine, is that even in the coldest part of winter, mine never get below about 14 degrees C, due in no small part to being in an underground bunker :)

+1 on everything that Ross just said

Yes, big lithium batteries are more expensive. But they are efficient and will suck up the juice and aren't stingy about giving it up either. Plus the added cost of a different charging system.

All the things that you should be worried about are mentioned in my Original post at the top. I even added the part about charging if frozen in there. The charging systems have been figured out and are cheap and easy to build yourself from off-the-shelf PC boards. A good Lithium battery will cycle 6000 times with 80% discharge. Check out this one from Battle Born. It has all the protections except Balancing, built into the battery.
https://battlebornbatteries.com/shop/12v-lifepo4-deep-cycle-battery/

Then there are these from Alibaba, cheap and need external protection boards.
https://www.alibaba.com/product-detail/Lithium-Iron-Phosphate-3-2v-40ah_50041926622.html?locphyscl=9012725&pla_localcode=&pla_country=US&pla_prdid=50041926622&src=sem_ggl&src=sem_ggl&adgrp=64560580995&cmpgn=1658657278&pla_group=293946777986&ntwrk=g&pla_lang=en&gclid=EAIaIQobChMIquuXponG3wIVlVuGCh0FngfoEAQYBCABEgIByfD_BwE&dvcmdl=&pla_adtype=pla&pla_channel=online&position=1o4&pla_mrctid=128518556&device=c&mark=google_shopping&mark=shopping&locintrst=#shopping-ads


Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: Pete on January 02, 2019, 08:55:07 pm
Hi Ross, just wondering . Did you have to change regulators? Your system is big by my standards. We use 12 volt and have 660 amp hour batteries, so 900 amp hour 52 volt is huge to me.
What batteries did you use?
I will look at Life Po4 when my current batteries die, which hopefully won't be for another 20 years. Who knows what will be the new chemistry then.
Cheers
Pete
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: rossw on January 03, 2019, 04:54:00 am
Hi Ross, just wondering . Did you have to change regulators?

I didn't have to change anything at all. I used the same inverter, charge controller, switchgear, everything.
I will admit I tweeked some of the settings to better suit the different technology.

Quote
Your system is big by my standards. We use 12 volt and have 660 amp hour batteries, so 900 amp hour 52 volt is huge to me.
What batteries did you use?

The first lot were from a company whos name I now can't remember, but who made the best prismatic 300AH cells for my application at the time. When I went back for more, they were gone and I had to find another supplier. Many more to choose from, but lots of rubbish in there too.

After all my research, I elected to use only the prismatic cells, and so far I've been completely happy with that choice.

Quote
I will look at Life Po4 when my current batteries die, which hopefully won't be for another 20 years. Who knows what will be the new chemistry then.

Yeah, I doubt it'll be LFP in 20 years!
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: solarnewbee on January 18, 2019, 02:02:15 am
Hi Ross!

Finally got my system up and running and went with 32 200ah lfp’s. Bit of a learning curve charging these things. I bought 2 off brand mppt  chargers I setup according to the book but I’m still not sure if float and refloat and absorb rate are correct.

Found out quick this 24v PJ won’t run everything in this place all at once. Pulled out the manual and it does show 3.5kw is the limit for a 8kw. I will be bringing over a 15kw next year.

I almost bought 12 volt lfp packs that had built in bms with cutoff charging relay but then found out they were populated with 18650’s. I just don’t think I can trust all those cells lasting. If one cell goes, so goes the the pack?
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: rossw on January 18, 2019, 09:31:10 pm
Finally got my system up and running and went with 32 200ah lfp’s.

They look quite similar to my second bank, although of course you've hooked 'em up differently.
I went 16S of 3P (ie, 3x200AH in parallel, in series with 3x200AH in parallel, in series with....)
I'm sure you'll be loving them.

Quote
but then found out they were populated with 18650’s. I just don’t think I can trust all those cells

Yeah, I found quite a lot like that, and it scared the willies out of me. I rejected anything that said it had "cylindrical cells", and by the time I was ready to buy, if it didn't specifically say prismatic, I crossed it off my list!

