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CMOS Battery for ThinkPad 600X

Written on August 23, 2005

When the CMOS battery in my ThinkPad died, the machine became unusable. It would not boot because it could not remember the time. I think that this is a bad way to design a BIOS, but I don’t get to choose which BIOS I use (yet, keep your eyes peeled for OpenBIOS as it matures). I knew I needed to replace the CMOS battery, because the rest of the machine works very nicely.

What I discovered is that no one is willing to do this without at least a hundred bucks, which is idiotic. I learned from my research that the CMOS battery is encased in packaging, is difficult to remove on many ThinkPad models, and must be purchased as a specialty item via eBay or IBM. The technicians I spoke to where not able to order it until they had the laptop in their hands, because apparently there are different batteries for different 600X machines. I now believe that this is bullshit, and that they are simply too eager for my money to actually provide advice.

Rather than submit to the whims of the extortionists, I started removing screws and panels from my ThinkPad in search of the mythical battery. I found it in the RAM access hatch (I only needed to remove one screw) which is above (below?) the removable drive chassis (CDROM, DVDROM, etc.). It connects to the motherboard via two leads going into a specialty plug, and those leads connect to the battery via simple paddles. The battery and the paddles are held together by a short length of heat-shrink tubing. This sounds way more complicated than it is. The battery cover has the battery type printed on it, CR2025, which is a standard lithium battery I replaced at Blacks for $6. I detached the leads from the old battery, attached them to the new battery (being careful to replicate the polarity of the old one) with a length of electrical tape. I plugged it into the wee slot, replaced the panel, booted the machine and set the clock. It was essentially effortless, if you don’t count the visits to laptop repair shops and the subsequent anxiety.

Simple repairs can, in fact, be simple.

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