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post #2 of Old 10-03-2012
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Re: HO Alternator & Serpentine Pulley Kit Install

As usual, excellent write up MS. I've got a couple questions, don' t laugh if they seem naive please.

The new alt can put out 140 amps a hour, the bank is 500ah. Assuming you were involved in sizing the bank the owner is educated enough to have sized it so he doesn't cycle it below 50% (250ah).
In the first hour the alt dumps in 140ah, bank is at 390ah / 78% - we'll call that 80% because it's close enough.
At that point - 1 hour and a couple seconds - it's no longer in bulk charge mode (I'm ignoring the efficiency ratings and drops amps) and has gone to absorption mode.

Isn't the 140 amp output kind of overkill? It saves some diesel running time certainly, but is it worth the presumed 2k of cost?
If he's got 100ah of solar capability this makes sense - run the motor a hour in the morning while it's still in bulk acceptance, then absorption rate with the solar to get almost full by sun down.
I ask because I'm going to have similar needs on my boat (500 ah bank, 200ah 'daily diet).

Also - what's the take off the engine/shaft horse power, I'm assuming there is no free lunch.

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