Good to see the progress!
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: solarnewbee on January 19, 2019, 10:18:00 pm
Just awoke to low batteries again. Family plugged in 2 e-bikes to charge and the system ats did its job. I noticed the data on the bms shows the first 2 blocks show 3.032v whereas the others are at 3.1v. Apparent I need to equalize them so I was wondering what you would do. 8 blocks in series for 24v 4 sets in 2 banks. The bms is only reading the first 16 blocks since I haven’t purchased additional sensors. Been so busy working on the house I haven’t even put a meter on them. I’m going to keep the inverter off for 24 hours and see if they reach float and check each cell.

Ok now for the dumb question. “Never disconnect under load”. Should the battery always disconnect first before hitting the pv breaker? Silly questions but after reading threads here and many places some things are just not covered. 

I was building the battery bank and needed longer bolts for the cable connectors. Every hardware store had standard thread in a country that uses metric. One exception, Ace Hardware! 2 drive, only in the Philippines 🇵🇭.

William
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: lighthunter on January 20, 2019, 06:52:17 am
So, you have four series strings 8 cells each? Then you paralleled the 4 strings?
Some ppl go off when they see someone using an LFP without BMS on every cell  :)
The real world always brings challenges and necessities. I understand completely.
Your existing BMS has done a good job so far and the variance of .068 is not a problem
since you are stopping discharge at 3v. I personally wouldnt touch them with anything
but a meter for now as long as they are all that close to each other. Others may disagree but
always maintain bottom balance (never never top balance) especially if some cells are unmonitored.
Through their life there will be differences in cell capacity and you wont loose a cell if the voltage goes a little high on one but if voltage goes low on one during discharge the stronger cells will run over it and kill it. (that assumes no bms monitor of course). Be careful of factory BMS monitors that leak power from cells unequally and cause unbalance. One such device is the (cellog8S). It works great, graphical display and recording etc, but leave it
connected for a week and expect unbalance. They use the first two cells to power the device. It isnt worthless however, very useful with a connector to temporarily monitor, record details. With your investment you probably want a better BMS with auto balancing. Choose carefully when deciding on BMS equipment though, often times BMS curcuits are less reliable than LFP cells and a bms failure in worst case can ruin a cell. Fun stuff!  :)

Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: solarnewbee on January 20, 2019, 10:47:25 am
Thanks LH for the info, puts me at ease. The bms sensors are powered at each battery and then plugged into a bus that runs to a control module. The control module is powered by a 24v din rail ps. Still waiting on the English software so I’m depending on the CM screen data. There isn’t any balancing done as far as I know but communication with the Chinese company is sporadic.  I do get cell volts impedance and temperature. Current sensor on each bank show charge and discharge which seems useful. I have ordered 16 more cell sensors today to cover the other cells so I will have that covered before I head back to the states.

Can you explain what bottom balance means? I read somewhere that I should have bolted all of them together in parallel negatives to negatives positives to positives for a few hours and that would equalize them, any truth to that?  I put a meter to them when I got em and they all fairly close.



Thanks
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: lighthunter on January 20, 2019, 06:03:41 pm
Once you get the other cell monitors in place, this info becomes lots less important.
The discharge curve of an LFP cell has a pretty steep voltage drop around 2.8v indicating an empty cell. (dont change your 3v minimum bms setting unless all cells are monitored).

Bottom balancing refers to equalizing all cells to reach this (empty drop off ) at the same time.
Your cells are new and likely to have very similar capacities, therefore the upper voltage knee for full charge will occur at the same time for each cell as well as the lower knee will happen at the same time for all cells when they are balanced.  But lets assume they are getting along in years and capacities vary by 5-10AH. This would mean you could align the discharge knees of all cells to reach empty at the same time and when you charged them one with lower capacitiy would reach full and climb past 4.0v while the others are still reading high 3.3s. If you want an LFP to last avoid going below 3.0v or above 3.5v theres really not much capacity to gain on either end. Ross likely can improve on these numbers.

The bottom balancing trick comes from the EV guys who became frustrated with the poor reliability of the early BMS systems and in some cases decided they were better off without. (kind of like an oil pressure guage that leaks and causes your engine to run out of oil). If you get rid of the BMS the best way to protect your LFP cells is to meticulously align every cell at the lower knee on discharge and monitor the pack voltage for your fuel guage. EV fellas are trying to get the best range possible sometimes at the expense of the cell. Your application can be more conservative with the min and max points and treat the cell better.

