Balmar alternator

[Kevin]

1. Hello,
   I had my starboard alternator go out on me. I have a 2001 3500 Tiara Open with twin 370 6BTA engine­s. I have 3 AGM 1000 MCA 800 CCA house batteries on the star­board side. The star­board alternator is missing it’s tag. The tag is still on the port alternator Ba­lmar (912-100) 100 amp and it’s charging two AGM starting ba­tteries . I have a external alternator voltage regulator. Sh­ould they both the star and port be the exact same alternato­rs? Both 100 amp? Is your alternator a exact fit. Should I buy the 105 amp or the higher amp option? Thanks

Topic

[Chuck Rich]

2001 TIARA 3500

I have the same boat and engines the alternators are the same, you also have the charles regulator that has another control box behind the seat right below the electric control panel in your cabin, there’s 4 or 6 screws to take the panel of then you can check or change the charger to charge either acid, agm or gel batteries separate setting for each. I have the west marine gels in mine there nine years old last Feb. and going great.

[Thomas]

Why don’t you just rebuild the alternator, maybe $150, and reinstall. I did one of mine and it works perfectly with one year warranty and you don’t have to change anything. New bearings, windings, brushes etc. Guy told me it was still in good shape except the windings must have been shorted or something. 

[Tony Athens]

Kevin,

 

Listen to David as he’s into this type of stuff and has the field experience to back it up..  But I will add this to the mix to ponder..  

What an alternator is “max rated” at has nothing to do what it actually puts out as all of them  are very “alternator shaft RPM sensitive”,  especially at lower engine RPM’s like when you first start up and then running slow trying to get then engine up to temp.. This is when you need the “amps most” and a typical 100-130 Amp  alternator will be at well under 50% of it’s rated output if the engine RPM is under 1400… ..

AS to all the rest, both  Leece Neville & Delco  make 1st class  “off the shelf”  units that are “plug & play” units up to 140 amps or so and all are in the $400 range or less, with a pulley………..IMO, you do not need a remote regulator in 90% of the cases, but with that said, any competent alternator shop can modify any of these units to work with a remote regulator if that is your bag…. Personally, I prefer “simple”,  and like to monitor “battery terminal voltage”   so I really know what is going on.. Anything else is a guess at best..

 

Just my 2-cents..

 

Tony

 

 

[David Marchand]

Kevin:

A few observations:

An AGM battery with a CCA rating of 800 probably has an amp hour rating of 80. You have three in your house bank so the total amp hour capacity is about 240. A rule of thumb is that you shouldn’t charge batteries at more than 25% of their amp hour capacity although some say that you can up that to 50% for AGMs.  So that means that one alternator putting out 100 amps is almost all that you can charge with effectively.

From your description one alternator is charging the house bank and the other is charging the starting batteries- two, presumably one for each engine. I wouldn’t worry about meeting the rule of thumb for the starting bank because they usually don’t need much charging.

It is fine to have two different alternators, particularly if they are split between the house and starting batteries.

And you don’t have to buy an expensive Balmar alternator. Leece Neville makes high output alternators that fit the Cummins mount and have terminals for external voltage regulators. But the standard Delco 22si that came with those engines will also work fine to charge the starting batteries, although it won’t work with an external regulator.

David

[Author]

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