Don’t Let This Happen to You

I recently got an old ThinkPad on eBay for a modest price. The seller marked it as defective, with absolutely no warranty. Since the ThinkPad came with a port replicator (the kind with two PCMICA slots) and an external 2.88MB floppy drive, I figured that even if the laptop is completely dead, the accessories are worth it (those 2.88MB drives aren’t easy to find!). The laptop itself seemed in decent enough shape, at least from the outside.

When the laptop arrived and I looked inside, it was obvious what’s wrong with it:

Corroded EMI shield

There had clearly been a nasty leak. Probably both the main battery as well as the small standby battery (both Ni-MH) had some leakage. Based on the location, it seemed like the standby battery caused most of the damage.

Some of the electrolyte(?) crystallized on the inside of the laptop case:

Battery juice crystals Battery juice in crystalline formThe CD-ROM drive was especially badly hit as the standby battery is located just underneath.

CD drive corrosion

The laptop had probably not been used in about 10 years. It’s not entirely clear if the electrolyte flowed through the system or if it first leaked out to the bottom and then spread through evaporation.

And the best part? After some cleaning, the ThinkPad works again! Despite the corrosion of the metal parts, the electronics don’t appear to be damaged. IBM did build those laptops well.

Moral of the Story

Don’t leave NiMH (let alone alkaline!) batteries in devices you don’t use. They can damage the device. And if anyone tells you NiMH batteries don’t leak, they’re lying.

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3 Responses to Don’t Let This Happen to You

  1. OsFn says:

    Not strictly relevant, but a lot of old Win/DOS/OS2 documentation (Microsoft Programmer’s Library 1.3) is found at Vetusware at:


    os2getst MS OS/2 Getting Started
    os2lrn MS OS/2 Learning Guide
    os2usr MS OS/2 User’s Guide
    os2dskrf MS OS/2 Desktop Reference
    prgmr1 MS OS/2 Programmer’s Reference Vol. 1
    prgmr2 MS OS/2 Programmer’s Reference Vol. 2
    prgmr3 MS OS/2 Programmer’s Reference Vol. 3
    prgmr4 MS OS/2 Programmer’s Reference Vol. 4
    os2dev MS OS/2 Device Driver Reference
    os2insd Inside OS/2
    os2pm Programming The OS/2 Presentation Manager
    os2adv Advanced OS/2 Programming
    os2smpl OS/2 Sample Code
    os2kno MS KnowledgeBase – OS/2

  2. Michal Necasek says:

    I’ve had the ISO for several years, and have most of the manuals in printed form… but it’s a very interesting collection and especially the old OS/2-related MS Knowledgebase articles are very hard to find elsewhere.

  3. Armin says:

    Thanks a lot for this information! I have a Thinkpad 755CD around here for years and I just wanted to gain some Information – found your site and just opened the PC to find a battery just beginning to leak. You saved my treasure!

    (After removing batteries from several Amigas from the same era, I really didn’t think of that one.)

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