Regarding bolting the cells together, Nope, i would not do for balancing. The current exchange without resistance could be damaging. If you want a simple way to balance manually then choose a low voltage 6v halogen lamp of 100w or whatever is handy. Then you can connect neg to neg and positives together through the lamp. Use something available and cheap, any low resistance filament or resistor will do.  Once two cells have equalized with low resistance then you can bolt together if building a pack etc.

Those prismatic cells though expensive are the closest thing ive ever seen to an ideal (textbook) battery. For all practical purposes of realistic calculations you can even skip the symbolic internal resistance. Do try to cover/insulate those terminals and fuse where strings join. Lead acids can source huge current but LFP  can produce current beyond anything you can imagine. Unless there is protection there may not be a tomorrow. Cant say ive seen one shorted but ive seen 4kw from a pack the size of 2 car batteries without much v sag.
Unless external equipment unbalances your cells, they dont need much balancing but monitoring is a necessity.

Good to see the progress, i feel your pain with the variable unexpected loads throughout day and night  :) imagine trying to manage the Grid. :(
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: rossw on January 20, 2019, 06:58:28 pm
Ross likely can improve on these numbers.

I have my generator set to autostart if a cell gets to 3.125V (at light load) or 3.0V (at full load).
Overvoltage alarm (which has only gone off a couple of times, due to freakish high wind when batteries were already full, or due to a setting error on one of my low current chargers) - at 3.50V/cell.

Quote
Your application can be more conservative with the min and max points and treat the cell better.

Agreed.

Quote
Those prismatic cells though expensive are the closest thing ive ever seen to an ideal (textbook) battery. For all practical purposes of realistic calculations you can even skip the symbolic internal resistance.

I love 'em :)

Quote
Lead acids can source huge current but LFP  can produce current beyond anything you can imagine. Unless there is protection there may not be a tomorrow.

I had a friend bring up his son to look at my system yesterday. He's an apprentice sparkie and interested in PV, batteries etc. Was fascinated by the "reality" rather than the BS he's being sprouted at work by knuckle-dragging know-nothings that may have all the book learning and papers but don't actually know how stuff really works.

Like he was surprised my battery packs were both "down-around-and back". They "always do them in one long run".
When I pointed out how short my cables were to the inverter it was like a light bulb came on.

He questioned my fuse at the MIDPOINT of my battery bank. (Ie, between cells 8 and 9, or at the 24V interconnect).
They only ever use a breaker on the +V connection. When I pointed out all the places along a battery bank (that went down and back) were you could conceivably have a short circuit and that with their arrangement NONE of them would have ANY protection - whereas with mine, virtually every likely scenario was covered.

Fusing with high rupture capacity fuses is a small expense compared to the safety they offer.

Quote
Unless external equipment unbalances your cells, they dont need much balancing but monitoring is a necessity.

I sleep well at night with the monitoring. Just KNOWING everything is as it should be has a value beyond money.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: solarnewbee on January 22, 2019, 08:28:49 am
I have a plastic cover constructed that goes over the all the batteries  heat shrink tubing goes on this weekend and the daughter has come up with some laminated dielectric  rubber that will fit over the bolt heads. Each bank has 125a 10kva dc breakers. Since I only needed 8 for 24 and little space I had to run them in 1 line instead of down and back and then the next pack turned 180 to keep the positive short for all packs. Wondering if I should more breakers and where. I’ll post a drawing of what I have and I’ll certainly heed your advice on that subject. Cells are topping out all consistent at 3.33v at sun fade and 2.89v come morning.

I am installing a automatic starting 3000w dc inverter lp generator Friday. Just bought 10 meters of 30mm2 welding cable to connect it. This thing uses the batteries to start itself when the batteries voltage drops below 24v and shuts off when levels rise above 26v. At least that’s what the brochure claims ha! Next year we move and the windmill goes up, dual 3 phase 3000w  so that equates to an average of what, 800w? Except typhoon season of course.

