I recently replace the four batteries (12v, 7.2A/hr) in my Alpha Nexsys 900 UPS. I picked some big-name-brand batteries specifically oriented to UPS duty so I would have the "good stuff".
The four batteries are wired in series for (nominally) 48 volts. The UPS charger applies 55 volts as measured across the series string which, in theory, should be 13.75 volts across each battery and is almost exactly what the battery mfg recommends for float duty.
The problem is that two of the batteries measure 13.25 or so, one of them measures about 13.6, and the remaining measures about 14.9 volts across it.
I've rearranged the batteries in the stack but it makes no difference, they always attain about the same respective charge voltage across them.
Now, the question is, do you think or concur with my thinking there is a problem with the battery that is charging at the considerably higher voltage?
The four batteries are wired in series for (nominally) 48 volts. The UPS charger applies 55 volts as measured across the series string which, in theory, should be 13.75 volts across each battery and is almost exactly what the battery mfg recommends for float duty.
The problem is that two of the batteries measure 13.25 or so, one of them measures about 13.6, and the remaining measures about 14.9 volts across it.
I've rearranged the batteries in the stack but it makes no difference, they always attain about the same respective charge voltage across them.
Now, the question is, do you think or concur with my thinking there is a problem with the battery that is charging at the considerably higher voltage?
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