JEANNEAU 46

[STEVE1]

I have jeanneau 46 I have an electrical conundrum when I start the engines the relays that bring in different services eg nav aids .water pump .instrument lights etc.drop out.I have tested the batteries they are ok many thanks Steve

 

[A_8]

You probably have a short and to large voltage drop in the control power to the relays.

A couple of things to look for:

Oldish batteries, 4-5 yrs plus. They may still seem ok but when you draw a lot of current they may not be that willing to deliver which gives you a larger voltage drop then when new.

Oxidized connectors, check, clean and grease all electrical connection surfaces at the batteri bank and to the main relays.

You could get a voltage meter that can register max and min values, measure at or after the main relays when you start. This will confirm if there is a big voltage drop or not.
You could then check the make and type of the relays, google for the spec and compare that to your readings to confirm if its to much of a drop or not.

If there is no large voltage drop then the above is not valid and you are getting some sort of voltage spike at the poweroff curcuits for the control board, trickier to find but still possible.

Good luck!