As always thanks for the expert advice.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on February 20, 2019, 06:16:01 pm
I've been educating myself on the difference between Lithium Ion and Lead Acid batteries.
The way I am understanding it is that you can replace Lead Acid batteries with Lithium Ion batteries in a 4:1 Ratio.
If you have 100 amphours of Lead Acid batteries, you will want to replace them with 25 amphours of Lithium Ion batteries.
This is because you get a 50% gain in charging efficiency, using less power in the charging and recovery of energy from the batteries.
Then you get another 50% because you can safely use 100% of the battery charge, where using Lead Acid batteries it is recommended to only discharge the batteries to 50% to increase their life.

I have been totally considering making a Lithium Ion Bank that is five 4.2v in series making a max charge of 21 volts. Then using a big Buck Converter to get back down to 12.6 volts for the loads.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: rossw on February 20, 2019, 07:34:56 pm
you can safely use 100% of the battery charge
.....
making a Lithium Ion Bank that is five 4.2v in series

This is FAR from "safe".
There WILL be differences between cells. In an unprotected, series pack like that, you WILL have one cell that gets to 0% charge before the others. Continuing to discharge the pack to what you think is 100% will LIKELY reverse bias that cell.
When then charging the pack, one cell WILL get to 100% capacity before the others.

Your best outcome is a destroyed cell. Your worst outcome is fire and/or explosion.

When playing with these cells, make sure you operate with a DECENT safety margin, and/or with suitable protection (electrical, thermal, physical containment or a combination thereof).
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on February 21, 2019, 07:05:03 am
Oh Yes
A battery management system was implied.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: solarnewbee on March 17, 2019, 09:06:53 am
Hey woof,

Are you building your own 4.2v lith ion batts from 18650’s? If so are you welding them together in parallel or in holders?  I saw a guy on YouTube that builds power walls with them and has boards with holders that have bms that plugs into board. Each cell is monitored constantly. No idea where he found that stuff but it intrigued me. Search jehugarcia and you might find something useful. I just went and watched and looks like the boards are a diy kit that he sells. The other video I saw he was using a digital bms instead of a hit or miss mosfet only based bms that fails short pass thru.

I like the prismatic lifepo4 3.2v myself but the initial cost can leave a burn. I got 800ah and I wonder as Oz once said that it sounds nice to have a large bank of ah but can you fill it. Batteries with fuel gages built in someday?

I was wondering about what you said about less ah with lithium but if your total kWh usage stays the same the battery bank will get a lower voltage level sooner and the inverter shut down? Well, whatever the results as long as your still having fun!

Adios Muchacho
Title: What will Replace Lithium batteries
Post by: WooferHound on March 20, 2019, 11:57:36 am
What will make Lithium Batteries Obsolete ?

Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on March 21, 2019, 07:25:53 am
Hey woof,

Are you building your own 4.2v lith ion batts from 18650’s? If so are you welding them together in parallel or in holders?  I saw a guy on YouTube that builds power walls with them and has boards with holders that have bms that plugs into board. Each cell is monitored constantly.

I was wondering about what you said about less ah with lithium but if your total kWh usage stays the same the battery bank will get a lower voltage level sooner and the inverter shut down? Well, whatever the results as long as your still having fun!

Adios Muchacho

The 20ah lead acid battery on my small hobby 12v Solar Power has finally stopped being productive so a new project is materializing.

A friend of mine that lives down the street has moved to another city and left me a bunch of Old Laptops that I have recovered the batteries from them. Ended up with forty 18650 batteries. Charging and Testing them right now, and if they all work, I plan to make a 21v 20ah battery bank with them, easy expansion later. It will start out as 5s 8p. Eight batteries parallel, then Five groups in series.

I've seen many Battery Holder styles on YouTube and eBay and have decided to use sockets and not solder the batteries.
My solar panels are 23 volts (open) and I might not need a charge controller so much with this 21 volt bank.
Battery Bank voltage will be between 14v and 21 volts using the Battery management board I'm looking at.
A buck converter will be used to bring that voltage down to 12.6 for distribution and usage.

Here are the planned parts to be ordered soon, some of it from China . . .

