Electrodyne self exciting alternator

[capta]

We have just pulled this baby out of storage and installed it. Seems to work OK, but when the engine is off it eats electricity at about 5 amps.
We connected the positive to the house positive buss bar w/ a circuit breaker, the negative to an engine ground and the tach lead to the old alternator's tach wire. It functions OK, as well.
If it's leaking electricity like this, does that mean the alternator has a bad diode? I had the unit checked out before I left the states, but it has been stored in a dry place since then.
Thanks

 

[kloudie1]

Bad main diode or something ge-framitzed in the regulator..

 

[Justin_NSA]

What is a "self-exciting" alternator? Is it a magneto?

 

[LeslieTroyer]

my guess is that it is the same as a 1-wire alternator

 

[Rich Stidger]

What is a "self-exciting" alternator? Is it a magneto?

My understanding that a self-exciting alternator or generator is one that has some residual magnetism in the rotor so that when it starts spinning a small amount of current is generated. This current is then fed internally to the rotor winding as a positive feedback and the generation of current is increased. Thus it does not require an external input to the rotor winding in order for the unit to begin generating. The field windings (stationary) are the ones that generate the output current for the unit.

 

[Justin_NSA]

I think you are both right. More than you need to know about self-exciting alternators

 

[LeslieTroyer]

a generator is by definition is self exciting

 

[capta]

Well, we ran the boat around to Tyrell Bay from Hillsborough for duty free fuel yesterday and the alternator worked very well. However, it still leaks amps when the engine is off. As a self exciting alt I wondered if putting a diode in the charging line would mess up the self exciting function. We put a circuit breaker in the positive line, so when we kill the engine we can just pop that and stop the problem for now. Hopefully, we'll always remember to turn the circuit breaker on before we start the engine, but perhaps, with a self exciting alt, an open charging line isn't a problem????

 

[Gunni]

Just do a lock out tag out. If you can't hang the ignition key on the alternator breaker, hang something on the starter switch to remind you to go set the breaker. Go sailing.

 

[kloudie1]

good short term solution, Capta.. but the one bad diode is probably costing you 20-30% capacity..

 

[capta]

Just do a lock out tag out. If you can't hang the ignition key on the alternator breaker, hang something on the starter switch to remind you to go set the breaker. Go sailing.

Yep, out comes the Dymo labeler today. Lots of new red labels getting stuck on around the cockpit.

 

[jssailem]

out comes the Dymo labeler today

Such a message raises a concern.

 

[capta]

good short term solution, Capta.. but the one bad diode is probably costing you 20-30% capacity..

Yes. But it still puts out plenty, which is great while the generator is down. Next step is to find a parts supplier for the diode packs and whatnot, while I'm at it. Unfortunately, we're headed back to Bequia where the internet makes one long for dial-up speeds, if it's even working, so it'll be awhile.

 

[capta]

Such a message raises a concern.

Great pic, thanks.