Sounds like you’re right on top of things.
Welcome to the world of Free 18650 Batteries!
Your triage process should safely cull any bad 18650s, and if they pass that & hold a charge for a few days (unused, of course), and deliver ~the nominal capacity, I’d tend to trust them.
Please allow me to politely provide you with a means to RTFM. The inventors of the technology were pretty thorough, IMNERHO. This, combined with your process, should help you answer your own questions.
Dim
Wow! Thanks so much for the warm welcome and the link the the manual. Nice to have access directly to the source, so to speak. Going to take some effort to wrap my brain around it, but the safety portion seems to be quite understandable to the layperson.
I also just scored some (6) NOS 12” iBook battery packs. Haven’t cracked any open yet, so no news on what’s inside, however I did place one in an iBook and it took the charge fine, reporting full charge and ran the iBook for a few hours on full power mode, so I’m pretty optimistic. Based on form factor and output voltage, it should have 6 18650s per pack. Now I just need to decide what to do with them. 
Thanks again, Dim. A pleasure to be here and thanks to everyone who’ve contributed to this valuable community resource.
Mahalo
I finally got around to disassembling the NOS 12” iBook pack my previous post. BTW, I see a lot of people using dremel tools, etc… to break into these cases. I haven’t read through the whole thread to see if anyone else is using the method I use, but for the most part, I’m able to get into these packs with my bare hands and just a few hand tools in the end (leatherman and diagonal pliers), applying very minimal forces on the packs.
Table Data and pics before disassembly:
Apple, M9337G/A, mAh not listed but calculated as 5100 mAh (2x2550)@10.8 v (3x3.6), SF (Sony Fukushima?) US18650GR, 2550Mah
Based on the output voltage (10.8v) I’m expecting 3 cells (3 x 3.6v). Based on the dimensions of the pack, I’m expecting 6 18650s, so 3 pairs (3x3.6v), each pair welded in parallel (2x2550mAh). Volts and Amps multiplied gives us wattage (Power), so total power output in the range of 18.4 watts (18.36 rounded up).
Disassembly:
Most of the battery packs (HP/Apple/Dell/Asus/Acer/Toshiba) that I’ve examined to date are built in this fashion: Basically the main frame is a skeletonized plastic clamshell with a large window (ribbed or not) which is sealed by a thin, stick-on plastic or metallic plate. In the picture below, if you look at the upper right corner of the cell, you can see where I’ve folded back the corner of the plate, revealing the green battery inside the pack. Funny coincidence, in the youtube video by Ol-Lumen in the OP, he disassembles what looks to be an Acer Netbook battery which does NOT have the plate I spoke of.
Peeling back the plastic plate completely reveals:
Using my fingers, I was able to pry open one side of the ribs, tear it free, then work the remaining ribs off, revealing the batteries below:
Flipping the pack over, by flexing the pack slightly, I was able to remove the cover on the bottom of the pack:
With the inner ribs removed, I then pried off one of the long side retainers, which then allowed me to carefully extract the two pairs of inner cells.
I used the diagonal pliers to trim the leads to avoid shorts and then removed the last 2 cells. I used the needle nose of my leatherman to remove as much of the welded battery tabs as possible. I then used a sanding drum on my cordless drill to remove the remnants (because I couldn’t find my dremel). In this battery pack, Apple uses a silicone based compound as an adhesive, which made clean up a breeze. A little spit and elbow grease and we have the finished product:
Note that the battery pairs are welded in parallel, positive to positive, negative to negative. This doubles the current capacity, basically turning two 3.7 v x 2550 mAh cells into effectively a 3.7 v x 5100 mAh cell. 3 of these paired cells are then wired in series (positive to negative) which then triples (3 cells) the pack voltage (Apple uses 3.6 volts in their calculation, apparently, so 3 x 3.6) to 10.8 v.
Imprinting on the cells:
SF US18650GR
T G7141OI12I
Based on the 20th post in this link, I’m assuming these are 2400 mAh batteries, build date 2006, September 12.
