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Old 04-18-2008
hertfordnc hertfordnc is offline
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alternator wiring mystery

30 year old boat with 20 HP yanmar- some time ago the alternator was converted to a Delco - it currently has a 10SI 60 amp Delco alt used on most chevy cars in the 70's.

The field voltage had been wired directly to the starting battery- makes no sense- drains battery even with all switched off.

I wired it to a spare breaker - works great- except.....

If I select the starting battery , which happens to be a bit weak at the moment- the breaker for the alt pops a few seconds after the engine is running. The alternator still makes charging voltage even after it loses the exciter voltage.

If I start the engine from the larger bank- which happens to be fully chargerd, the breaker does not pop.

I don't know the rating of the breaker.

So, my guess is that the lower voltage from the weaker battery draws more amps for the exciter voltage and the higher draw pops the breaker.

Is that logical?

In over my head?
First Boat, a well-equipped 1977 Camper Nicholson 31
What is all this stuff and how does it work?
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