Hello Howard,

I live in Spain and also ave a long body Trooper with the 3.0 DOHC Diesel engine with automatic transmission. I got it new in August 2000 and so far I have over 33.000 miles in the meter (traveled once to the south of Morocco).

My Trooper also comes with two batteries and I also asked the dealer the reason for it and got the same answer as you got (wich is the obvious one). Anyway, I am not satisfied: two batteries is not a must for a diesel engine. A friend of mine, not with Trooper knowledge but with mechanical experience told me that, usually, when heavy duty vehicles include two batteries is because when the engine is running, both batteries are being charged but when you switch off the engine only one of the batteries supply current to whatever gadgets you have switched on (a refrigerator, lights, a computer...), so, worst case, only one battery will eventually die but you still have plenty of power from the other battery to start the engine again. This implies some sort of electronic contol to electrically disengage both batteries when the alternator is not providing charge. I do not have any electrical diagram so, some day, I have to check it. I think this is a more logical reason to include two batteries.

I hope that this helps.

Gonzalo