UPS TROUBLE

[edy252]

hi all...

i would first like to thank everyone on this board who give so many good ideas and share their experiances with everybody else.

well i want to ask you about a problem with my ups (500 VA). it's old batteries were 2 6V batteries in series to make 12V, they were keeping the computer(P4 and an old CRT monitor) up for few seconds if im lucky (power failures in my country are very common).

Now i took the ups to a guy who changed those to 1 12V battery. I got home, plugged the computer, turned it on, unplugged the ups and all was fine. But after few hours, when the power was off, so was the computer, it restarts actually not shutdown. Well i have tried to unplug the ups again today, and it worked fine.

so what's the problem?

i could buy a new bigger ups ..something like 900VA, but i wouldnt like to spend my money on something i wouldnt really need if there's another way to solve this.

thx in advance

[dconn]

I'm not recommending this and I don't want to burn your house down, etc but what I've done here is taken a small APC UPS (800VA 640watt I think) and, because its sealed battery was dead, ran cable (the UPS looked like it used 16 square) to 2 X 300AH 6V Lead Acid batteries (the UPS used a 12V 7.2AH battery).  I guess that I'm never perfectly charging the lead acid batteries because I think sealed battery chargers never carry out equalising charges so I might be killing the batteries - but its a great UPS - it will keep a couple of computers up all day on its own if necessary.

Derek

[richhagen]

I did the same thing on a camera recording system, tied in a larger battery in place of the 7AH sealed batteries.  Seemed to work fine.  I then tied off the 12 volts for the camera power.  The charger in the UPS couldn't keep up and indicated a bad battery.  I fixed that problem by adding in another charging source, however, it isn't regulated right for the setup which causes a slight overcharging problem.  It's a flooded battery, so all I've done thus far is add more distilled water, but I think I'll have to tweak down the charging voltage a little to get a more stable setup on that one.  It shouldn't need much water because basically its on float all the time as the loads and input are both constant unless the power goes out.  Rich Hagen