Testing UPS batteries

[MaXJohnson]

Anyone have some tips on testing lead-acid batteries in a UPS. I have an Alpha Technologies UPS-1000 with some small 12v batteries in the main inverter/charger and an auxillary box with 3 full size 12v batteries in series for 48+ vdc supply. With the cables still attached and the unit running, I have taken a voltage reading across each of the 12v batteries looking for approx. 13.5 volts. One of the batteries was close to this, one was down around 12.1 volts and the other was up in the 15+ range. This would indicate to me that the 12.1 vdc battery should be replaced.

Is this a valid test, or do I have to shut down the UPS, and/or disconnect the cabling between batteries to get a valid reading?

TIA

 

[Sennback]

This could very well be a valid test.

The voltage should be the same on all batteries if they are connected in the same way.
If any of the batteries are different in voltage it should be changed.

Another rule could be:
non serviceable batteries should be replaced after 5 years.(gel batteries)

Serviceable water batteries should be replaced after 10 years.

A load test on the batteries are the best you can do, but isnt always necessary. So I think what you have done is good. That is how we are doing it in "the field" today.