My alternator on my campervan appears to be struggling:
The voltage at the starter battery appears low, with the engine running is around 13.8v, but after driving a short while I can see the voltage starts dropping towards 13v. Engine stopped the starter is around 12.8v I think.
Could a poorly starter battery drag down the 14.4v from the alternator or should this stay roughly the same at the terminals regardless. And I should expect the alternator voltage to remain roughly the same when headlights and other loads are turned on? If the voltage at the starter battery drops as loads are applied, whilst the engine is running, is this a sure sign that the alternator is poorly?
The van is starting OK and from the readings the alternator appears to be having a half-hearted go at charging things, but the voltage is no longer high enough to activate my voltage sensing split charge system and so my leisure batteries are only charging intermittently.
Once its stopped raining I'm going out for another spanner session...but is there any way to test the alternator properly?
460 mile round trip to Twentyfour12 on Friday so I need to accurately diagnose the problem and fix it asap!
