naturist wrote:
Those are signs of a battery that is being overcharged and/or is drying out. #1 step is to check that the water level is up where it is supposed to be. #2 step is to find out what voltage the charger is laying on it, both as the engine is running and as the shore power is plugged in and the engine is off. You will need a voltmeter for that.
It is possible that the battery itself is shot. It is also possible that the charger(s) are bad. A voltmeter will tell you which it is.
I had already added distilled water. Just checked on shore power:
Leisure batteries getting 13.5V (pair of T125's)
Chassis battery getting 13.5V and fizzing still (so again turned off the blade switch afterwards).