Heavy Duty Alternator - Can I overcharge the system?

[Bubsco]

I have a 69, 350 with dual batteries. Came that way when I bought it. I am upgrading the system and adding an isolator, inverter to run goodies, and new battery cables. One standard battery and one deep cycle for the goodies. I think I need to add a heavy duty alternator as well.

My question is do I have to worry about over doing it. I assume (and you know what happens when you assume!) that the internal regulator in the alternator will make sure of proper output. Do I have to worry about old wiring? Can I overcharge the system? If I upgrade, what size (80, 105, 140 amp) etc? Any manufacturer preferences?

Thanks as always for all the expertise in the forum.

[da-burb]

I know my battery isolator has a note on it to not exceede 70 amps. I don't know if they make them with higher ratings.

[jeffnstef]

on a site about boats (Donzi)
Most cars have one battery but a bunch of boats have two and there is some good info here

donzi link

[Mel Foye]

Ah yes, Bass Pro Road and Big Bucks Steak House. An alternator will only put out what is needed and then only up to its limit. Need to add up the amps you will use. Headlights, fans, heater motor, radio etc etc. Yes old wiring can be a concern but remember the individual circuit will only see what is on that specific circuit. So an amp gauge will see all amps but the wipers only the amps needed by the wiper motor. Mel

[Florida Mike]

Think about it before you buy that deep cycle battery.....most only have a one year warranty and cost more than regular car battery. I say buy a car battery...if it dies in a year they'll prorate the life you didnt get.jest my 2 cents.
mike

[Americanrider]

You had ought to read all of this before you mis-match dual batteries...

http://67-72chevytrucks.com/vboard/s...t=dual+battery

I just picked up a 250 amp isolator kit from painless wiring, they make other sizes also.

[Florida Mike]

Lots of great info in the link above!
mike