Nb Ceann Caslach

Thanks, that’s what I suspected and that, along with the fact hat the motor kicked when I initially switched it on, suggests that there is a fault in the controller circuit somewhere which is trying to energise the motor before the controller has even been switched on. Clearly in this state the control panel would be expected to detect a fault. ‘All’ I have to do now is find the short 😉

Neither can the control panel, I wasn’t testing the battery. I was testing the battery VOLTAGE which the control panel sees as, for the fault light to be the result of a low battery, the controller would have to see low voltage. All the controller knows is the voltage which it sees at the time. Perhaps I should have been clearer about this in my initial statement. If the control panel only ever sees ~13V how could the Fault light be because the control panel believed the battery to be low/dead? As I said, I’ll dig deeper in a couple of weeks and, as soon as I get access to the battery I will test it but I’ll also investigate why the panel is showing a fault light. It would be useful to know if the relay is supposed to energise as soon as the isolator is switched on as, if not, then that will probably be a part of the fault. I’d suspect that the relay is only supposed to energise when the motor is engaged but need to either see, or reverse engineer, a circuit diagram to confirm that unless someone on here knows the answer.

I wasn’t looking at resting voltage, I was looking for voltage drop when the relay kicked in as the only way the fault light could illuminate due to battery condition would be if it saw an excessive voltage drop, which you’d get of it had lost a cell and a heavy load was applied. Clearly if the meter sees that voltage then that’s the voltage which the controller will see and it wouldn’t then illuminate the ‘Fault’ light because the battery was low. Unless, of course, I’m missing something in its fault detection logic? Whether the relay should engage as soon as the isolator is switched on is another matter as, at that stage, I’m not sure that anything apart from the controller should be energised? I’ll dig deeper when I get back and, as a matter of course, will drop-test the battery once I get sufficient access to disconnect it and get the tester on it.

It is sitting on its own trickle charger connected to the 240V supply so I assume that 13.7 is the float voltage for that charger. I’ve never actually put a meter across it before.

I’ve checked the battery voltage and, when the relay energises it only drops from 13.7 to 13.3 so I’d suspect that it isn’t the battery. Once I get some stuff cleared off the foredeck I’ll trace the wiring and check voltages closer to the motor. It may be a bit before I update the thread again as we’re going away in the van for a couple of weeks but I’ll post findings when I do check it. Thanks to everyone for the very helpful responses so far.

Thanks for the suggestions. Battery hadn’t occurred to me but I’ll check it as soon as I get the meter out of the van.

The bow thruster worked last time I used it, we haven’t been out for a year. I switched it on this morning and when I switched the isolator on the thruster motor ‘kicked’ for a second or so and the control panel showed the Fault light. I switched it off at he isolator and back on again and the relay on the thruster clicks when the switch is switched on or off. The Fault light shows when it is on. Can anyone suggest where I should look/test with the meter? I suspect a wiring issue somewhere.