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386SX on board CMOS Battery Fix


Experienced Member
Jun 27, 2011
Newnan, GA USA
Like many 386SX motherboards, mine had a CMOS 3v coin battery soldered on the motherboard. Well, it died like they all do and I got tired resetting the date & CMOS info. Since replacement battiers are non-existant for this MOBO and my normal 2032 Coin holder would not fit, I decided to just wire in an external battey. I unsoldered the dead battery and soldered in about 12" of black & red wire to the + and - connections. I got a dual AAA battery holder from Radio Shack and soldered it to the wire keeping the correct polarity (I used shrink wrap to prevent shorts). Using a bit of double stick tape I attached it to the bottom of the mini-tower case. I bought a pair of lithium AAA batteries and bang!, no more CMOS issues.

If the batteries ever leak they are away from the motherboard and won't cause any damage.

About 15 minutes of work.