Join Date: Jan 2003
Location: Maine Coast
Thanked 126 Times in 94 Posts
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Re: Help! Weird Alternator Problem
Originally Posted by GrahamO
This has been an issue since I bought the boat and three yards have expensively failed to fix it. I have a Yanmar JH series engine with a large AMP alternator regulated by a Balmar Maxcharge MC-612 reg.
At tickover and during early running all is well. The system charges and the tachometer works normally. After a while the tachometer drops to zero and charging stops. It can be recovered by dropping to low revs but as I increase the revs the tach drops off again. The obvious candidate is belt slip but there is no sign of belt damage and the alt seems to be spinning OK so I am wondering if something else could cause the same symptoms before I invest in a belt doubling kit. One mechanic pointed out that there is not much contact area on the alt so the doubling kit might be the answer.
I am not too worried about losing the charge, the solar is keeping up fine. I AM worried about losing the belt / water pump - particularly as I am heading down the NY East River in a couple of days...... Is there any way of making an alternator freewheel? Then it can just act as a tensioner until I can get this sorted.
Anyway, thanks for any input!
Graham (enroute to The Bahamas)
Beyond the other tips, turn off your solar, turn on some DC loads and let us know if this still happens....
Sounds to me like your solar controller has a higher absorption voltage than the reg thus it may be shutting it down when your are in the upper 90's SOC...
If that test works simply turn off solar if you want to keep the tach or up the voltage setting of the reg...
If this is happening in bulk mode then it is likely a bad reg or connection..
-Maine Sail / CS-36T
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Last edited by Maine Sail; 11-16-2013 at 09:57 PM.