BLF Community Battery Pulls Overview Thread (Laptop packs and Tool Packs)

thank you, i will get the OP updated asap

I think I may have done this, one of these measured 0 amps.
I usually peel the strips off with needlenose pliers, like opening a sardine can.
Next time I’ll be more delicate.

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I can’t say whether or not that is likely to damage the cells, but after taking more care in tearing apart more packs, I’m certain that, at least in the Dell packs with LG and Samsung cells assembled in China by SMP, there is some other reason for the dead cells, because I’ve had multiple such packs with dead cells in parallel with non-dead cells where I’ve measured the cell voltage before tearing off the strip on the nickel end.

At this point, I’m really down on Dell packs, at least the 4+ year old ones. The ones assembled in China have been mostly dead cells, and even the Sanyo assembled packs with Sanyo cells seem below par and have weird design decisions that seem at risk of subjecting parallel cells to different electrical conditions (I may be grasping at straws here for reasons to explain uneven wear).

Just tore apart (peeled the sticker off and the whole case separated) a Dell Latitude P/N 3149C Made in Japan.
14.4V 3000 mAh 8 cells. All had over 3 volts.
Sony Energytec STG US18650S H2

Are these the ones that used to catch fire?

UN 356S1-S1 Laptop Battery Pack.
Rating: 11.1 Vdc
6000 mAh

9 Light Blue Samsung ICR 18650-20 all at 3.72 volts.

was this for an advent or vega product?

Took apart a Dell Inspiron battery pack - J1KND (11.1V; 4400mah; 48Wh). This one was a lot harder to open than my first HP battery pack.
LG LGDAS31865 2200mAH (10A ?) 3.7v cells inside.




Edit: all 6 cells measured ~3,9V. So not bad I guess.

Coming back to my previous pull. 3 cells measured 2V, other 3 - 2.65V. Some guys say that it’s only safe to charge cells that are at least 3V when pulled. How much truth is there? Still waiting for TP4056 charging board I’ve ordered earlier so wasn’t able to try myself. But maybe I shouldn’t if it’s unsafe?

It was like a no name laptop that I trashed. I just made sure that I got the pack model #.

eas has an extensive article on his site explaining how determining cell health from a voltage screening off the pull is can be moot. <2.7V is still caution territory I reckon, but with quality brands like the LGs you pulled may be able to get away with it. Cells manufactured in China like Lishen or EPT may not be so hopeful; just watch carefully for a few red flag observations like heat during charging.

Best way to assess cell health I suppose is to run them through an analyzing charger of some sort.

Thanks for the link, Otanacious.

My current POV is that, indeed, cell voltage from a laptop pull is of limited utility as a screening criteria. There are too many factors that go into it.

Below a certain threshold though, cells from laptop pulls should definitely be pitched. As to what that threshold is, I haven’t found a hard-and-fast-rule. I think ~2.8v is too high, and leads to a lot of perfectly good cells being pitched. I’ve decided to go with 2v as my cutoff and so far, so good.

BatteryU talks about cells becoming irreversibly and dangerously damaged if they stay below 1.5v for a week or more, so 2v leaves a big margin above that. Laptops will slow charge if some of the banks are below 2.8v. The low-voltage threshold given in battery datasheets is for cells being discharged under load, not for self-discharge of resting cells, it has safety margins built in for potential overshoot during discharge.

I’d be much more cautious with unprotected cells that have seen use in a flashlight or similar. In that case, I’d probably pitch them if the voltage was below 2.8v or so, since there is no way of knowing if the low voltage was due to overdischarge under load vs slow self-discharge.

Just cracked open my first laptop battery pack for my very first post. $12 free shipping on ebay. Condition: Used - “BATTERY WILL HAVE 1 OR MORE OF THE TOTAL 3 HOOKS, MISSING BROKEN”

Manufacturer Lenovo
Battery Part # Thinkpad 42T4801
Battery Pack mAh 10.8V 8.7Ah 94Wh - 9 cells
Cell Name LG LGABC11865
Cell mAh 2800

The battery pack itself was a pain in the butt to open up and on the bottom side was a good amount of amazingly hard glue holding them to the plastic case.

For now, some voltage readings:

1 2 3 4 5 6 7 8 9
3.997 3.976 3.987 3.987 3.989 3.986 3.986 3.996 3.997

Average: 3.989 Range: 0.021

I’ll run them through the analyzer and see what we get. I’ll be labeling, re-wrapping, and adding protection circuits to these if they test out good.


image links to album

thread updated thanks shhyguuy

I ripped apart a Compaq Evo N600 14.8V 4400mAh with 8 cells. They are Chinese 18650C4 cells .


OP updated thanks for the post.

Dell Rechargeable Li-ion Battery TYPE C1295
11.1V 53WH
6 cells
CGR18650D
Li-ion
MH12210

Was it a generic pack like the one in the amazon pic you used?

It looks generic like the picture, no branding. Has a made in China sticker on the side. Whoever owned the laptop must have bought a aftermarket pack.

I know, I know! Don’t trust eBay stuff. But, I thought it would be a decent deal, so I did it. I bought what was supposed to be a new, never used Toshiba PA3450U-1BRS laptop pack. It is a 4-cell pack, and the cells are Sanyo UR18650Y L43C, as Jubeldum found in another Toshiba pack a while back. They are 2000mAH cells.

Here’s the problem. I opened the pack and tested cell voltage and got 0.49v for all four cells in series! I thought maybe there was something going on with the balance charger circuit giving me a false reading, so I took it all apart and separated the cells. I got about 0.12v each or so. These are supposed to be brand new cells. Must’ve been REALLY OLD STOCK. |(

So, being the brave, daring (translation: stupid) person I am, I set out to charge them up, thinking that since they have never been used, maybe a jump-start will be all they need. Well, my Nitecore i4 charger just blinked at me, so I pulled them off, and tested about 0.26v on a couple of them. I figured that means the charger was bumping a little bit into them as a check for voltage/charge characteristics was taking place. I thought that looked promising, so I decided to go all out and be as stupid as I could be. I have an old phone charger wall wart that I cut the plug end off of a while back so I could use it as a power supply. It puts out 5.2v @ 1A. I held the loose wires to the positive and negative end of each cell for a little while (less than a minute each) and tested around 2.5v on each cell after that. Looking good! :wink:

So, I put them back in my Nitecore i4 charger and they sat there charging for a couple hours. They got just a little warm, and after pulling them off, they each measured around 3.5v or so. I only took them off because they are as-yet unproven as far as safety, and I didn’t want to chance something happening overnight. I’ll put them back on charge this afternoon and see if I can get them to a full charge. Meanwhile, I’m going to contact the seller on eBay and see how well his/her conscience works. I obviously have “voided” any regular warranty they might have had. But still, the cells were bad and something ought to be done to rectify the situation.

I can report that Milwaukee uses 10 Samsung 20R’s, at least in their 18v 4.0ah “RedLithium” packs.
…………………………
Are there any tool packs known to have 4.35v sells?

Be interesting to see if a cell that dead for that long has any probability of being useful at all….let alone safe. I doubt it IS dangerous, it’s probably too dead.

BTW, you know you can use low amp NiXX charging to bump a low cell up to charging range?