acceptable voltage range for samsung lithium cells

[dougcullen]

Hello,

Just bought some new samsung ICR 26F cells from Ali Express. What is the acceptable voltage range for new cells? My multimeter is showing some at 2.90 and a few at 3.90 ! Can I just charge the weaker ones separately up to within the proper range before welding them together ? I'm thinking that the ones betw 3.6 and 3.9 are ready to connect together...

Thanks

 

[Hillhater]

No, those are huge voltage differences...why ?
You need to test for duds, and match cells of similar capacity , IR, etc before you waste time assembling them.
Search and read DrkAngels threads on 18650 testing.

 

[redilast]

I have some Samsung 26FM's on hand and measured a few all are 3.64v. I've never had cells from the same production batch that vary by more than about 1/100th of a volt from cell to cell. (e.g. 3.63 and 3.64). The wide range of voltages on the cells you get suggests foul play and that they are not new grade A cells.

So now you have several possibilities:

1) Counterfeit cells
2) Used cells
3) Reject cells
4) Bad batch? Very unlikely.

Can you try to take some clear pictures of the cells, and also maybe try to remove the wrapper on one of the cells and take pictures of that as well. Any spot weld marks on the tops or bottom of the cell cans?

 

[dougcullen]

View attachment 2

Hi Redilast,

These are all labeled 26F not 26FM

I have 54 of these altogether, but 8 of them are from a second source.
The pictures are of one of the two duds that I received that I tested at below 3.0 v (they're about 2.6 - 2.7)

Most of the rest of the batteries seem "ok" but again there's a wide range. Most of them are between 3.64 and 3.84, 4 of them are in the 3.5 range, and 4 of them are above 3.9.

Can I simply charge the ones that are a little low into the correct range, and bleed the high ones down to meet the rest ? This is my first attempt at a battery build.

Eagerly awaiting your advice !

Thanks

 

[Hillhater]

Doug,
Take some time out first, and read this thread..all of it !..
https://endless-sphere.com/forums/viewtopic.php?f=14&t=26383&hilit=Laptop+cells+pack+build
It will tell you how to test and select cells and a guide to building your first pack.

 

[redilast]

Honestly on the - end there looks like too much heatshrink. I've seen fake samsungs before, and they used slightly too much heatshrink as well. In fact you can actually buy Samsung 26F heatshrink wrappers in the Chinese market and put them on any cell you want. I suspect they might be fake. Carefully compare the physical characteristics (the look, weight, and inspect the + end carefully to make sure its the same design and shape of the others).

Also on the steel can itself on the 26F there should be some printed letters on there. Probably a production batch code number and or production date code. Do you see any printing? Another possible indication is the white ring near the + side. Does that ring just fall off or is it stuck in place with adhesive?

http://i.imgur.com/vk6xm34.jpg

http://i.imgur.com/5krt0sf.jpg

I'll also mention that regular Samsung 26F's are very rare these days. I don't know if they still make them. My suppliers don't offer them anymore, they only offer Samsung 26FM and 26JM.

If you are building a battery you should definitely also have some of the proper tools such as a hobby charger. If you have one try to do a cycle test on that cell. Then also try to do a load test and compare them with your other good cells. You can fully charge it up for example, put it under a known load of say 3A and after 10 seconds measure the voltage @ the cell, and compare that to some of the other cells.

 

[dougcullen]

Thank you Hillhater I've been reading through the DrkAngel posts, tons of great info.

Redilast can you give me an example of attaching a 3A load to test an individual cell ? Using something like a small light bulb ? How would you attach that to the cell ?

Thanks

 

[redilast]

Thank you Hillhater I've been reading through the DrkAngel posts, tons of great info.

Redilast can you give me an example of attaching a 3A load to test an individual cell ? Using something like a small light bulb ? How would you attach that to the cell ?

