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Rebuilding battery packs

Older ThinkPads.. from the 600, the 7xx, the iSeries, 300, 500, the Transnote and, of course, the 701
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goldeneagle
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Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Rebuilding battery packs

#1 Post by goldeneagle » Sat Oct 15, 2016 10:23 pm

Just wanted to see if anyone else has rebuilt battery packs. I'm thinking of investing in a spot welder and rebuilding battery packs for my 360, 755, and 760 machines. Any caveats on the latter two machines, as they have circuitry in the packs?
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

goldeneagle
Freshman Member
Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Rebuilding battery packs

#2 Post by goldeneagle » Fri Sep 08, 2017 11:14 am

As an update to my post, I had a problem after rebuilding my battery pack. The HMM specifies to measure terminals 3 and 4, and that the resistance should be between 3K and 30K ohms. Initially, I had almost no resistance between these two and thought I'd screwed up the internal microcontroller on the battery (because I didn't think to disconnect the ribbon cable when soldering). Nope - I just needed to reseat it.

I can a 755C last night for almost 7 hours on the first full battery charge. I'm using Sanyo batteries (because I didn't want to waste time rebuilding a pack with Chinesium cells. The battery gauge kept fluctuating around 4-5 hours, but the battery life was about as good as I see on my X220T. Which goes to show the benefit of using quality cells from a trusted brand (and the fact that NiMH has matured vastly over the past 2-3 decades).
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

axur-delmeria
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Location: Metro Manila, Philippines

Re: Rebuilding battery packs

#3 Post by axur-delmeria » Fri Sep 08, 2017 1:40 pm

I'm wondering how good the charging/monitoring circuit is inside that old battery pack. I mean, newer NiMH chargers have become "smarter", right?
Daily driver: X220 4291-C91 i7-2620M

Backup: X220 4291-P79 i5-2520M
Toy: X60F Core Solo U1300
In pieces: two retired but working X61Ts
RIP: 760XD 9546-U9E; X61 7676-A24; and a BOE-Hydis HV121P01-100 in failed SXGA+ mod
:cry:

goldeneagle
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Location: Bandera, TX

Re: Rebuilding battery packs

#4 Post by goldeneagle » Fri Sep 08, 2017 2:33 pm

Of course. I don't know how accurate it is, but I'd probably say not that accurate. I remember back when these systems were less than 5 years old, I was seeing about 2-3 hours of battery life, even with almost new batteries. Now, I'm looking at over 5 hours. But also, the chemistry has changed, these batteries are more efficient, and also have a higher capacity (I believe these cells are 2250mAh, whereas the originals were probably around 1500-1600-ish).
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

Saucey
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Re: Rebuilding battery packs

#5 Post by Saucey » Fri Sep 08, 2017 6:36 pm

I've been considering rebuilding the 560X batteries I have. At my work we have an almost unlimited source of batteries to recharge, but I just don't know the right process to do so. Definitely not soldiering them. :eek:
Coffee, ThinkPads & Nikon Fan.

Current: PixelBook, Y50-70, T430
Collected: A31p, T43p, 2521
Past: W700ds, X1C3, 701C

goldeneagle
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Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Rebuilding battery packs

#6 Post by goldeneagle » Fri Sep 08, 2017 6:40 pm

You'd want a spot welder, but you also need to adjust the settings. When I worked for a battery rebuilder, we'd practice on junk cells (cells that were already spent and not holding a charge), so we'd get both the right technique and right settings down (you don't want too high of a setting on a spot welder). The only time you'd ever be using a soldering iron is if you're soldering the tabs on a battery to a PCB.
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

Thinkpad4by3
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Re: Rebuilding battery packs

#7 Post by Thinkpad4by3 » Fri Sep 08, 2017 8:23 pm

I believe that most batteries have soldered tab pairs. You shpuld be able to get the pre-tabbed batteries and solder the tabs.
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The efficiency of two screens equally sized with equal numbers if pixels are equal. The time spent by a 4:3 user complaining about 16:9 is proportional to the inefficiency working with a 16:9 display, therefore the amount of useful work extracted is equal.

goldeneagle
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Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Rebuilding battery packs

#8 Post by goldeneagle » Sat Sep 09, 2017 1:18 pm

Thinkpad4by3 wrote:
Fri Sep 08, 2017 8:23 pm
I believe that most batteries have soldered tab pairs. You shpuld be able to get the pre-tabbed batteries and solder the tabs.
I honestly think that would be unnecessary extra work, especially given how the layout of batteries in a pack is. When I rebuilt batteries for an employer, we would spot weld nickel strips to the batteries. You only solder tabs when they're going to pads on the PCB for the battery. It's been a while since I've spot welded Li-Ion batteries, but I've done it before. Obviously, NiMH is a lot safer.
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

goldeneagle
Freshman Member
Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Rebuilding battery packs

#9 Post by goldeneagle » Sat Sep 09, 2017 5:40 pm

I should be posting photos of my work in progress, but I've never been good in that area. Anyways, I built another pack today. I found with my first pack, that it wouldn't charge in a 750 or 755 machine. It appears to be the same with this pack. Thus, I have a feeling that unless the batteries are fully charged (which the reseller advised that you don't want them fully charged when spot welding), the machine won't find it.

