Author Topic: Alternator setup for AGM?  (Read 93 times)

Offline Wes

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Alternator setup for AGM?
« on: November 04, 2017, 07:53:59 AM »
Folks - has anyone installed a proper alternator/regulator setup for AGM batteries, particularly on a 27 with the original Universal M12 engine?

I’d like to do this, since I’ve read that a conventional alternator (with internal regulator) will cook the AGMs. I believe I need an outboard regulator with multiple charge profiles. But the ones available from Balmar seem intended for larger alternators, around 70 amp and higher. Putting such an alternator on my little engine would require changing out the pulleys for a larger belt, and seems like it would also rob power from my none-too-ample 11 HP.


"Bella", 1988 CP 19/3 #453
Washington, North Carolina

Offline moonlight

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Re: Alternator setup for AGM?
« Reply #1 on: November 13, 2017, 09:09:42 PM »
Unless you're doing extensive cruising wherein the AGM's are getting depleted and then running a 6 hour motor cycle to recharge them; you're overthinking this.

Check alternator output voltage with fully charged batteries.  Then find a way to deplete the bank 50% to 12.4V, start the engine, and check alternator output voltage.  If you get 14.6V both times you're fine.  If you get less, no harm done unless scenario in sentence 1 is true.

If you're daysailing 90~95% of the time, your shorepower charger will handle the conditioning.  Which for the common sailor is overthinking it anyway.  AGM's, 5-7 years and they're done no matter what you do.  Same with all Lead Acid variants (in this case, the acid is just "adsorbed").

Call me off-line if you want to talk Lithium, 30-year batteries...