Electrical problems

[Cavalierbond]

Started losing the lights , nothing else .. both engines start ok of both batteries ..
now stern thruster “ clicks “ and that wired directly into the battery
Help

 

[superheat6k]

What are your battery voltages ?

Under load and disconnected one to the other.

Are you using a 0-1-both-2 switch ?

Is the thruster on a separate battery ?

 

[Cavalierbond]

Stern Thruster( sliepner ) is direct wired to one of the batteries
I have two batteries.. one does a engine and the other does a engine and the house circuits

 

[superheat6k]

I had a similar issue - my Port engine battery was knackered.

 

[Cavalierbond]

Thanks … even tho it started the engine ok ???

 

[superheat6k]

Thanks … even tho it started the engine ok ???

On my boat the electrics are overly complex, with direct feeds from each battery bank to each engine, via isolation switches, plus there is a separate Off - 1 - Both - 2 switch which supplies the rest of the boat. So when this is at 'Both' the stbd bank back feeds the port starter and vice versa, albeit via a hidden 80a MCB from each bank (I now know where these bloody things are !), so with the port knackered it would start on the stbd back feeding as the engines start very easily so the MCB would not trip on the typical start (which is good), but when I ran the stern thruster for more than a few seconds the hidden MCB would trip resulting in no port engine start, nor stern thruster, nor engine stop solenoid.

This did cause me some head scratching because the hidden MCBs were also absent on the drawings.

The terminal voltage of the dead battery at no load was good, just would not put out any power when required beyond a few amps.

 

[PaulRainbow]

On my boat the electrics are overly complex, with direct feeds from each battery bank to each engine, via isolation switches, plus there is a separate Off - 1 - Both - 2 switch which supplies the rest of the boat. So when this is at 'Both' the stbd bank back feeds the port starter and vice versa, albeit via a hidden 80a MCB from each bank (I now know where these bloody things are !), so with the port knackered it would start on the stbd back feeding as the engines start very easily so the MCB would not trip on the typical start (which is good), but when I ran the stern thruster for more than a few seconds the hidden MCB would trip resulting in no port engine start, nor stern thruster, nor engine stop solenoid.

This did cause me some head scratching because the hidden MCBs were also absent on the drawings.

The terminal voltage of the dead battery at no load was good, just would not put out any power when required beyond a few amps.

Easy for the OP to rule this out, disconnect the negative on the "good" battery/s.

If the engine still starts it isn't the battery. Check all of the connections (remove, clean, refit). In particular, the negatives, usually the culprit that gets overlooked.