toyota/split charge electrical problem

[jamieT]

To all gurus of the black art of electrics,
Our only casualty from the Marsabit Moyale road seems to be an odd problem with our battery system.

After a long run the car will not start and one of the starter batteries seems dead. The next morning it starts fine. What am I missing.

Might be connected to our system. Normal 2 batteries plus aux on split charge system.

Still I cannot get over the mystery of no power to start the engine (just the click) in the evening and yet turns over first time the next morning, what am I missing?

Thanks in advance.

JT