Small AGM question.

[Daniel Armstrong]

I have a 17/20AH battery that I had connected to an APC Back-UPS Pro 650VA
(stock battery is 11AH) and one day I had the UPS do a battery self test and
it indicated a bad battery so I replaced it with another of the same
capacity out of my Xantrex Xpower 300C. I tested the bad one and determined
that it had developed a bad cell. The symptoms are that cell 2 gets hot and
gasses (rotten egg smell) whenever a load is connected.
- +
123456

How often do AGM batteries develop a bad cell in constant 13.8 float and
what type of fault is it likely to be? I know the charge controller in the
UPS is OK because when I got it used and replaced the bad stock battery that
was in it (died due to sulphating) I left my multimeter connected for a week
and it stayed rock solid at 13.8 the entire time.

 

[Pooh Bear]

I have read that AGM battery banks have a much higher maintenance cost, in
terms of average time diagnosing cell problems, compared to flooded
batteries (presumably of equal quality). I don't claim to completely
understand the statement, as flooded batteries require a lot of routine
maintenance: watering, equalizing, and, perhaps, cleaning the connections.

Are you sure the APC isn't designed for gel cells? I think the float values
are a little different.

Given that they use the same chemistry ? surely not ?

Graham