In view of recent discussions here, as I drove my motorhome back from a
short trip today I thought it might be worth reporting the behaviour of
the batteries and chargers, so I made notes.

There are five electrical circuits.
1. The vehicle electrics (V), which are 24V. The only connection with
the other circuits is that when the engine has been running for 45
seconds Aux A is connected and is charged, and the same thing after 75
seconds for Aux B.
2. Aux A is a 24V circuit. It has a 110Ah pair of batteries and can
supply anything in the van except vehicle stuff. It is charged by the
alternator when travelling or from the mains via a 20A 'intelligent'
charger.
3. Aux B is a 24V circuit. It has a 110Ah pair of batteries and can
supply anything in the van except vehicle stuff.
4. Aux C is a 12V circuit. It has an 80Ah battery and supplies all the
12V items. Charging is from a 24/12 converter that can run from Aux A or B.
5. Mains. Powered from an inverter, or automatically from external mains
if available. Heavy loads (heaters) can only be powered from external mains.

When parked the van is normally on mains. After a few days the ammeters
and voltmeters will read roughly as follows:
V: 24.4V, -0.01A
A: 27.8V, +0.15A
B: 28.1V, +0.30A
C: 14.6V, +0.03A

Travelling from home following the above state, after five minutes running:
V: 26.4V, +5.00A
A: 26.6V, +0.00A
B: 26.3V, +0.00A
C: 14.6V, +0.03A

Travelling from two nights' non-mains camping, after five minutes running:
V: 26.4V, +3.00A
A: 26.6V, +13.00A
B: 26.3V, +18.00A
C: 14.6V, +8.00A

Travelling from two nights' non-mains camping, arriving home after an
hour's running:
V: 26.4V, +2.00A
A: 26.6V, +4.00A
B: 26.3V, +4.00A
C: 14.6V, +3.00A

Back home and on mains, after two or three minutes.
V: 25.8V, -0.01A
A: 28.2V, +13.00A
B: 28.3V, +18.00A
C: 14.6V, +8.00A

Back home and on mains, after a week.
V: 25.0V, -0.01A
A: 28.2V, +0.20A
B: 28.3V, +0.15A
C: 14.6V, +0.01A

So this shows that the vehicle is set up to charge the batteries quite
slowly, and up to a certain state of charge. This seems to me to be
normal for alternator charging. Charging from the chargers, even after a
period charging from the alternator, is faster and to a higher voltage.
What appears to be leakage from the vehicle battery is just meter error
I think.

Bill