Question About Backup UPS Charging Voltage

vulcanman

Senior member
Apr 11, 2001
614
0
0
So, I have two identical UPS units. Both are TrippLite Backup Office 350VA. They both quit providing backup power ... around the same time (about 6 months ago). All outlets worked but the battery never kicked in (the red low battery indicator flashes).

Having verified the battery type - CP1245 ... I purchased two replacement batteries. But that did not help. The red battery indicator is still flashing.

I put a voltmeter across the battery terminals. It reads around 10.5 Volts for both batteries.

I check the voltage across the pins that connect to the battery terminals (without the battery) ... and it read around 3 Volts. How come !

Can someone tell what the charging voltage would be. The 3V sounds kinda low. Its a 12 V battery.

Thanks !!
 

MWink

Diamond Member
Oct 9, 1999
3,642
1
76
I do think it's odd that both would stop working around the same time. On the other hand, I've had nothing but bad experiences with Tripp-Lite UPS's (including an experience similar to yours but with only one unit). 10.5V is not acceptable and either indicates an almost totally drained battery or one with a shorted/faulty cell.

The UPS should be charging the battery to about 13.6V. If you have some sort of 12V charger you could try using it to charge the battery for a few minutes. It should come up to at least 12V fairly quickly unless it has a faulty cell.

There are some UPS's that won't try to charge a battery that is too low but even 10.5V is high enough I would expect it to work. I guess it's possible you bought 2 bad batteries but you could rule that out if charge them as I suggested and their voltage comes up where it should be. Otherwise it sounds like you have a couple bad UPS's.