Harvesting and Testing Batteries

Hopefully I can keep track here, all the 18650s I'm able to save from the recyclers.
I've got lots of ideas for using these. My first attempt will be a starter battery for my lawn mower. I also want to make a couple batteries for an e-bike I will be building later.

So I got a few batteries from around town. Two out of 3 computer shops were happy to get rid of their old batteries. The third flat out refused. I also had some luck with the local e-waste company. There's actually two in town, but only one was helpful. So I at least have 3 sources of batteries so long as they actually have any on hand when I show up.

I got my first batch cleaned up and sorted by voltage:




My iMax charger came in the mail a couple days earlier and I started playing around with settings and battery chemistries. Seems the iMax is rather picky about the voltage of the cell you want it to charge. Most of my cells are too low for the charger to recognise. So I set about trying to figure out how to charge them without the charger.

Here's a video showing how I started. Keep in mind though that I'm an electronics newb, and am probably doing everything wrong. LOL

If you start charging them on the NIMH setting, the imax should bump them to a voltage you can use on the li ion setting, I think it's LIPO setting

The 3.3V rail of a computer power supply can also give them the boost they need to be able to be charged in the imax as well.

Korishan said:

The 3.3V rail of a computer power supply can also give them the boost they need to be able to be charged in the imax as well.

Click to expand...

Yep, thats the method I use. I have a charging rack I made that holds 18 cells in parallel powered by the 3.3V output of the computer power supply. Its the bullpen for the opus.

Caution...If the cell is shorted internally, it will heat up. my power supply can push 20 amps at 3.3 Volts. So don't walk away before knowing if the cell starts heating. I have not experienced any smoke or burning, but I am worried about it. I need to put some fusing into the setup and get some cheap easily changeable fuses. But for now, Its my fingers testing for heat.

I wish I had a much smarter automated tester, charger, discharger that would would charge from 0 volts. Maybe the TP4056 modules will charge from 0 volts. I will soon test those out. That would be a lot safer for "walk away check later" charging.

if it is safetyyou are going for, get yourself some of these 1 or 4 pack cellholders and put them in parrallel, load 2/3 of them with tested, charged ones, not really important to use high capacity ones and then add the "dead" ones to the mix in the separated compartments
now the worst that could happen is killing the good ones by pulling them to 0v

If you live near a vehicle salvage yard, you can go in and pull loads of fuses from the cars. You can usually walk out with 20 or so without them saying much. You could get both blade and tube (glass) style fuses
Also a good source for 18awg wire.
Our local one here has free admission day. One day a week, they don't charge for going into the yard.

And, there are several eBay sellers that sell cheap blade fuses. I wouldn't necessarily use them in full production, but they could be used in this type of application. Those blades go down to 3A I think. For recovery purposes, I think having a fuse at a low blow point would be good, even if the fuse blows under normal conditions after repeated chargings (due to gentle heating during charging)

Thanks all! Good ideas.
I've changed some things and I'm getting some better results. Still playing around, but here's a video of my latest attempt:


Also, thanks Admins for helping me embed my videos properly.

I guess I forgot to publish my last post. It wasn't much anyway, just a short update making improvements on my DIY cell charger:

Finally making some progress testing the cells I've harvested:
Man, I rambled on for about 45 minutes in the original recording. Lucky for you guys, I managed to edit it down to just 10 minutes or so.

You guys are making this more complicated that it needs to be

Just get a cell holder that takes more than one cell in parallel. I use 8 in parallel. You can stick in 7 low cells and 1 regular cell. The regular cell will be enough to trick the dumb voltage checker into starting and will charge them just fine. There's no reason to use multiple chargers, bump charge. 3.3v rails, etc. It would be nice if there was a way to disable that voltage checker on the iMax since it's kindof useless.

Today I received two more OPUS and started the new testing, no more of this discharge/refresh crap. I have a question though, has anyone found good RED's? I just got 5 of them at 2700ma +! I thought they were all burners?

RobertBaumer said:

Today I received two more OPUS and started the new testing, no more of this discharge/refresh crap. I have a question though, has anyone found good RED's? I just got 5 of them at 2700ma +! I thought they were all burners?

Click to expand...

Yes, I get a ton of them now - several hundred tested around 2500. 95% of them have a light blue ring. I don't get burners ever now that I'm using new old-stock batteries. I still haven't been able to figure out what causes them to go thermal like that.

are we talking red sanyos here? i had them in hp packs, with purple isolator, around the 1900-2000mAh

I have a bunch. all about 1800. Some of mine are not Sanyo's though. It's all in the model

I like to precharge to 3.3 volts, it lets me weed out the open circuit and burners when I can check for heating or non charging ahead of putting them on the opus for charging. That may change when I move to the tp4056 charging process.

