in my 66 with a 292 i always had two heavy duty batteries. i have had them hooked up parallel, i believe, without the isolator and then with a a switch to chose the battery. the reason i did was the heavy winch i had. i just had the stock 60 amp alt i think. i now have just one battery with a 100 anp alt in my 64 with the same winch. any way i have had it it would drain the battery/batteries with the engine running with much use. i think everyones ideas about just a single heavier amp alt is best. i just had to learn to pace myself, not much help huh.
