GE Fanuc 90 30

PLC lost program over the weekend a few times and we changed the battery but we were still losing the program. Ordered a new power supply and installed it with a new battery but we are still getting a red light on the battery. Any suggestions? Even tried it with some old power supplies with new batteries but same issue, red battery light is on.

when you say you replaced the battery with a new, do you mean a "new" battery from your stock that's been sitting on a shelf for 10 years? Batteries have a shelf life. Try putting a meter on your replacement battery to see if its still good

Ran into this a few times on older 90-30 systems..
Could also be...CPU, Power Supply or Backplane problem..

What CPU are you using?

Looks like it is a IC693CPU340
We have an old backplane laying around that we were going to try next. Batteries have checked out good.

is the green "OK' light staying solid green or is it out or blinking?

All green lights are solid

Since the battery is located on the power supply module and the RAM memory it maintains is on the CPU module, there needs to be a complete circuit between the battery and the CPU. Since you've already swapped out the power supply, the other possibilities are the backplane and the CPU module itself.
I have a CPU331 and a CPU363 which have a place where you can connect a battery directly to the module. I expect the CPU340 does also. Remove the front cover of the CPU module to get access to it.

We switched out the CPU and downloaded the program and everything looks good now. Thanks for the help.