IBM Thinkpad Battery Re-Celling Battery Rebuild Tutorial

[ReCreate]

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 ) 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

Wiring Diagram for A22M A21P A22 & Others
http://i.imgur.com/m0uBoo4.png

[Shredder11]

Maybe you could create a video showing your tutorial in action, and upload it to YouTube?

[ReCreate]

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.

[evening_hunger]

Weren't there any considerations about soldering directly on the batteries as they could explode due to temperature?

[rkawakami]

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,

[zoltan87]

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.

[MustardOrMayo]

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.

[NonesensE]

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.

[Thinkpad_enthusiast]

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.

[ReCreate]

Hey there Thinkpad_Enthusiast

I've recently completed a re-celling on a Thinkpad X200S running Windows 10, replacing the 9 original cells with brand new Samsung INR1865029E.

You can simply disconnect the ultimate positive and negative and rebuild the pack separately and then later re-connect it. This worked in my case. My old battery was storing less than 10 wH and now i've got 95 wH.

One problem though, these new batteries on newer thinkpads don't go by voltage to determine capacity. It tries to shut off when it uses up the 10wH of energy.

After manually overriding the critical battery action, i've gotten it working (on windows 10).



I've written a little python program to show me the state of charge based on just voltage alone. It seems accurate enough. The app on the right uses the windows API to determine state of charge. (which gets stuck at 4.5% after the first 9.5 wH gets used up)

If anyone's interested in it they can PM me I guess. But this goes to say that re-celling can definitely work even on modern laptops.

edit:
Here's a picture of the battery with the new cells in it.

https://i.imgur.com/EAAD10R.jpg

FORUM warning:
picture WAY too big, tags removed.
Please read the Forum Rules, especially Section 5: viewtopic.php?f=16&t=14339

Do note, it takes a lot of skill to do this correctly. Soldering batteries is part of my job. (and yes, it CAN be safely done with a soldering iron and lead-based solder) But as the other guy above said, you don't want to heat up the cells. They won't explode (unless fully charged), instead they will have a thermal fuse within them break, bricking them forever. I can apply solder to the cells (both sides of it) in 2 seconds. You don't want to have a soldering iron applied to the cell for more than 5-10 seconds.

[kfzhu1229]

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.

I have tried rebuilding a A30 battery pack, and the circuit shuts down the power and couldn't get it back on. It acts as if the battery fuse on the computer's motherboard has blown out, but it's definitely not the computer at fault as it still works with another battery pack of mine.

[Thinkpad4by3]

I have tried rebuilding a A30 battery pack, and the circuit shuts down the power and couldn't get it back on. It acts as if the battery fuse on the computer's motherboard has blown out, but it's definitely not the computer at fault as it still works with another battery pack of mine.

You have to jumpstart the pack.
https://hackaday.com/2011/08/01/who-kne ... ump-start/

[kfzhu1229]

You have to jumpstart the pack.
https://hackaday.com/2011/08/01/who-kne ... ump-start/

Oh okay this makes sense, but would that jump start apply to all batteries since mine is not a T4x battery (though I will do a rebuild of that too sometime)

[goldeneagle]

I think I need to write my own FAQ, but you should NEVER solder directly to a battery. That's why you buy a spot welder. You can get a Chinese one for under $200, and it's much safer than soldering to cells.

[steveadorjan]

Sorry for reviving this old thread, but I wonder if anyone could help me clarify the following question: If an original Lenovo Thinkpad battery is re-celled by a dealer, do I have any way to check this without actually opening the battery? For example, will the Power Manager (I still use Win7 on my X220) battery info show this or not? Power Manager does display the manufacturer (e.g. Panasonic or Sanyo or LGC), the date of manufacture, the number of cycles, date first used and so on.

The reason I'm asking is that I want to buy a X220 battery on ebay (UK) and the seller (a shop with 99% rating) describes it as genuine, original, brand new (though NOS, made a couple of years ago) Thinkpad battery with the correct FRU and everything but says it is "open box", that is, it's supposed to be new, in the original Lenovo box, but not sealed. Since the price is quite low (about 50% of similar ones in sealed box), I'm afraid it might have been tampered with (re-celled, hacked, who knows). But if I can check this with Power Manager, I'd take the risk and order, since in the worst case, I can file an ebay complaint

[dr_st]

Sorry for reviving this old thread, but I wonder if anyone could help me clarify the following question: If an original Lenovo Thinkpad battery is re-celled by a dealer, do I have any way to check this without actually opening the battery? For example, will the Power Manager (I still use Win7 on my X220) battery info show this or not? Power Manager does display the manufacturer (e.g. Panasonic or Sanyo or LGC), the date of manufacture, the number of cycles, date first used and so on.

Power Manager reads data from the Battery EC. Someone who is sufficiently advanced can tamper with that information, so you won't be able to trust anything anyways.

If the battery is completely fake, you will usually find that Power Manager reports FRU/Serial different from what's on the battery itself. But if it's genuine, but recelled - not sure.

The reason I'm asking is that I want to buy a X220 battery on ebay (UK) and the seller (a shop with 99% rating) describes it as genuine, original, brand new (though NOS, made a couple of years ago) Thinkpad battery with the correct FRU and everything but says it is "open box", that is, it's supposed to be new, in the original Lenovo box, but not sealed. Since the price is quite low (about 50% of similar ones in sealed box)

50% for an open box sounds reasonable to me without any tampering/hacking. Why would a shop with 99% rating tamper with batteries anyway?

