IBM PowerPC ThinkPad - Replacing Dead Battery Cells

2002-01-02 Here's a how-to on rebuilding your dead TP:PPC battery pack! I haven't tried this yet, and we're not responsible for anything that may result from you using this document! Please report any successes/failures to me so I can update this page.

First, you need the proper replacement cells. Mike found that his battery contained Toshiba TH-1800A cells (4/5A NiMH).

"Mr.Nicad/Batteries America" ( said that HR-AUL Sanyo cells (2150 mAh) might work. Price quoted 9/11/2001 was $4.25 US$.

Here's the rest of the procedure:

Directly from Mike Nicewonger (

The process is fairly straight forward. However, you should have some experience with soldering tools and such.

Caveat: I will not be held responsible if you smoke your battery pack, burn your fingers or otherwise do something stupid.

It is important that this be done correctly. You can damage components and possible injure yourself if something goes wrong.

Tools you will need:

25W + Soldering iron (do not use a soldering gun as the tip will not hold enough heat long enough)

Solder, rosin core type

Small pliers

couple of small flat blade screwdrivers

Sharp knife

CA Glue

Masking or electrical tape


Take small knife and or screwdriver and pry open the edge of the pack where the top and bottom shells join. Do this carefully as you do not want to break the pack. You may need to do some additional scoring to the joint between the shells.

carefully remove the battery and the electronics package. remove the small PC board from the mylar pack wiring. There is a sliding latch that holds the flat connection to the PC board.

Now, you will need to remove the mylar from the battery cells. Be careful, it is very easy to damage the mylar and the traces with too much heat. You will also need to be careful removing the temperature sensor devices. Once you have removed the cells from the electronics you will need to lay out the new cells and get an idea of how you connect the cells.

Next, solder the cells together, It is best if you tin the cells before attempting to conect them to each other. Let them cool off before you solder them together as heat can damage the cells. Use some of the old connector bars if needed. Be careful to put all of the cells in the correct order. Solder the electronics to the new cells, remember to be careful to not get the plastic too hot.

test the pack in the machine, leaving the top cover off incase you need to make some corrections.

When you are sure the pack is good securely tape the top to the rest of the pack. Wick a small amount of CA glue into the seams and allow to dry. Remove the tape, then wick CA glue into the remaining open seams.

Viola! You should have a freshly rebuilt pack that will be stronger and give you years of service.

Please e-mail if you have any comments!

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