What would be an indication of a malfunction on a GMDSS station with a 24 VDC battery system?

All of these symptoms would indicate a potential battery charger malfunction.

After testing the station on battery power, a voltmeter reading of 30 volts for a brief period followed by a steady 26 volt reading.

A constant 30 volt reading on the GMDSS console voltmeter.

After testing the station on battery power, the ammeter reading indicates a high rate of charge that then declines.

What would be an indication of a malfunction...