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

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?

I think a lot of people are too conservative in their choice of cut-off voltage for scavenged cells, but trying to charge Li-ion cells that were well below 1.5v for months or years is, to me, sheer madness.

In general, I think NOS packs with anything less than ~2,400 mAh nominal cell capacity are probably too old to be worth the trouble, unless you find it in a recycling bin.

If people are looking for inexpensive packs on ebay, try this $12.95 pack. I haven’t ordered one, since I still have a huge number of NOS and used packs to go through, but it looks a lot like the (now unavailable) $12 NOS Acer packs that have yielded so many nice pink Samsung 2,600 mAh cells. I’ve used cells from those packs that were ~2v (most were higher) when I pulled them and they are doing great.

I need help identifying some laptop batteries.

#1—Lenovo Thinkpad-5.2 AH-10.8v
Battery #’s_LCQM2B8—with a “D” on battery body
Battery Wrap Color_Red with Lt. Blue Tip—(+)

#2—Dell—TK330—56WH—10.8v
Battery #’s_LLLM4C9—-with a “C” on battery body
Wrap Color_Red with Blue Tip—(+)

#3—I don’t remember which battery pack these are from.
Battery #’s__JIUFK17—-with a “D” on body
Wrap Color__Red with Green Tip—(+)

:star: EDIT :——I forgot to mention the Red wraps
are kinda transparent with the #’s printed on the
metal battery bodies. The #’s can be seen thru the
wraps , if this helps to ID them.

I have looked and I can’t find out any info on these
batteries. Can anybody ID these batts or point me
to the right places to look for the proper ID info ?
I also have more batteries , I need to find out the
ID info.

They all sound like Sanyos. I think the red wrap means 3.7v nominal, 4.2v charge termination.
Light blue is probably 2,600 mAh, green might be 2,400 mAh. I don’t know about the Blue, but given the rating from the pack, I’d guess 2,600 mAh too.

Is it just me or does it make sense to get a charger that can give you either iR (Internal resistance) or mR (mean resistance) reading right up front, so we can consider if we even want to put a specfic cell on a charge cycle?

I have had great luck with the LiitoKala Engineer Lii-260 and Lii-300.

for half of what a resistance tester costs I get a charger for free. and with no fan noise.

my $.02

Yeah, I’ve done that before. In fact, that’s what gave me the idea for using this wall-wart to do the same thing. My NimH charger didn’t have slots big enough to stick a 18650 into, so I had to cobble something together with wires and magnets to make it work. This, I just held in my hand, holding the bare leads to each end of the cell. If it hadn’t jumped up in voltage so quickly doing that, I wouldn’t have bothered with them any further. But, to go from 0.26v up to 2.5v in less than a minute made me think it might be worth trying to get a real charge into it, especially since they are supposed to be new, never used. I still have yet to get a full charge, though. I put them back into my charger last night for a few hours, but again had to pull them before finishing, because I’m not going to leave them charging overnight at this point. After last night’s charge, they measured around 4.0v each. I wish I had a hobby charger to test capacity and run-time.

All the 18650 cells I have are pulls from DEAD laptop batteries. The highest any of them tested when I pulled them was around 4.0v, IIRC. But, a lot of them tested below 3v, and some tested below one volt. I even had a really old pack in which none of the cells tested above 0.9v, and I was able to get a charge into most of them. Did I happen to mention I’m partially insane? When I was a kid, my favorite things to play with were the dangerous things. I liked fire, electricity, strong chemicals, and sharp knives. I’m only a little less crazy these days. J) But, let me reiterate that I thought these cells would be NEW and that’s the only reason I bought them. I can’t return them, because I tore the pack apart, so I’m trying to see if there is any hope for them.

I bought a ‘New’ generic laptop pack off eBay and it was completely dead. All 6 (unbranded) cells were reading 0.4v or less. Luckily the seller gave me a full refund without question. Just as well as I had already ripped the pack apart. :wink:
As I had nothing to lose I s l o w l y got them up to 3v using the NiMH setting on my hobby charger, then a normal LiPo charge at 0.5A. All 6 got to 4.2V without getting even warm and all have been working fine in low-amp lights ever since. Capacity is about 60-70% what it should be but as they were free and I have 6 to play with, I’m happy.

