I have returned from an enforced absence, (not at HM pleasure, honest) and have now let the domestic bank discharge a bit.
Situation is as follows:
Batts left off shoreline charge for 3 days. Reading 12.9v. Discharged to 12.6v.
Engine run @ 1600rpm
Alternator readings
14.4v; 4 amp on +ve lead, 0.2 amp on -ve lead.
Bank readings
14.4v, 1.8 amp on +ve, 1.0 amp in -ve.
After six hours cruising:
Engine rpm 1000
Alternator readings
15.2v
0.5 amp +ve, 0.2 amp -ve
Bank readings
15.2v
0.8 amp +ve, 0.25 amp -ve.
I suspect that this may be a problem with something in the alternator, not picked up on the automotive bench test last October.
Any other thoughts please?