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beetle · 17-12-2010, 12:02

Quote:

Originally Posted by delmarrey

Normally one does not want to take a battery below 75% anyway making a 100 A alt. fairly useless on a boat with only 2-3 standard automotive batteries. That's why I stated way early, and referring to a different thread "Unless you have a large battery bank (e.g. 1000 Ah) it would be over kill."

I'd take exception to the point above -

it's normal to run a deep cycle lead acid battery down to 50% discharge, then recharge battery to 80-85% of capacity; this keeps the charge rate at it's maximum efficiency (e.g., most power accepted by the battery per unit time). It's also normal to couple a hi-output alternator with an external regulator that is observing battery state (temperature, voltage).

I have used an Ample Power 105AH 12vDC hot-rated alternator controlled by Ample's external regulator, since 1994. I typically see that alternator kicking out 85-90 amps for 90 minutes at a time while recharging a 450AH battery bank (4 x 6v deep cycle golf cart batteries) when passage making I try to charge twice a day, once in the morning and once in the evening.

And yes, that alternator is in the engine room, along with the engine, and it does get hot

- rob/beetle