Charged the individual cells via leads connected to my Opus charger, then ran a capacity test which yielded the following mAh/internal resistance results:
2544/103 2535/97 2501/116 2569/98 2549/96 2507/90, with all batteries charging up to between 4.17-4.19 volts, so I’m pretty happy with the results.
BTW, I’ve been doing this for a few weeks now so still very wet behind the ears. Initially, I was recording data directly onto the batteries, however I was noticin a couple of issues. It was difficult to write on the round batteries. I could only record limited data. The permanent marker I was using was rubbing off easily.
To address these issues, I created a google sheet into which I recorded what I considered to be pertinent information. I wiped down each battery with rubbing alcohol to remove any possible grease, and then I assigned a 2 digit hexadecimal code for each battery which I wrote on each battery using metallic permanent marker. I then covered the marking with a piece of clear tape. You’d be surprised how long that will protect such markings.
Anyway, I made a copy of my spreadsheet and it’s available to the public for comment here. I would appreciate any comments or feedback. Also, if anyone else finds it is useful, by all means, feel free to make a copy for yourself and distribute it freely.
For now, the batteries go into a holding plastic container, placed in a firesafe. In 5 days time, I’ll check the voltages against my data table to compare losses.
Mahalo
Latest project, my dead Ryobi One 18v Li-Ion battery pack.
This pack yielded 10 Sanyo UR18650SA L38A, which apparently is an IMR cell w/ 1300 mAh capacity
I haven’t had the opportunity to check the cells yet.
Mahalo
I want suggest to eveybody this amount of laptop batteries, they are too many for me, I have 2 x 18650 single cell flashlight and 18 Sammy 28A
Just wanted to say thanks for the detailed writeup and pictures! Very helpful for those of us who are also relatively new to this game. (I’ve dissembled one pack from an old Asus for 6 good Samsung cells, and have another Lenovo at home that I haven’t cracked open yet.)
I bought a laptop bat pack that proved to be defective with my laptop so I harvested the cells. At first, they looked good… decent initial voltage, charged to 4.2V (w/XTAR SP-1) and capable of delivering 4+ amps with a DD Ultrafire C2-T6 but over a week, it looks like they self-discharged 0.04V. Please take a look at the pics to see if you’ve seen these cells before but the data table may help make the conclusion to ‘Discard or Keep’. Thank you for your experience/opinion!
!
http://s1007.photobucket.com/user/broodmasterpb/embed/slideshow/FP%2018650%202000mAh%20150924
!
You are very welcome, sir. Still pretty green here myself and hoping to learn more as I go forward.
Good luck with your pulls.
Mahalo!
Model: 2x Dell XX237
3S2P 11.1v 60Wh (5400mAh)
12x Samsung ICR18650-28A. All cells good :)
I made a very good friend at work the other day, the electronics disposal guy. He picks up old laptops and desktops/monitors/keyboards and disposes of them. I chatted a little bit and told him I was looking for laptop batteries, he said he would keep an eye out for some. Today was the first delivery: 3 Dell packs Type T54FJ, 60Wh, 11.1V. Tore one apart at lunch and found these NCR18650. Will see what voltages are when I get home.
UPDATE: All 6 cells in one pack tested at 3.96V, so hopefully these are still pretty healthy!
Tearing them apart is a bit addicting .I liken it to opening christmas presents.
just remember to always peel the labels first .
happy hunting
Opened my second-ever pack today.
From a ThinkPad X120e, pack is part number 42T4787 / 42T4786, labeled 10.8V, 5.2Ah, 57 Wh.
Cells are Sony US18650GR (review here ), spot-welded in a 3S2P arrangement. There’s a little bit of glue or sealant around the cells, but it didn’t stick them hard to the pack casing. The back and sides of the pack are stuck tight together (plastic-welded or glued?), but the front (near the contacts that plug into the computer) was easy enough to pry apart, starting at the spring-loaded tabs on each side.
