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850 battery replacement

Older ThinkPads.. from the 600, the 7xx, the iSeries, 300, 500, the Transnote and, of course, the 701
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macos_2017
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850 battery replacement

#1 Post by macos_2017 » Tue May 09, 2017 11:43 am

Has anyone managed to restore an 850 battery? I have two dead ones...
Also is the 820 battery compatible with the 850?

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Last edited by macos_2017 on Tue May 09, 2017 11:43 am, edited 1 time in total.

Thinkpad4by3
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Re: 850 battery replacement

#2 Post by Thinkpad4by3 » Tue May 09, 2017 11:58 am

Just don't screw up, or you' ll have a 1/850 chance of finding another one :-) most batteries are very similar so taking it apart shouldn't be a pita.

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Probably should be Thinkpad16by10.

Looking For: 386 laptop, IBM or not.

fultontech
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Re: 850 battery replacement

#3 Post by fultontech » Tue May 09, 2017 12:04 pm

There are a couple of issues in addition to dead cells that have made refurbishing the battery impractical.
The largest obstacle seems to be the physical circuitry that stops the unit from being recharged (over charged) once the voltage drops below a set point. I have read that people have bypassed this safety measure from the manufacture, though I don't recall where.
The intelligent programming stored in the battery was lost when the charge finally dissipated. There is no way to recover the original programming for the 800 series batteries. Someone could guess at what was there and write something, then figure out how to get the program onto the battery controller board.
IBM P75
IBM ThinkPad 700, 720C, 750Cs, 360C, 360P, 360CE, 360PE, 730TE, PC110, 365CSD, 365ED, 701Cs, 820, 600X, 770X, 240, T30
IBM RS/6000 43P 150
Lenovo ThinkPad X41T, X61T, X200T, X201T, X220T, X230T
Lenovo ThinkCenter M92p Tiny, M900 Tiny

macos_2017
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Location: Athens, Greece

Re: 850 battery replacement

#4 Post by macos_2017 » Tue May 09, 2017 12:21 pm

I just source a new boxed 820 battery...anything is should do before using it?


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fultontech
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Re: 850 battery replacement

#5 Post by fultontech » Tue May 09, 2017 12:24 pm

I purchased old stock sealed boxes before. It's most likely dead. The safety circuitry I wrote about before won't allow the battery to be charged.
IBM P75
IBM ThinkPad 700, 720C, 750Cs, 360C, 360P, 360CE, 360PE, 730TE, PC110, 365CSD, 365ED, 701Cs, 820, 600X, 770X, 240, T30
IBM RS/6000 43P 150
Lenovo ThinkPad X41T, X61T, X200T, X201T, X220T, X230T
Lenovo ThinkCenter M92p Tiny, M900 Tiny

goldeneagle
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Re: 850 battery replacement

#6 Post by goldeneagle » Thu Sep 07, 2017 8:36 pm

I'm interested in this thread. Because I don't know where to look to get old batteries, I've been collecting some 755's here and there to stock up on batteries. I'd like to try and rebuild another battery or two (750-series packs). I don't know if I screwed up one, although I think the thermistor (thermal protection) might've been blown while soldering. I had to do it, but it's tempting to bypass that as well, since it takes a fair bit of time to build a new pack (using a spot welding machine).

As for intelligent programming stored in the battery - I would be inclined to think this was stored in ROM; I know newer batteries will have an EEPROM that stores that stuff (manufacture date, last used date, capacity, charge cycle, etc). I don't think they really had all those capabilities back in the mid-90s, though I could be wrong.

Just make sure if you rebuild, don't skimp out and get crappy no-name Chinesium cells. I spent a little more and got Sanyo cells (IMO, always one of the best brands you could get, followed by LG).
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: 850 battery replacement

#7 Post by Thinkpad4by3 » Thu Sep 07, 2017 8:45 pm

Dont bypass the thermistor. Many battery packs rely on the battery temperature to cut off charging. Its an effective method of charging NiCD and NiMH batteries.
Probably should be Thinkpad16by10.

Looking For: 386 laptop, IBM or not.

goldeneagle
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Re: 850 battery replacement

#8 Post by goldeneagle » Thu Sep 07, 2017 9:04 pm

That was a quick reply! Okay, so in the HMM (for the 75x series anyways), I remember reading to check 2 terminals, and that resistance should be a certain value. I forgot to remove the smart battery PCB before soldering. Anyways, the resistance is way out of spec with what the HMM says. Is this something that could be related to the thermistor being bad?
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
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Posts: 107
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Location: Bandera, TX

Re: 850 battery replacement

#9 Post by goldeneagle » Fri Sep 08, 2017 2:28 am

Not sure if this will help for your 850 battery, but I managed to get my rebuilt 750 series battery to work. Turns out all I needed to do was make sure the flex cable was fully inserted into the microcontroller PCB inside the pack (IBM refers to it as a microprocessor, but whatever). Anyways, I did that and it worked, but I still had some issues. Had to charge it up in my 360CE. Turns out it wasn't making contact to all the terminals for whatever reason. Now I'm having it run one of the demo programs to kill the battery (so I can recharge again overnight).

I don't know if the 850 had any demos that came with it, but I'm sure you can find ways to run the battery down, once you rebuild your pack (run fsck in AIX, or have it do complex mathematical calculations).

So as a recap - I don't think you'll have any problems with the microcontroller, so long as it's a NiMH pack. More intelligent circuitry (like charge cycles and preventing charging if the battery cells go completely dead) didn't seem to become mainstream until the LiION era.
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

macos_2017
Posts: 6
Joined: Mon May 01, 2017 12:37 pm
Location: Athens, Greece

Re: 850 battery replacement

#10 Post by macos_2017 » Fri Sep 08, 2017 1:55 pm

@goldeneagle many thanks for the post...very insightful indeed..will post my progress as well


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