Honestly, it's all I can do to open enough batteries to process 100 cells a day right now.

"You guys are making this more complicated that it needs to be..."

My quote button isn't working. Anyway, my DIY charger is as much for fun as it is for processing batteries. And every time I solve an issue with it, I learn a little bit too. I think my issue with the volt meter is that its not getting enough volts or amps (or both?) to give an accurate reading. I went back and read the specs, and they say it needs at least 2.5V to function properly. I might replace it with a meter that accepts a power source separate from the one being tested. Again, just for fun.

So I've been charging and discharging on both the iMax and the Opus. I don't like the way the Opus charges. Maybe there's something wrong with mine? It often calls a battery full when its only at 4.15V or so. Also, it doesn't do storage charging. On the other hand, I like the way the Opus discharges better than the iMax. Especially as it can do 4 cells individually and the iMax can only do 1 at a time. If you want to find the charge capacity of an individual cell. I think the two chargers compliment each other very well.

As far as read coated cells, I think most of the ones I've found are Sanyo. I've only tested 10 of them, but they've all done well so far. I've only had one cell so far that's too hot to handle, and that was a Panasonic. I don't have a good way to measure temperature yet though.

So far, I've got 56 cells that charge and have at least 1000mAh. They're sitting now waiting for the voltage drop test. Seems most people wait 1-3 weeks before testing?

Yes, 1-3 weeks is a good waiting period. I actually have gone longer than that as I've had some sitting 2-3 months

i have my first 40cell 1900mAh pack sitting on my desk for sporadic testing purposes, at least thats what i tell my wife...., so far i have identified 2 cells that get lower than the rest, i think they lie there for 2months now, we could calculate it from the depth of the dust buildup^^

I finally got a switch I like for my charger.




Also, I found 8 of these Moli cells made in Canada. I looked around, and it seems they don't make them anymore. I've processed 4 so far, and they've performed very well. About 1900mAh.Theyall started at 0.5V-0.7V, and the 4 I've done are sitting at 3.78V after being charged to 3.79v for storage. Better than some of the 2+V cells I've tested so far.

First batch of cells are finally done testing! I've got31 cells ranging from 1044mAh -2284mAh. All of them had a voltage drop of 0.04V or less.



I'm still trying to decide just how to group them. I'll be saving my best cells for an e-bike, and some of the less good cells for a starter battery.
I think the starter motor draws around 20A. Not sure though, my 10A multimeter blew its fuse at around 18A, and my 300A meter barely twitched. Once I know how many Amps the starter needs, I'll be able to tell how many cells I need.

I've also decided to try out some of those TP4056 boards that are all over You Tube. I've been hesitant because they all do 1A charging, which I think is too much for my cells. But I've discovered if you change out one of the resistors, you can reduce the top current. So I looked over some old circuit boards I have and came up with these little guys:



These were a lot easier to de-solder than I though they would be. I think the hardest part will be not loosing them.
Also gave me an excuse to play with the super macro on my camera.




The thing that interests me most about these TP4056 things is that they're super cheap, and also they have a pre-charge phase of something like 0.1A until the cell gets up to a proper voltage for charging. I don't think the Opus does that, and I know the iMax B6 doesn't. Testing would definitely speed up if I had cells ready to go whenever the Opus was free for discharging. So I bought 10 of these little boards. I'll modify 2 of them and use the rest for maybe 2 cells in parallel.

I've been having very good luck recovering cells less than 0.5V with my little DIY charger setup. I keep it at less than 0.1A until it gets to 3V or so, and then charge it to 3.8V and leave it there until the amps drop to near zero. I've got some cells that way which have really good capacity and charge up to 4.2V. Have to wait for the voltage drop test before I'll know if they're usable or not though. All the cells at 0V so far have stayed that way despite my best efforts. Fortunately, there's not too many of those in my pile.

Yes, the TP chargers are really nice and cheap!

Before you go and pull the resistors off the TP's, check them first to see if they are indeed charging at the 1A range. Some of the TP's are made with "spare" resistors and not all will charge at 1A. Just something to be wary of.
The 1A rating is the Max the actual TP4046 chip can handle.
Something else you could do is put a POT on the board so you can vary the amperage they charge at.

Great results! May you have continued success