Alternator Upgrade

[Beneteau]

We have a 1997 Beneteau 321 powered with a Yanmar 3GM30F and stock alternator
I would like some input on upgrading the alternator to a high output unit Balmar or such
Suggested output--(we now run a 400AH house bank)
Any mounting issues
.All input would be helpful Thank you in advance

 

[alphadug]

I have a '98 321 with the same engine. It also has 400AH of batteries. I installed a 90 Amp Delco and Balmar smart reg. after buying the boat. The single alternator belt limits alternator output to about 90 amps max. I get a pretty steady 70 amps out of this setup at 2500 to 2800 RPM. Even with the smart reg. I never get fully caught up unless I motor for hours and hours. To avoid mounting issues I took the stock alternator to the shop that built the new one so they could match the mounts. Bolted it right in. The cost to double up the belts seems to be substantial, I was quoted close to a grand for the priveledge, decided to leave it. System works fine as is. Hope this helps.

 

[Ron20324]

There are other threads on these forums that tell us that the batteries will only accept so much juice no matter what the alt puts out.. A larger alternator will not necessarily do quicker charger. I'm sure someone will chime in with details.

 

[suttonski]

Lead acid batteries should be charged at about 15% of total capacity. A technical representative from Rolls Batteries told me that the Rolls AGM batteries, that I just bought, will accept a charge from 25% to 35% of capacity (at C20). For a 500Ah battery bank this means over 100Ah in bulk phase.

 

[Ron M]

I recently asked Westerbeke (30B engine with a 50a Mitsubishi Alternator) about upgrading to a higher output alternator. They were very non-committal. Said they had no data on engine stresses from a larger alternator, but suggested that the larger alternator will draw more power from the engine (run hotter?) and exert more torque on the alternator mounts.

 

[Maine Sail]

I recently asked Westerbeke (30B engine with a 50a Mitsubishi Alternator) about upgrading to a higher output alternator. They were very non-committal. Said they had no data on engine stresses from a larger alternator, but suggested that the larger alternator will draw more power from the engine (run hotter?) and exert more torque on the alternator mounts.

Ron,

Westerbeke, if I am not mistaken, had a 72 amp optional alt for that engine. I have installed up to 100A Balmar's on that engine without issue. Our Westerbeke 44B Four will be getting a 140A Electromaax with serpentine kit in the near future.

Our 50A Mitsubishi alt has over 3200 hours on it and is still going strong. She charges a 375Ah bank plus 75Ah reserve battery without issue.

I am only installing the 140A to test out a new product and see if I want to switch to the Electromaax product as my alternator of choice. You limiting will be your belt and for that you're limited to about 80A so a 100A alt is nearly perfect as you'll never see all 100A...

If the OP has a Yanmar the Electromaax alts and serpentine kits are the cats meow! A single four groove serp belt can handle up to 200A with less belt tension.

Phil sells the Electromaax stuff here and has excellent pricing..

Sailboat Owners.com / Electromaax