Hi Would like some info on boat batteries... I have 2 batteries & a PERKO switch [RED with BLACK HAND DIAL] It can go to OFF ONE TWO ALL My battery charger has an auto shut off so it will not over charge a battery. Over charging will destroy a battery. Just wondering when trolling for hrs. & hrs can the alt. from the outboard over charge a battery ??? Is it best when trolling to keep PERKO to ALL or is it best to switch to ONE for a few hrs then switch to Two for a few hrs? Noticed my older battery posts[main battery] were very "HOT" to the touch... I tightened wing nut [pos] as it was alittle loose... My AUX battery is newer INTERSTATE MARINE/RV & I like the idea it does not have wing nuts but rather normal nut so they can be tightened with a wrench... A little mixed bag of battery ?'s hopefully can get some light on the subject. When I put charger on old battery needle went to very low indication... I did not leave charger on though as these Hot to the touch battery post made me leary... about this battery... 2 mos ago I added quite abit of water to bring levels up [this battery is 2-3 yrs old.... other battery only 3 months old.