Hello, friend! Can it be that one of the traces is damaged to the point where there is still contact, yet the resistance is significant? Is the battery seated well? I would check the voltage on the other side of the board between battery contacts first.

That was my thought. Acid damaged one of the traces enough to skew the clock.

How slowly is it going out of time? It's likely just normal clock drift if other settings are properly remembered, and if the date isn't shifting.

What sort of external battery are you using?
All my computers seem to drift out of time, even back in the day I remember having to reset the time on my DOS machine.

Off topic: I keep misreading the title "System shock issue on a Chaintech 486SPM"

Thanks for the responses! I'll check the traces again but in my mind the clock would either be working or not if resistance was an issue?

I'm using a brand new coin battery, attached to the external motherboard header via a home made speaker wire / battery holder setup. I use this setup in other PC's without issue but I've used quite a long wire in this case, could that be a problem?

If it was drifting out by a few minutes a day then I wouldn't even have noticed, but it's losing a lot of time, like 8 hours in a 24 hour period. This of course isn't causing any problems, I just play games on this thing, but I'd like to fix it all the same.

RacoonRider wrote:

Off topic: I keep misreading the title "System shock issue on a Chaintech 486SPM"

I've updated the title for ya 🤣

badmojo wrote:

Thanks for the responses! I'll check the traces again but in my mind the clock would either be working or not if resistance was an issue?

I'm using a brand new coin battery, attached to the external motherboard header via a home made speaker wire / battery holder setup. I use this setup in other PC's without issue but I've used quite a long wire in this case, could that be a problem?

If it was drifting out by a few minutes a day then I wouldn't even have noticed, but it's losing a lot of time, like 8 hours in a 24 hour period. This of course isn't causing any problems, I just play games on this thing, but I'd like to fix it all the same.

The battery doesn't actually do a thing when the computer is running. Does the clock drift when the computer is on or only when it's turned off? That's a ridiculous amount of drift, might indicate a bad crystal if the RTC on the motherboard uses an external one.

Maeslin wrote:

The battery doesn't actually do a thing when the computer is running. Does the clock drift when the computer is on or only when it's turned off? That's a ridiculous amount of drift, might indicate a bad crystal if the RTC on the motherboard uses an external one.

Yeah, 8 hours is pretty dramatic. Agreed on watching what it does if the machine is left on - can you leave it powered up for 24 hours straight and observe what it does?

obobskivich wrote:

Maeslin wrote:

The battery doesn't actually do a thing when the computer is running. Does the clock drift when the computer is on or only when it's turned off? That's a ridiculous amount of drift, might indicate a bad crystal if the RTC on the motherboard uses an external one.

Yeah, 8 hours is pretty dramatic. Agreed on watching what it does if the machine is left on - can you leave it powered up for 24 hours straight and observe what it does?

OK that's a good idea, thanks guys. I'll report back.

IIRC, those external battery headers are designed for a 3.6v battery, coin cells are only 3v. May have something to do with it.

Check the datasheet for the mobo's RTC chip.

I had some boards with battery leakage that caused the traces to get high in resistance, you have to remove the coating and corrosion with sharp knife and a glass brush and put solder on it and remove again with solder wick to brush away the oxidation still there.
And then resolder the path again, some broken parts can be filled with a small wire out of a cable.
Finishing up with a coating pen to prevent contact with air or conductive parts and keep it from corroding by humidity.

Then youre probably good to go.

SquallStrife wrote:

IIRC, those external battery headers are designed for a 3.6v battery, coin cells are only 3v. May have something to do with it.

Check the datasheet for the mobo's RTC chip.

Better late than never, I can confirm that you're correct. I switched to a 3.6v battery and the clock stays set.

Thanks!