Thanks

I'd be interested first in your response to my above questions about if there is any printing on the steel cell can itself? And if the white ring on the + end of the cell was held on with adhesive or if it was loose? A light bulb load wouldn't be very accurate because it wouldn't be a constant current load. Honestly if you are building battery packs and stuff you should at the very least invest in a cheap half way decent hobby charger. They can be had for as little as $20. Then you can measure the capacity reasonably accurately.

 

[dougcullen]

Redilast,

Looking closely at the bare steel can, there is no text or manufacturer's stamp at all - completely blank !

I don't see any adhesive on the white ring and it is not loose, firmly attached.

Yes I'm going to get a cheap charger to try and bring the cells up to 4.2v ... maybe one that can charge 2-4 cells at once

How do i do the 3A load test ?

Unclear whether or not i was scammed here, however all but two of my 54 cells are above 3.0v so I'm going to try and work with them.

Thank you !

 

[redilast]

Redilast,

Looking closely at the bare steel can, there is no text or manufacturer's stamp at all - completely blank !

I don't see any adhesive on the white ring and it is not loose, firmly attached.

Yes I'm going to get a cheap charger to try and bring the cells up to 4.2v ... maybe one that can charge 2-4 cells at once

How do i do the 3A load test ?

Unclear whether or not i was scammed here, however all but two of my 54 cells are above 3.0v so I'm going to try and work with them.

Thank you !

They sound fake then. Never seen Samsung use adhesive to hold on the ring. Usually 3rd party companies use adhesive on the ring because it makes heatshrinking them easier. If you try to heatshrink it with the ring loose its quite easy to have the ring blow off due to the heatguns fan. Also there should be printing on that steel can for sure.

I wouldn't rush it and integrate counterfeit cells with real ones in the same pack. Sounds like a disaster waiting to happen. Contact the seller, give them the reasons you think its counterfeit and see what they say. And then probably try to source some legit cells.

To do a load test you'd need to buy a hobby charger.

 

[dougcullen]

Thanks Redilast, I just opened a dispute with the seller...

Would you recommend a reputable seller of authentic cells?

And a link to a hobby charger you'd recommend ?

 

[dougcullen]

I just dug a little deeper and discovered that I have 6 authentic cells with branded canisters that I ordered from a different vendor in california. These cells are all within .01v of eachother, and the white ring comes off the cell easily - no adhesive ! Redilast I really appreciate you helping me get to the bottom of this. Scammers ! I hope I can recover some of that $.

 

[redilast]

Thanks Redilast, I just opened a dispute with the seller...

Would you recommend a reputable seller of authentic cells?

And a link to a hobby charger you'd recommend ?

I'm glad you were able to confirm that. As for sources, I'm not sure. I sell 26FM's but you probably want 26F's if you can find them (not sure of the differences) although I hear the FM is made in Malaysia. F could be made in Korea I'm not sure. I guess you could try to find a seller on ebay that has them and just have them confirm that they are legit and then knowing what you know now, look them over carefully when you get them.

As for a hobby charger, I use an iCharger. Don't recall the model off hand but its one that can do up to 8S LiPo. But there are other half way decent cheaper options in the $20-30 range or something. Check out Amazon and pay attention to the customer reviews. Half of the hobby chargers out there use basically the same menu system and maybe the same firmware. But a hobby charger is a must have I think for anyone that is going to build a battery pack. It will allow you to test the cells capacity. The downside is most hobby chargers are only good for 6s or 8s Li-ion/LiPo cells. And most eBike packs are much more than that so you won't be able to charge the whole pack.

 

[flippy]

these cells are fake. i have seem them before.

 

[999zip999]

Where you live ? How did you pay ?

 

[dougcullen]

I'm in New York and I bought these over Ali Express. I opened a dispute with the seller who claims they're the real deal and says regarding the highly varied voltages: "battery life may be different, this is normal, do you not know ? "

!!!

 

[flippy]

congrats, you got shafed.

next time buy from a reputable retailer.