T&T: Alternators

[David&Joan]

John:

I think you will be fine with a 94-165 Balmar driven by your 1" flat belt. 
In actual practice you will be charging at much less than 125 amps on 
average. Just set your Balmar alternator to charge at 125 amps maximum. The 
165 amp alternator will run cooler and last longer.

If you want to go to the expense of setting up for a second alternator, that 
will work even better. I like the setup you describe, with the original 
alternator charging the starting battery and the big altenator charging the 
house bank. Keep a set of jumper cables on board if one alternator fails. 
Don't bother upgrading the original alternator, it will work fine to keep 
the starting battery topped up.

David
----- Original Message ----- 
From: "John Leroy" <johnl2003@earthlink.net>
To: "Trawlers and Trawlering List Post" 
<trawlers-and-trawlering@lists.samurai.com>
Sent: Wednesday, December 06, 2006 8:33 AM
Subject: T&T: Alternators


> Thanks to all who have responded to my previous posts. I have
> received a lot of invaluable information.
>
> My project is a Monk 36 with a Cummins 220 that currently has the
> original 63 amp Bosch K-1 alternator driven with a non toothed
> serpentine belt.
>
> I'm planning on adding a Mastervolt Mass Combi 2kw inverter with the
> Masterlink MICC remote control panel. Does anyone have any opinion
> of this unit as compared to the Prosine?
>
> I'm planning on two 8D batteries in parallel for the house bank.
>
> While the rated amp hours of the two 8Ds would be 250  amp hours
> each, the 20 hour amp-hour rating would be only 220 amp hours.
> Assuming an acceptance rate of 25% of that, each battery could accept
> about 55 amps, for a total of 110 amps for the two batteries.
>
> If I am cruising at 1400 rpm, with a pulley ratio of 2:1, the
> alternator would be turning at 1800 rpm. It looks like the Ballmar
> 94-165 puts out about 125 amps which would work.
>
> I talked to Cummins and it looks like the max we could put on to
> replace the 63 amp Bosch K-1  alternator would be the 100 amp Ballmar
> 94-100  alternator which  would produce maybe 75  amps at that rpm,
> which is not enough.
>
> I thought of adding a 100 amp alternator, but I believe the existing
> alternator is internally regulated and it would not do to mix that
> with the new externally regulated alternator.
>
> It might be possible to modify the existing alternator by opening it
> up and cutting the internal excitation lead, and adding an external
> one, but probably the better course of action would be to change out
> the existing 63 amp for a 100 externally regulated alternator and add
> an identical 100 amp externally regulated alternator with an
> additional pulley. I think there are regulators built to control two
> alternators.
>
> It would be nice if someone had stock brackets to install the new
> alternator.
>
> Then the outputs of the two alternators and the inverter could be led
> to the house bank with combiners to the start battery and perhaps the
> genset start battery.
>
> Another route would be to retain the stock alternator and route it to
> the engine start battery only, and not combine it with the house
> bank, and add a 165 with two belts and new bracket for the house
> bank. A switch could then be used to use the house bank for start in
> the event the start battery got flattened.
>
> Does anyone have any comments? I would think someone has had a
> similar project, and I'd like to not re-invent the wheel if possible :).
>
> Regards to all,
> John LeRoy
> Pensacola, FL
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