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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10 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.)

  4. Vikki McDonough says:

    I’m curious why leakage over time is such a recurrent, intractable problem for certain types of batteries. It doesn’t seem like it should be *that* hard to completely seal the battery so it doesn’t leak…

  5. Kalvin Dan says:

    Hello Michal Necasek. I have a 755CD that’s been showing some green artifacts on the display lately. I did a diagnostics test and I got the following errors:

    DEV 51, Error 10, FRU 0041.

    Is it the display or the WD graphics chip that’s causing the issue? Your help would be appreciated. Thanks!

  6. Michal Necasek says:

    FRU 41 is listed as “Video Card” in the HMM. Typically bad pixels and such are caused by the display itself, and won’t be detected by diagnostics. But it can also be bad video memory or perhaps damaged data path. If the diagnostics find a problem, there definitely is an issue. So yes, I’d say there is a problem with the WD graphics chip or surrounding circuitry.

  7. Kalvin Dan says:

    Strangely enough, I took out the 32 MB DRAM card and it actually solved the problem. Ran a diagnostics again and no errors appeared. Of course using the onboard 8 MB of ram has a performance hit. That DRAM card had issues before. I was afraid that the battery corrosion got onto the board itself. Mine suffered a minor battery leakage at the plug. Seems like it hit the DRAM card too. Otherwise everything else appears to be working. I wish there was an easy way to clean the board without damaging it.

  8. Michal Necasek says:

    If the DRAM were faulty, I’d expect the diagnostics should find that. But who knows, sometimes things are marginal and seemingly innocent differences have unexpected ripple effects.

    Trying with a different memory card might help. The DRAM cards should not be too hard to find.

  9. Kalvin Dan says:

    Sad news. Turns out, it wasn’t the DRAM module. Had to take apart the 755CD completely and now it appears there was some corrosion damage around the WD chip on the motherboard. I damaged the pins while trying to clean it. 🙁

    I’m getting another 755CD to get the donor board. Do you happen to have the link to the PDF file for the 755CD HMM? I only found the ones for the 755CS or CX. Not the 755CD. Guess I learned a valuable lesson myself.

  10. Michal Necasek says:

    Too bad, battery corrosion is really evil.

    This appears to be the official download:

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