Multiple electrical issues

[sighmoon]

This is my third season with the boat, and until this year, there've been no electrical issues. This year though, we've had a spate of them:

Domestic water pump (turned out to be a fuse)
Domestic water heater (yet to investigate)
Batteries over charging - the charger is supposed to cut out once the batteries are charged. At least one battery is totally knackered.

Is there any conceivable common cause (i.e. might the dead battery be shorting out the charger, and consequently sending more than 12V through the electrical system?), or are we just unlucky?

 

[savageseadog]

It might be the negative battery connection to the engine/starter and everything else, look for corrosion, bad terminals etc.. It needs to be 35mmsq or larger and the wiring to the fuse panel at least 6mmsq, preferably 10.

 

[Stemar]

I can't imagine any way a faulty 12v battery could produce more than 12v, so I don't think the battery could be the cause. However, blown fuses and knackered batteries could be caused by to many volts flying around, so I'd be inclined to suspect the battery charger. My first step would be to measure the voltage it's pushing out.

 

[halcyon]

This is my third season with the boat, and until this year, there've been no electrical issues. This year though, we've had a spate of them:

Domestic water pump (turned out to be a fuse)
Domestic water heater (yet to investigate)
Batteries over charging - the charger is supposed to cut out once the batteries are charged. At least one battery is totally knackered.

Is there any conceivable common cause (i.e. might the dead battery be shorting out the charger, and consequently sending more than 12V through the electrical system?), or are we just unlucky?

Is the water fuse the right size ?

Depends on battery charger, but modern ones can charge to 14.6 volt before they switch to a lower voltage, but old and / or shot batteries may fail to reach this voltage, the result is gassing, boiled dry battery.

You can only decide if you measure the voltages and check what is happening.

Brian