Do you know if there’s some place that I can check
to find out the actual Brand name and mah info of
any batteries based on the numbers & symbols that
are printed on them , when no Brand name is ?

Correct this if it is not right but in considering testing/charging laptop pulls in order to get an idea if they are safe or not it would be good to

1) Check if the battery has about 2.5V minimum first. If under 2.5V-toss into the recycle bin.

2) Attempt charging and check the temperature while charging so it does not get too hot. If too hot take off charge and toss into recycle bin (after it cools down).

3) Take out of the charger after at least three hours and measure voltage having let the battery sit about two hours to see if it has retained at least 4.1V. If the voltage has dropped under 3.9 V then toss into recycle bin.

This is considering one does not yet have a charger/tester that can measure internal resistance or capacity (mAh). Later when a charger/tester is obtained that can measure internal resistance and capacity how and where in this example would these fit in?

Also if the new capacity in mAh is not available what should be done?

Does this about sum it up safety-wise?

One other thing is that the flashlight to be used if the batteries turn out all right is a single 18650 light.

The charger will be some simple 18650 charger with one slot and not digital.

Thank you for any advice.

EDIT - Changed minimum voltage.

i think that is good .

I think you are probably wasting cells if you pitch everything below 2.5V. I use 2v as my cutoff.

You should figure out the nominal capacity of the cell © with a little research and pick a charging current that is 0.2-0.5C. For example, for a 2,600 mAh cell, set the charger to between ~500mA and 1.3A. If you can’t find this info to a reasonable amount of confidence then maybe find another hobby, like origami (careful of papercuts though) because between the markings on the pack, the count and arrangement of the cells, should be enough to estimate the capacity, and the cell markings, Google, and this forum should help with verification.

I don’t know where you come up with 3.9v as the cut-off for resting voltage after a charge. 4.1-4.15v is probably more like it. Anything that has dropped to 3.9V is in really bad shape.

Internal resistance measurements from most chargers aren’t very precise/repeatable, and certainly aren’t easily compared to values using other test equipment and techniques. Once you get something that can give you a reading, you should keep track of the results you get and compare it to other results you get, like discharge testing to get a sense of good and bad. Also, for most lithium ion cells the internal resistance is supposed to be pretty consistent over the useful life of the cell, so its not a great fine-grained indicator of cell health.

As for discharge testing results, thats sort of up to you. A cell with less than 70% original rated capacity may not have much useful life left in it, but it may be fine for your purposes. I’ve put a few of them in cheap USB power bank cases and use them to power little USB LED lights.

One thing that I’ve found useful is to use an Arduino + the PackProbe sketch I wrote to dump the data out of laptop packs before I decide tear into them. Once you have it set up, it takes less than 5 minutes to use PackProbe to get manufacture date and cycle count, and often, the voltage of each bank of cells, which can be useful information before deciding to rip apart a pack and subject the cells to more extensive testing. It also adds context to the results of more time-intensive testing.

Are there any known tool packs to source 4.35v cells?

edit: or laptop packs

I don’t recall seeing any, but someone else may chime in.

High voltage cells tend to be focused on capacity, while tool packs tend to use cells optimized for discharge rate. For a given chemistry, cell designers trade discharge rate for capacity by changing the ratio between electrode material, and electrolyte. Moreover, different chemistries lend themselves to one application or another, and the cells used in tool packs tend to use a different chemistry than high capacity cells. I’m not sure, but the specific chemistry may also influence whether high-voltage is a viable technique for increasing capacity, but even if it is, it comes at the expense of durability.

Panasonic and now LG have lithium nickel cobalt aluminum oxide cells that deliver high capacity and moderate discharge rates (~10A) but I think they all have 4.2v charge termination.