Prestolite alternator not charging

[spyder777]

Recently bought complete mercruiser 140hp set up out of a 1972 starcraft to replace 110hp/1a ez-shift set up in my 1965 larson all-american. Came with mercruiser instrument panel and harness that connects to engine. Hooked it all up, and ran it on the stand. All gauges worked except ammeter, and alternator wasn't charging battery. Volt meter reads 12.3v at battery, and 44v at alternator. Alternator has one large red wire connected to it,and according to manual states its a prestolite. Any ideas why voltage reading is so high at alternator and not charging battery would be greatly appreciated.

 

[Howard Sterndrive]

Re: Prestolite alternator not charging

44V? wow- if you measured that correctly, the alternator output isn't connected to the ignition which is a good thing. 44V would have cooked every electrical component on the boat.
There was no "one wire" alternators in 1972 so the manual is not going to cover the alternator you are looking at.

I suggest you just take the alt off your 110hp setup and stick with what you know worked before.

 

[achris]

Re: Prestolite alternator not charging

44v sounds like the regulator has gone south (a LONG way south!). That could have been caused by the alternator being run without being connected to a battery (no reference). If you are handy with tools, just pull the alternator to bits and replace the regulator (and do the brushed while you're in there )... It's not a difficult job..

Chris.........