[steveadorjan]

Thanks for your insights. Of course, I don't think the shop would waste time re-celling old batteries just to sell them for a relatively low price. But I'm wondering about whoever the supplier to the ebay store was. Since they are open box, I'm not sure they were actually sourced from Lenovo. It could have been anyone for all I know.

[omero72]

Thanks for your insights. Of course, I don't think the shop would waste time re-celling old batteries just to sell them for a relatively low price. But I'm wondering about whoever the supplier to the ebay store was. Since they are open box, I'm not sure they were actually sourced from Lenovo. It could have been anyone for all I know.

If it sells at a very low price, i.e. 50% of the original part, then it must be non-original or, as you suspected it must be tampered with or anything else which will justify the lower price. Don't believe what the seller says too, particularly if they are new or recent sellers.

[L29Ah]

Just recelled an aftermarket 9cell X201 battery. The case had to be vandalized to open up and then fit the bulky 18AWG wires in, so now it's holding on duct tape. I should have made and used a cell welding device instead probably, since the nickel strips are so much thinner.

[zoltan87]

Just recelled an aftermarket 9cell X201 battery. The case had to be vandalized to open up and then fit the bulky 18AWG wires in, so now it's holding on duct tape. I should have made and used a cell welding device instead probably, since the nickel strips are so much thinner.

Would be great if after a few discharge cycles you could come back and report on the battery, particularly how accurate the battery percentage level is in windows, does the lenovo power manager utility reports the increased capacity, and how long does one charge last on average. I still have a couple of good batteries, but all these leftover batteries will sooner or later die.
So collecting the info for a future re-celling adventure.

[Radioguy]

Haven't dusted one off in bit, but I assume there's still no source for 760 series batteries? I considered recelling one, but stopped when I wondered if the Ni-Mh or Li-Ion was was easier to do, and if it was possible to improve on the original design.

What would be the best option to get a 760 portable again? Recelling a Li-Ion?

[axur-delmeria]

Haven't dusted one off in bit, but I assume there's still no source for 760 series batteries? I considered recelling one, but stopped when I wondered if the Ni-Mh or Li-Ion was was easier to do, and if it was possible to improve on the original design.

What would be the best option to get a 760 portable again? Recelling a Li-Ion?

I think the NiMH is easier to rebuild, though to be honest I haven't seen one in over a decade.
IIRC the Li-ion battery doesn't use 18650 cells, but something a bit smaller, maybe 17500?

[TinkerMan]

IIRC the Li-ion battery doesn't use 18650 cells, but something a bit smaller, maybe 17500?

of which thinkpad battery are you talking about?

does anyone have a list of type of cells each thinkpad battery have? like the X230/X220 batteries have different sizes, there is slim 6 cell pack and a thick 6 cell pack, so presumably these are different cell sizes
thanks in advance

[axur-delmeria]

IIRC the Li-ion battery doesn't use 18650 cells, but something a bit smaller, maybe 17500?

of which thinkpad battery are you talking about?

does anyone have a list of type of cells each thinkpad battery have? like the X230/X220 batteries have different sizes, there is slim 6 cell pack and a thick 6 cell pack, so presumably these are different cell sizes
thanks in advance

For the 17500, I was referring to the ancient Thinkpad 760. The X220 and X230 use 18650's save for the slim 4-cell which uses a prismatic (rectangular) cell, but I don't know the size/model.

[Radioguy]

I think the NiMH is easier to rebuild, though to be honest I haven't seen one in over a decade.
IIRC the Li-ion battery doesn't use 18650 cells, but something a bit smaller, maybe 17500?

Hmm. Which would have more longevity, though? The NiMh or Li-Ion? I can't remember for the life of me which performed better, and which died first (although I think I do have one or more of each, albeit deceased)

[axur-delmeria]

Hmm. Which would have more longevity, though? The NiMh or Li-Ion? I can't remember for the life of me which performed better, and which died first (although I think I do have one or more of each, albeit deceased)

In terms of battery run-time, Li-Ion would probably win. However, with the primitive battery management circuits in those ancient battery packs, I worry about their performance and health in the long term.

There's an old webpage featuring the 760XD archived in the Internet Wayback Machine. It includes a teardown of the battery pack, among other things. I'll try to see if I can find it.

EDIT Found it! : https://web.archive.org/web/20070810000 ... 760xd.html

[evening_hunger]

Just re-celled the 6-cell battery in my T30. Actually, I bought an off-brand replacement, which held charge but wouldn't charge from the laptop. Seeing this would be useless, I contacted the seller but they haven't responded soon enough, and I had decided to move all the cells (welded with strips) from the new pack to the old, IBM-made pack. After close examination, I carefully moved the new cell ensemble to the old IBM battery pack and resoldered at the terminals in a way that 1:1 matches the old pack.

Result: it works sorta: the machine works off the battery and it can charge it. However, it is clear that the chip controller has not reset to the new cells. It still shows that I have 4% of the design capacity (which was the state of the old cell ensemble). It would be good to have some way to reset the controller, but I have no idea how to do that. I've heard there are some battery gauges one can control from Windows, but I run Linux and Windows would be hard to get.