Motherboards made from the late-1990s to today generally have a CR2032 cell to maintain the system realtime clock and CMOS settings when the machine i

Rubenerd: Building a replacement 386/486 CMOS battery

submited by

Style Pass

2024-12-23 15:00:06

Motherboards made from the late-1990s to today generally have a CR2032 cell to maintain the system realtime clock and CMOS settings when the machine isn’t operating. When these wear out, you can pop them out with a flathead screwdriver, and replace them with a new coin cell without much fuss.

Prior to this, a soldered NiCD or NiMH barrel battery was the most common RTC battery in PC compatibles, of which Varta made the majority. These recharged from the board, which was convenient when these boards were new and in regular use. Unfortunately, time has proven a harsh mistress, with most of them becoming prone to leaking and damaging boards with corrosive electrolyte. The Bad Idea Barta Board is a tongue-in-cheek reference to their destructive power.

I’m lucky that my Am386 motherboard either didn’t ship with a Varta barrel of death, or it was removed long before it came into my possession in the early 2000s. My new 486 motherboard shipped with a corroded barrel, though fortunately the damage was minimal and cosmetic. Not all my boards have been this lucky.