UPS Repair

I'm used to dealing with APC UPS (Uninterruptible Power Supplies). My main home UPS is a Belkin F6C120-UNV. It's served me well since I've had it but I have certainly taxed it's capacity battery-wise. The load usually runs about 50% or so. I don't know what made me think of it but I checked the monitor app today and noticed that the battery voltage was off, and worse, the battery level was at 0%!!! I thought it was the application, but when I felt the case it was hot. I knew something was wrong. The monitor app did not indicate the batteries needed replacing but I needed to check into this, so apart it came.

If you are familiar with APC hot-swap UPS systems you can see from this picture why this one is something of a pain to work with (comparatively).

The system board mounts above the batteries, you can see it in this image behind the UPS chassis. The batteries are enclosed in an L shaped bracket. No hot-swapping here, unless you want to die I guess.

Anyway, I removed the batteries and checked them. Sure enough, one of the them is virtually dead (running at about 4volts), the other is probably dying now too (it's at 11volts). Hopefully the charging system isn't fried from trying to juice up these batteries, I'm not electronically inclined enough to know really. I will just have to get some new batteries and find out. If it still runs blazingly hot with the new batteries (after initial charging is completed), I'm going to have to think that it's toast. Fortunately, I believe it's going to be ok, as I didn't see any fried electrical components and the fuses were not blown. (Here's real science for you) I also don't smell any of those nasty electrical burn smells that you usually get when the 'magic smoke' has been let out of electronics. I think it'll be OK....

Here's what it looks like with the batteries out of it. I am going to guess that when the batteries go out for most owners of this unit, they just toss them. Having had lots of fun over the years rebuilding printers, I'm not an electronics guru by any means, but I ain't scared to try fixing things. (Although that big transformer is kind of frightening in it's own right just looking at it!) I think I probably would have been less inclined if I had noticed any of those big capacitors sitting in there. I try to avoid things like that--and CRTs. Yeah... you will not catch me poking around in monitors. No thanks...



Update: I put new UB1280 (12V/8Ah) batteries in yesterday. Plugged it into AC and let the batteries charge up to 100%. Checked all the UPS outlets to make sure they were putting out the correct voltage and properly grounded. Then I started plugging things into it (which of course was really the most frightening part--I mean who really wants their AMD64 getting fried over a $150 power supply after all?). I ran a deep battery test and everything appears to be working just fine. Most telling is the fact (real science here again) that it's not running hot enough to cook an egg on it anymore! The case is now just a touch warmer then room temperature. 'Burn in' completed, looks like I am good to go for three or so more years...

***WARNING***
You could still get shocked & hurt or worse even with the AC power disconnected. Use whatever information you glean from this post at your own risk.


Updated 18 February 2006: Posted WARNING notice (don't get yourself killed over a $100 power supply!). Added update on the completed rebuild.