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IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

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ReCreate
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IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#1 Post by ReCreate » Wed Jul 13, 2016 10:52 am

Recently I've gotten a few old thinkpads and have lots of spare 3100 mAH cells lying about, thought i'd document the process of re-celling thinkpad batteries.

Re-Celling or Battery Rebuilding is the disassembly of laptop batteries for the purpose of replacing the individual cells with new ones, making it now work as good as it did when it was new, if not significantly better. (Li-Ion battery tech has gone up 30+% in power storage in the unchanged 18650 form factor over the past 5 years alone)


The method I use for disassembling the batteries is to get a pair of snips (My favourite type is the sidecutters) and bite on a corner of the battery pack's plastic enclosure. This will sacrifice the aesthetic appearance of the battery so you should do it on a corner that isn't exposed when the battery is installed. Then you use a flat screw driver to pry the top and bottom halves of the battery apart. For more stubborn batteries, knives, hacksaws and dremels will be used. Be careful about stabbing batteries, but don't worry to much, they don't explode, they only release toxic fumes. (from experience :D ) So do it outside if you need to use any of these more aggressive tools.

Tips and tricks:
1 You do not need to put all the original cells it had back in. Cells in parallel can be omitted, so long as the series-configuration remains the same. A 3S battery can run with 3 cells, 6 cells, 9 cells and so forth. Cells put in parallel become one big virtual cell.

2 The cells you put in SHOULD be identical cells. Identical type, age and wear. You can get away with using different batteries, but beware, the entire pack is limited by the power of the weakest link!

3 Good cells can be harvested from HP, Dell and modern Lenovo laptop batteries for cheaper than buying the cells outright. Each cell can cost as much as $7 new. Second hand batteries can get you better deals.

4 You can solder directly onto batteries safely. You need a nice soldering iron with a HEAVY TIP! Flat tips are ideal. Soldering iron does not have to be high power, it just needs a high thermal mass on the tip!

5 Positive terminals solder much quicker and easier than negative terminals. Put a bit of flux and scratch the surface of the negative terminal before soldering. Do not hold it on there longer than a few seconds!

I'll also put the images on IMGUR for future-proofing in case if the forum's image hosting goes down.

Wiring diagram for R30 R31 R32 thinkpads
http://i.imgur.com/g0i6ZUU.png

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http://i.imgur.com/m0uBoo4.png
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Shredder11
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Re: IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#2 Post by Shredder11 » Wed Jul 13, 2016 6:49 pm

Maybe you could create a video showing your tutorial in action, and upload it to YouTube?
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Re: IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#3 Post by ReCreate » Wed Jul 13, 2016 10:54 pm

Shredder11 wrote:Maybe you could create a video showing your tutorial in action, and upload it to YouTube?
Good idea. I've run out of batteries to rework at the moment but if I get more I'll do that.
Proud owner of: IBM A22M, IBM R30, IBM X41T, IBM X60, Lenovo T400, Lenovo X200S ... and Texas Instruments Extensa 512 :)

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Re: IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#4 Post by evening_hunger » Thu Jul 14, 2016 6:51 am

Weren't there any considerations about soldering directly on the batteries as they could explode due to temperature?
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Re: IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#5 Post by rkawakami » Thu Jul 14, 2016 2:29 pm

Correct. Lithium ion batteries do not like excessive heat. Batteries that already have solder tabs welded to them may be a little bit safer, if you can clamp a heat sink between the end of the tab and the battery end. Applying an iron with high thermal mass directly to the terminals could result in an explosion,
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Re: IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#6 Post by zoltan87 » Fri Nov 24, 2017 6:25 pm

What about the control board in the battery, will it learn and adjust to the new capacity automatically after re-celling? I am pretty sure I read it somewhere that after someone re-celled an old battery, the new laptop battery worked, but it wasn't quite "right", probably it would have needed a re-programming? There is so much conflicting information out there, it's very confusing.

I am quite surprised, that by now still no-one has put together a comprehensive guide how to re-cell certain older Thinkpad batteries.
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Re: IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#7 Post by MustardOrMayo » Fri Feb 23, 2018 8:49 am

zoltan87 wrote:
Fri Nov 24, 2017 6:25 pm
What about the control board in the battery, will it learn and adjust to the new capacity automatically after re-celling? I am pretty sure I read it somewhere that after someone re-celled an old battery, the new laptop battery worked, but it wasn't quite "right", probably it would have needed a re-programming? There is so much conflicting information out there, it's very confusing.
At least the T4x/R5x series battery packs need to be reprogrammed, but laptop battery packs whose respective models are from 2002 and earlier can probably be rebuilt easily. The newest laptop I was able to rebuild a battery in is a Compaq Evo N410c, which is from around 2002 or so.

