Electrical system Beneteau 393

[tomtom393]

I will try and keep this short - I am having some problems with the Amp Meter that we have located on the boats electrical switchboard.
I believe from memory that it reads -75 to +75 - when we start the engine and run it for a few minutes with lets say the navigational aids running it shows + 10 amps which I reckon to be rights given the draw of power versus the alternator work of charging the batteries. Now here is the strange part; every so often the Amp meter will jump to +75 amps and stay glued to the end stop for 5 minutes or so and then return to normal - is this normal??
I have a three battery set up 1x starter (new) 2 x Domestic (new) they are rated at 115 Amp hours and are specfic to the job in hand -

The yacht electrical system is beyond my knowledge but I believe that we have a battery management system and a separate show power charger for when we are connected to 220Volts... At present I think we have a problem with the charger for shore power but not sure they are linked.
Can someone give me some pointers!!!
Thanks

 

[halcyon]

Check voltages at batteries, and across the shunt for ammeter with engine running.

You are looking for voltages when charging at 10 amp, and what voltages you have when charging at 75 amp plus.

This will indicate if alternator voltage rises, or that current across shunt is increasing correctly, it could be a backfeed of voltage to shunt that is giving a false reading.

But collect evidence first.

Best of luck.

Brian

 

[tomtom393]

Thanks for the quick reply - I am sure that it is something to do with wiring all my navigational gear through the same + and -
When I installed my Navtex and AIS I used the GPS negative and positive to power all three pieces of equipment and ever since these problems have arisen... will give it a go next weekend
Thanks