how to check if these 18650 are good and capacity ?

[herbeapuce]

Hi. My knowledge of battery function and technology is pretty weak....

I was given 88 used 18650 and I would like to check their capacity, if they are still good, the better ones... etc..
they came off laptops and power tools...

I have an "intelligent'" charger (Powerfocus BT-C3100) with many options and a good tester ( that I don't know most of the features...)

how can I check that please ? what is important to know here ?
thanks for your help.
Stef.

 

[fmc1]

It looks like you have all the tools you need. I have recovered lots of batteries. My recommendation is to check the voltage on each one with the DMM. Any of them with less than 2.5V I would discard because they are damaged and not worth the effort to recover. Also any that are visually damaged like dents throw away, torn wrappers can be repaired but don't use them until you do so. The ones that are left charge at 500mA while periodically checking them for getting excessively hot or if you see them stall at a certain voltage, if that happens also discard those. The rest I would put through a test cycle. That will show you the discharge capacity.


There are a few batteries that I recognize from your photo.

The Samsung 26A is rated at 2600mAh with max discharge 20A

The Samsung 20R is rated at 2000mAh with max discharge 22A

Both are good high current batteries but not a lot of capacity.

The Samsung 28A is rated at 2800mAh but its maximum charge voltage is 4.30V not 4.20V like 95% or more of 18650's ever made. Your charger can handle 4.35V batteries if you open it up and change the switch on the PCB to 3.8V. Just remember to set it back to 3.7V when charging all other LiIon batteries. Of course you can just leave the switch alone and charge them to 4.2V but you will not get the maximum capacity.


I can't tell based on the markings what all the green ones are. A few manufactures have used green wrappers over the years however to me that color looks very Sony green. The only one that I can read is SF US18650VT and there is such a battery but wow is it old. They were 1100mAh with a 10A max discharge. But remember they were some of the first 18650's ever made that could handle 10A if not the first. Today you can buy a Sanyo NCR18650GA rated at 3500mAh and 10A max discharge for about 6 dollars, maybe a little less.


I hope this helps


Frank

 

[Prepped]

When you insert your batteries into your charger, you can hit the 'mode' button until 'Charge test' appears. It will fully charge the batteries, discharge them, and then fully charge them again and display their mAh rating. Could take a while.

 

[herbeapuce]

thank you very much for your help. it's appreciated. Very knowledgeable people here !
unfortunately my charger died on me today. right after loading some more batteries, something burned inside the charger. the fans stopped and a very nasty smell filled the room.... ho well
now I need to buy a new charger....

About if I hijack my own thread and ask you what charger should I get now ? I need to charge 18650 and the rechargeable AA and AAA... something cheap but hopefully more durable than that one... Any recommendation.
I was charging the batteries at 10 mA ( <-- edited, at first I wrote 10A...) ... was that too much ? I guess so...
thanks again for your help.
stef

 

[WalkIntoTheLight]

I was charging the batteries at 10 Amp... was that too much ? I guess so...

10 amp charging??? Yeah, that's definitely way too high. Are you sure it was that fast? Most of those cells should probably be charged at around 1 amp.

Given the internal resistance, I suspect your charger almost immediately went into CV mode at 4.2v and dropped the charge rate for the vast majority of the charge. Still too hard on the cells, though. Although unlikely, you may have even damaged the cells internally. Be careful with them.

 

[herbeapuce]

10 amp charging??? Yeah, that's definitely way too high. Are you sure it was that fast? Most of those cells should probably be charged at around 1 amp.

you are right. I checked and it was 10mA. sorry . (I will edit my post)

 

[WalkIntoTheLight]

you are right. I checked and it was 10mA. sorry . (I will edit my post)

Okay, well 10mA sounds waaaay too slow, now. It might be okay for trying to revive a cell that reads 0v, but only for a few minutes. Then, you'd go with 500mA or 1000mA. A 10mA charge would take about 10 days to charge one of your cells. I don't think you're that patient, are you?

 

[ChrisGarrett]

Get a note pad and black Sharpie marker and itemize them so you can keep track of what's doing what.

Start in batches of similar make/model and see where they'll charge up to and write it down with the date. Set aside and charge at something like a benign 500mA, outside, if you can.

After two weeks, check their voltages and discard any that have crashed more than a few clicks. For those that are stable, you can charge them back and then do discharge tests to get an idea about their capacity.

Chris

 

[herbeapuce]

Okay, well 10mA sounds waaaay too slow, now. It might be okay for trying to revive a cell that reads 0v, but only for a few minutes. Then, you'd go with 500mA or 1000mA. A 10mA charge would take about 10 days to charge one of your cells. I don't think you're that patient, are you?

my brain must have fried with the charger .... Sorry but the right number is 1000mA, so 1A.. My charger , before it died , was charging the cells at 1 A ( or 1000mA, as I can read it on the screen...) Sorry again for the confusion. me bad....
once again thank you all for your answers.
I did a bit more reading here and found out about that huge battery charger review page here.... I will look at my options, but meanwhile feel free to tell me some recommendations if you want.
stef

 

[herbeapuce]

Hi.
I ended up buying a Zanflare C4 smart charge... after reading the reviews.
thank you
stef [h=1][/h]