I did get someone to rebuild a T4x/R5x series battery pack, but the battery level reported to the OS is stuck at 0%, TP Power Manager reports that the battery still has a 4% charge capacity (incorrect), and the battery indicator on the status LED array continuously blinks amber.
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Re: IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#8 Post by NonesensE » Fri Feb 23, 2018 10:39 am

One very important thing to keep in mind is that you have to balance the new cells before soldering them in parallel. Simply put them in parallel with a 10 Ohm or so resistor in between and leave them this way overnight. Otherwise, the unregulated balancing current may result in fire. Happened to me because I trusted everyone telling us those cells are safe even when shorted. They aren't.

For re-celling the battery on newer thinkpads, there are two possible strategies. The first one is only applicable when your battery isn't declared dead by the battery controller: Solder the new cells in parallel to the old ones and cut out the old ones afterwards. This is easier with two or three cells in parallel: cut one out, solder in a new one, cut the other(s) out and solder in the rest.

This way, the battery controller will never see a 0V cell so after recalibration, the battery should work like new or better (will probably take several recalibration cycles as the controller is said to be bad at increasing the capacity). It's possible though that the sudden improvement trips some security feature in the battery controller so that it trips the fuse. In this case, you have to reprogram the battery controller and solder in a new 3 pin fuse like in the second strategy:

If your battery is already dead or you don't want to solder in tight places, first look for the 3 pin fuse and lift the trip pin if the fuse is still intact. Otherwise, the battery controller will blow it in the process and you need to solder in a new one. Then cut out all the cells, solder in the new ones and reprogram the battery controller like shown in this thread:

viewtopic.php?f=30&t=124273

After this, don't forget to solder the fuse pin (or a complete new fuse) back on.
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Re: IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

#9 Post by Thinkpad_enthusiast » Fri Aug 03, 2018 10:14 pm

Thank you to the authors of this posting. I have yet to rebuild a battery pack but that is not a question of "if" but a question of "when".

It would be helpful if posters, who have replaced the 3-terminal fuses, would give a part number and manufacturer of the replacement fuses. I have opened the battery pack for a R40 thinkpad and see no part number on the original fuse ...unless its on the underside. Some time ago I searched long and hard on the internet for these fuses and no-one, that I could find, has given a part number or manufacturer. All the posted photos show no part number.

The fuse is given different names. I have seen it listed as
"3 terminal fuse"
"self control fuse"
"self control protector"
"self control link" -- not sure on this anymore...memory fade.
"battery protector"
You can substitute "controlled" for "control" if you do searching to get the most results. Both forms are used on websites. Try "chemical fuse" if you are desperate for more results.

As best as I could find, there are 2 (or 3) manufacturers of these devices.
* Sony Chemicals Corporation (Sony Corporation) --> Dexerials
* Schott
* sorry my memory has faded on the possible third manufacturer

My dismantled R40 battery pack's fuse has a single equivalent heater element with resistance of 52 ohms. In an equivalent model the heater element goes from the control terminal to the center tap of the 2 series fuse elements. If that is not clear then take a look at Dexerial SFJ series devices to see what I mean. The Dexerial devices have much lower heater resistance so may not be usable substitutes. Also, mechanically, Dexerial devices are not similar (but adaptable). The Schott manufactured battery protectors D6T-S1 and D6X are a match for heater resistance and are very similar mechanically. Here are some webpage URLs to look at:-

https://www.us.schott.com/epackaging/en ... _type.html
https://www.us.schott.com/epackaging/en ... pe/d6.html

Regrettably, the technical specifications are seriously incomplete...even for a shortform datasheet. It looks like something from the marketting department and not the engineering department.
* Firstly, the 32V rating is almost certainly the maximum guaranteed interruptable voltage difference across the two fuse terminals and not the heater voltage needed to rupture the fuse. That should have been explicity specified as is done by Dexerials.
* Secondly, there are no specifications for the minimum heater voltage (with ambient temperature condition) that guarantees fuse rupture. Even for a short form datasheet that is a serious omission.

Note that, unfortunately, these fuses are going to be discontinued in Sept 2018.

I do see suppliers listed on Alibaba and Aliexpress with indicative pricing around the $US0.61 per piece for a 10 piece lot (but price is unconfirmed).

Incidentally, the R40 battery pack has 18 clasps that hold it together. Some of those clasps have silicone rubber in them which makes things even more difficult to release them. I have not worked out a good way of opening those packs so they can be easily re-used. I have had several battery packs that committed suicide (by blowing the fuse) simply because they were left in the laptop in storage for too long and over discharged. Except for the blown fuse, those packs are perfectly usable as you can find out by accessing the +ve terminal of the series'd cells inside the pack and rechargning them directly. I drill a small hole into the body in just the right place to access that +ve terminal with a pin. (Sorry I dont have a photo uploaded showing where to drill it.) The negative terminal is avaliable on the pack's connector.

R40 battery pack
microcontroller:- Mitsubishi 37516
EEprom:- 80AM (AK6480A??)
battery monitor IC :- M62150FP (Misubishi ??)
thermistor: 34S (??)
Thermal protector (resettable fuse) : BPD2 (Uchiya)

There does not appear to be anything on the battery monitoring IC side to balance the state of charge of each (parallel paired) cell in series. As usual,complete datasheets for some parts are not readily available.

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