[77newell]

The Prevost design of the system is such that if the batteries need charging and the coach is coasting (engine in "no fuel") then the smart electronics will ask the alternator to put out the maximum amperage it can. So, if the coach is coasting down hill (gravity pulling the coach instead of the engine) then the system will use the alternator to max out its power which provides a two-fer: it slows the coach a bit and generates "free" power. The system is designed to wait to charge the batteries as long as possible hoping for coasting to occur, so it isn't charging the batteries any time they need charging. It's making sure there is enough charge to do what needs to be done at the moment and then waiting for coasting to really charge up the batteries. Since the tolerance of AGM batteries to persistent undercharge is greater than standard batteries they use AGM. If you really wanted to juice the system you could do a design using lithium batteries and a monster alternator. Since they chose not to do that I assume the economics are not yet there. However, since we are lugging around a bunch of house batteries, it would be interesting to consider, as Bill suggested, the enlarged storage capacity we have.

One factor that probably makes multiple electric fans more efficient than a single big'un is that the electric fans require less changes in air direction in order to cover the area of the radiator, more of the air can take a straight line from the fan into the radiator. Also, the electric fans have tip shrouds that enhance efficiency.