Switching to Battery after shutting down

[Anonymous user]

After shutting down my computer, the Back-UPS appears to switch to battery and that the internal fan is running. This started before I pushed the on/off button on the front and continued after everything was completely powered down. After turning my computer back on (about 18 hours later), I noticed that the Back-UPS was warm. Curious, I checked with PowerChute and found that only 84% power remained (I had noted that it was fully charged when I shutdown).

Why would it switch to battery with no load? Wouldn't this shorten the battery life as well?

If it helps any it's a Back-UPS XS 900, I'm running PowerChute Personal Edition 2.0 on a Windows XP Pro computer. I also have a Back-UPS XS 1300LCD on a Dell Inspiron 531 with Vista Home Premium, running PowerChute Personal Edition 2.2 operating with no problems.

[BillP · Accepted solution]

well to begin, the fan should run anytime the UPS is on battery.

i am confused on what happened. you turned the computer off, but left the UPS on. right after you turned the computer off, the UPS went to battery for a little bit until you turned it off via the front switch.

it doesnt make sense to me either. the UPS should only go to battery (no matter what load is attached to it) when: there is a black out, undervoltage, overvoltage, electrical noise/THD, or the frequency is out of range.

i would have had to assume one of those conditions occured but i am leanings towards the issue that you dont think one of them did. also, anytime the UPS is plugged into the wall, it should be charging anyway (doesnt matter if the UPS is switched on or off).

can you clarify on the items i mentioned above so we can see if we can figure out what happened?