Cycling accessories / dual batteries ...

[lasitter]

I have an electric fan and water pump for my truck, and I've been considering the drain produced / fuel consumed by other accessories.

At highway speeds the movement of the vehicle thru the air is plenty for radiator cooling. The electric pump needs less than 400 watts at half power.

You don't need power steering much for straight line driving, and that could be provided by an electric pump as well.

The AIR pump could also be electric / when needed, and in this part of the country, you don't need the AC for most days.

So: What if you could have a dual battery setup and have all your accessories controlled by an electrical clutch system.

You then run the alternator long enough to charge the batteries and then shut it down, along with all the other crank driven accessories.

It seems to me that you would eliminate a very substantial drag from the engine while cruising. Given that the alternator represents a significant charging load while powered, it occurred to me that you might save more in gas by running on batteries than it would cost to recharge the batteries once they've drained to a certain point.

Alternators can produce a very significant output and therefor can charge a battery really quickly, so the alternator on-time might well be modest.

I know there are various safety considerations for operating without some accessories, but I've imagined a number of ways to automatically restart accessories if the brake is depressed or if you shift out of overdrive.

It also comes down to how many MPG the accessories account for while cruising ...