However... I have had luck getting them to charge on a 360CE. Probably because the 355 and 360 used "dumb" batteries (open the battery pack and you have cells, thermistors, and that's it), so it's set to charge and stop when the battery is full. And... it appears to be working. The pack went from 7.25 to 8.06 in about 10 minutes (8V is the minimum, anyways). Now I get to let it finish charging up, and then stick it in a test system to let it run down (which will probably take about 7 hours).
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

goldeneagle
Freshman Member
Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Rebuilding battery packs

#10 Post by goldeneagle » Sun Sep 10, 2017 11:06 am

Sent in a PM, so I thought I would share:
Thinkpad4by3 wrote:
Sun Sep 10, 2017 9:38 am
If you rebuild another battery, can you take some pics or a video showing how you oprn the batteries? Also, do you dremel them open or try to keep them intact with a knife?
I think the first one was opened with a hack saw. The subsequent ones were opened with a dremel. When I worked at batteryrefill.com (horrible company, btw), we would x-ray the battery before opening, so we had an idea how much to cut into it, or not clip any flex cables. And that x-ray machine had NO shielding from radiation, and it was used ALL the time!

They would clamp finished packs down with masking tape and sometimes c-clamps, and then glue with epoxy or a glue gun. Me personally, I prefer masking or quality electrical tape, in the event I'll need to replace cells or any rework again.

Also, and this is one of the biggest pitfalls of batteryrefill.com, DO NOT use Chinesium batteries (the company advertised that it used LG, Sanyo and/or Samsung cells, but in reality, it used no-name Chinese junk that had a high failure rate). If you're going to rebuild a pack, spend an extra $1-1.5 and buy name brand cells (Sanyo, Panasonic, etc). Don't cheap out. Either way, for a 16 cell pack, figure that it'll cost you around $80 in cells. If you shop around, you can get them for $4.50 in quantity, and for 16 cells for a 750 pack, that comes out to $72 sans shipping.
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

Cooler22
Posts: 49
Joined: Tue Jul 25, 2017 2:15 am
Location: United Arab Emirates, Dubai

Re: Rebuilding battery packs

#11 Post by Cooler22 » Sun Sep 10, 2017 11:44 am

Definitely going to use quality batteries if/when rebuilding my 850 battery.

goldeneagle
Freshman Member
Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Rebuilding battery packs

#12 Post by goldeneagle » Mon Sep 11, 2017 3:39 pm

You'll also want to get your hands on a spot welder. You can find them pretty cheap on ebay. Don't expect stellar quality from the Chinese ones, but they get the job done. I will say, i don't trust the soldering iron feature built into it (used it once, but I prefer a temperature controlled soldering iron - heats up quick and I can adjust it how I see fit). If I get time later, I might rebuild another pack, and try and take photos this time around.
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

goldeneagle
Freshman Member
Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Rebuilding battery packs

#13 Post by goldeneagle » Mon Sep 11, 2017 7:39 pm

So, I just rebuilt another pack. One of the leads on the second Klixon thermal cutouts broke, so sadly, I skipped it. I do have one at least. I decided to build this pack slightly differently from before, using electrical tape to hold it in place, and preserving the nickel strips already soldered to the PCB (so I didn't have to do any soldering). Had a few problems with some of my welds (and I'm not using the best spot welder in the world, anyways). Before putting the top cover on, I checked it with my Fluke multimeter - voltage was about 6.8V (8 is the minimum according to the HMM), and resistance between terminals 3 and 4 was about 9.62K ohms, which is within HMM spec (3K-30K I believe). I put it in the 360CE to charge, as the 750/755 won't charge a newly rebuilt battery. About 10-15 minutes in the 360CE, and voltage is now at 8.45V, which is very promising. When the battery is fully charged, I'll probably have it run a screensaver or something to wear down the battery, as, with the past two packs, it'll be 6-7 hours before it needs to be recharged.
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

goldeneagle
Freshman Member
Posts: 107
Joined: Sat May 31, 2014 8:06 pm
Location: Bandera, TX

Re: Rebuilding battery packs

#14 Post by goldeneagle » Tue Sep 19, 2017 5:05 pm

Another update - successfully rebuilt a 760 Li-Ion pack. Amazingly, I was able to get the same brand and model of cells as the original pack's cells (Panasonic CGR17500). It's still charging, but at 4%, I unplugged it briefly and it did hold its own. Now I get to charge it all the way up and let it drain down. I'll see if I can't run a battery logging program on it, so I can actually see what kind of runtime I'm getting, though I need to figure out what I need to do so the computer is operating under a load. This also means BIOS updates on the 755CX and 755CDV.
Historic ThinkPads owned:
300, 360C, 360CE (x2), 360CSE, 510CS, 560, 560E, 701C, 701CS, 730TE, 750, 750C, 755C (x3), 755CE, 755CX (SVGA), 755CDV, 760ED, 770
Newer ThinkPads owned:
T520, W520 (x2), X220 Tablet (x4), and some T61/X61T laying around somewhere

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