Hope you guys can help, because this problem is killing me.
I've had some 12v
gremlins on the coach since last Summer. We had the first big camping trip this weekend and had further 12V
issues. There appears to be 12v
leakage across the auto and coach systems. Specifically, there is a fault which can be replicated which I assume relates to a 12v thermal breaker.
Position is as follows:
Starter and Leisure batteries both fully charged, with good voltage readings and terminals cleaned/tight connections (I have triple checked this);
I replaced the Isolator last year with a like for like replacement, so that should be fine;
Starter solenoid does not appear to be functioning correctly, but is yet to be replaced;
We were boon docking this weekend and working mostly gas with the only real electrical drain coming from the Dometic fridge controller (fridge running on gas);
Internal 12v systems work fine and voltage on 12 V distribution board matches the leisure battery (12.68v);
If you then run additional circuits concurrently e.g. cigarette lighter to charge an iPhone, the interior lights or fan - the fridge 12v supply cuts out - no lights on the fridge.
I then went to check the voltages again - results as follows;
These tests were all done with the Auto battery disconnected (so not to confuse the position).
Voltage on 12V distribution board is now only 4v (was 12.68v);
Voltage across leisure batteries is still a healthy 12.68v;
Voltage on rear of kill switch (which feeds 12 v board is only 4v)
Voltage on battery side of kill switch is only 4v;
Voltage on either side of thermal breaker on rear of battery box is only 4v;
Voltage on lesiure battery side of solenoid is only 4v;
HERE IS THE REALLY WEIRD BIT, the voltage on the end of the heavy red cable coming directly from the leisure batteries is only 4V - SEEMS IMPOSSIBLE BECAUSE THE VOLTAGE ON THE BATTERY TERMINAL READS 12.68v;
After a while (and I am assuming this is where a thermal breaker is somehow involved) all comes back to normal where fridge works, voltage on 12v distribution panel all matches the batteries (12.68v).
I then did some further tests. The 12v kill switch does kill voltage to the 12V distribution board, so that is all working fine.
I then reconnected the starter battery with the kill switch off, but the fridge still worked as did other interior 12v services, which suggests that the auto and coach batteries are connected in some way (I am assuming via faulty solenoid or someone splicing together a circuit).
Can any one advise on where i might start with fault finding on this one?
Thanks in advance for any thoughts on how to move this one forward.
PS I have got a Sure Power: 12V 200A Battery Separator to replace the stock solenoid on the back of the battery tray, so will try and fix that over the weekend. Sure Power 12V Bi-Directional Battery Separator (200 Amp) - Part#: 1315-200