Battery Voltage Dropping Quickly - Why ?

[Alan de Enfield]

I think that most boats are around 1000w.

One of my boats is 1000w and the other is 1200w – the important thing to remember is that if running off the batteries a 1000w will be drawing about 100A from the batteries

[mrsmelly]

7 hours ago, Alan de Enfield said:

I think that most boats are around 1000w.

One of my boats is 1000w and the other is 1200w – the important thing to remember is that if running off the batteries a 1000w will be drawing about 100A from the batteries

Speaking as a long term liveaboard I can quite categoricaly state I have NEVER left my immersion switched on when on battery power only

[Bricksh]

I suspect its also worth checking the thermostat setting for the immersion heater. After a 3.5 hour cruise I would think it should have cut the immersion heater off?