Battery holders, groups of 4
https://www.ebay.com/itm/5Pcs-Li-ion-DIY-Battery-Plastic-Case-Holder-for-4x3-7V-18650-Battery-M6M1/252732634852

5s Charging Balancing board 20a
https://www.ebay.com/itm/5S-20A-w-Balance-Li-ion-Lithium-18650-Battery-Charger-BMS-Protection-PCB-Board/264077586312

Buck Converter 15a
https://www.ebay.com/itm/200W-15A-DC-DC-8-60V-TO-1-36V-Synchronous-Buck-Converter-Step-down-Module/112985055478

Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on March 22, 2019, 09:19:32 am
Ordered the parts this morning
all from China
Now to wait about a month for it all to get here
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: solarnewbee on March 22, 2019, 11:12:06 am
Interesting, look forward to your progress. Minus the boom of course. Have fun with it!

😊
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on April 19, 2019, 03:54:21 pm
Today I made the standard DIY 18650 Lithium charger that you can find 100 times on YouTube.
It's four TP 4056 charger modules hooked up to 4 Battery Holders and powered with a 3 amp 5 volt wall-wart transformer.

[attach=1]

This is just a prototype. The module on the right-hand side does not work. Ordered 15 more of these.
Was needing something that would reliably charge the cells to a known voltage for testing and assembly into some 5s 8p battery banks.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on May 12, 2019, 05:50:50 pm
My first Lithium 18650 charger did 2 batteries and was just a 3 volt transformer rectified and going directly to the batteries. Max voltage on that would be just over 4.1
(https://www.anotherpower.com/board/index.php?action=dlattach;topic=1340.0;attach=7954;image)


Yesterday I took the breadboard charger shown in the Last Post and mounted it permanently into that same box.
[attach=1]


The charger modules were mounted behind holes drilled in the box so the indicator lights would show through.
[attach=2]


Accidentally put a Cell in Reversed polarity and killed the module, replaced it this morning with the promise that I won't do that again.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on May 12, 2019, 08:31:26 pm
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on June 04, 2019, 08:11:41 am
Ordered the parts this morning
all from China
Now to wait about a month for it all to get here

The discussion and Construction of this Lithium 18650 Power Bank is continued here . . .

https://www.anotherpower.com/board/index.php?topic=1331.msg14896#msg14896
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on June 24, 2019, 02:43:21 pm
Solar Lithium Batteries ARE CHEAPER than Lead Acid! And Better in Every way. Proof Included
Once you go Lithium you Never Go Back

Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: solarnewbee on July 04, 2019, 07:08:08 am
Hi Woof!

I love my LifPO4 3.2v batteries, a bit expensive at the numbers I purchased but for the amp hours I get and the charge cycles of up to 5000 or more per recent data I'm ecstatic! Life really is better and cheaper with lithium.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on July 05, 2019, 12:36:20 am
One of my favorite things to do when I had Lead Acid batteries was to watch how much the voltage sagged when I powered stuff on.
 but now
With Lithium  batteries, it hardly sags at all.
Title: Re: Charging and Using Lithium Ion 18650 Batteries
Post by: WooferHound on February 09, 2021, 09:47:58 am
Haven't posted in a while but I'm still going Full Throttle into total use of Lithium Ion 18650 batteries.

[attach=1]

I had built a Battery Bank for my solar power that was capable of holding 80 Lithium 18650 batteries, but I was filling it up with Used Salvaged Laptop batteries of unknown age. The only test made on those batteries was a Charge and then a Voltage test after a week of sitting unused.
Was having lots of problems with cell balancing with the used cells and replaced 50 used cells with New, well rated cells, plus filled the bank to capacity with 80 cells.
This Bank is 16 Parallel & 5 in Series. it is an 18 volt bank that can swing 15 to 21 volts.

[attach=2]

Purchased 2 Cell Capacity checkers on eBay. Then Charged and checked the amphour capacity of all the Used cells from the old battery bank. In that process I found 2 or 3 Heaters that overheat when charging. Threw away about 5 batteries that were rated less than 2000 ma.

[attach=3]

Now I've got about 40 used 18650 batteries that are tested up to a reasonable capacity for use in plenty of smaller rechargeable projects. And my solar power now has a small 1.1 KWh battery capacity.

Enough to have some serious Fun with . . .