On Sun, 8 Feb 2009 03:17:57 -0600, "RogerN" wrote:

I've been thinking about mounting an automotive alternator on a small
gasoline engine to make a portable battery charger with respectable output.
The purpose would be to charge auto batteries when there are no outlets
around. Of course you could do the same thing with a generator and battery
charger but I think you can get perhaps 70 amps or more from an alternator.

Yes, typical alternators for passenger cars range from 50A, maybe even
less for the smallest cars, up to 70-80A, maybe as high as 100A.
Larger than that, and they'll most likely be 24V.

Note that some car manufacturers equip their cars with different
alternator sizes depending on which part of the world they will be
sold in. If you're looking for a big one, look for cars imported from
a cold part of the world.

Remember that an automotive alternator can be damaged if it is run
without a battery connected.

Also could be
useful for camping and boating, could recharge the trolling motor battery on
the lake, etc...

Check the specs for those types of batteries. They may not be able to
handle as high a charge current as a starter battery.
--
RoRo