Author Topic: Charging and Using Lithium Ion 18650 Batteries  (Read 7353 times)

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Offline WooferHound

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Charging and Using Lithium Ion 18650 Batteries
« 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.



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.



There is solar lighting on my bicycle and there is an 18650 battery in the back of the solar panel there.



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
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Offline ClockmanFrance

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #1 on: December 26, 2018, 01:20:19 pm »
Nicely written post 'WooferHound'.

I love real empirical evidence.

Offline frackers

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #2 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
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
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  :)
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Offline WooferHound

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #3 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
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
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
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Offline WooferHound

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #4 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
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Offline WooferHound

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #5 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.
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Offline Pete

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #6 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

Offline rossw

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #7 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 :)

Offline WooferHound

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #8 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


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Offline Pete

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #9 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

Offline rossw

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #10 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!

Offline solarnewbee

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #11 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?
SN

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Offline rossw

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #12 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!

Offline solarnewbee

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #13 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
SN

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Offline lighthunter

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Re: Charging and Using Lithium Ion 18650 Batteries
« Reply #14 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!  :)

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