Exact text on cell:
This pack was giving an error on the computer when it was under warranty, so Lenovo sent a new one. Haven’t tested or attempted charging any individual cells yet, but I’m hoping there’s only one or a couple that are bad. Current plan (after an initial voltage check) is to take my charger outside for the initial charge attempt. As I understand it, the first charge (after cells have been sitting a while) is riskiest, so if they survive that and hold a charge, I’ll put them into rotation with my lights.
Hope this is helpful,
Andy
Hey guys, great info. On this thread.
I have a favor to ask but im not sure if possible. I live in mexico and i’m just getting into the whole 18650 cell flashlights and diy projects but out here i cant get decent cells. Most pc repair shops will sell the packs at brand new prices and once you explain what’s inside it’s even worse.
I’ve been eyeballing a lenovo 9 cell pack on ebay for 16dlls but i was wondering if any of you would be willing to sell me 2 lenovo 6 or 9 cell packs for the same price, just wondering.
Hi, Ansarogu,
The trick to PC repair shops is not to ask for New. Their contribution to this method is to store “dead” packs for recycling. That’s where you come in. You’re there to make a Friend and help defray his storage and disposal costs. And to do a lot better job of recycling than the “official” methods!
I cannot imagine any retail establishment, in Mexico or Valhalla, that would cut their prices for any reason other than the usual Free-Market constraints. You could try this approach: “I don’t like Bob’s Computer Store, but they sell this same battery for $12.95” (pick a computer store across town & a number you want to pay) “Can you let it go for that, if I promise to become your newest best customer?”
The “dead” factory packs (not necessarily the “compatible” ones) still have the best batteries that were available from the best manufacturers at the time they were made. Usually they “die” because the circuitry fails somehow. Yes, you can expect some dead 18650s, but they tend to be the exception.
Hi, thanks for the tip. I’ll find some more repair shops, see if any have good deals on battery packs. One thing to keep in mind down here is that the recycling programs are non existent. And if they figure that a good quality cell (new of course) goes for 6~9 dlls, then the price for a used battery pack (in any condition) goes up to 20 or 30 dlls, assuming. 3~4 dlls per used cells, simply because of the number of cells you would get. It’s really bad hahaha.
But thanks!
Do they pull the 18650s out of the packs for you? Or clean the weld spots off? Or give each 18650 an initial charge & test? What charger do they use?
A bad pack is a bad pack. It only becomes a bunch of used 18650s if someone invests more labor capital in the conversion process. And then they’re used 18650s. Tell them to eat their bad packs, you’re going to “Bob’s Computer Repair” from now on.
If you don’t have other computer stores near you, how close are they? I’ve found that (after you determine they have bad packs) explaining how to extract the 18650s puts them in a more receptive frame of mind than starting with the ‘why’. This is also a good time to explain the care required to use, charge & maintain 18650s; and to mention some of the better “vent with flames” stories.
You might also find some of your neighbors with bad laptop batteries, who might appreciate you picking them up for “proper disposal”…
Lol yeah right, i doubt they even have knowledge to do such testing.
I just pulled the trigger on a Lenovo 9cell 94wh, 87ah (81ah minimum) battery pack from Ebay for 13dlls. Doing a bit of math throws out 2700mah for each cell on minimum, taking the “used” part into consideration im guessing 2300~2500mah for each cell. I hope. :-/
Would you consider the Xtar vc2 a decent charger to charge and get an estimate on the mah capacity?
Thanks!
I don’t use one, so I’ll leave you with the expert’s conclusion. His other charger reviews are here.
Pulled 6 cells of Panasonic CGR18650CG 2250mah from an ACER AS10D51 pack.
Edit: 4400mAh, 10.8V all were at 3.9V
Ansarogu,
I like the LiitoKala Engineer Lii-500 charger. when dealing with “old” cells it is really handy to have an internal resistance measurement that way you can minimize the time spent on a charger for (at that point an known substandard) cell.
I draw the line an 3x of the same cell new internal resistance measurement or if I have a lot of cells 2x to find the best of the used ones.
Much safer and faster then charging cells that clearly are not up tot he job any more.