GM10 alternator?

[Niander]

Hi can i fit a more powerfull alternator to my GM 10
are there any limits on output or anything like that ?
will any yanmar alternator fit?
so long as the lugs etc are the same?

 

[mikejames]

I think you will find that unless it is combined with an intelligent slow start alternator regulator the engine will tend to stall when cold if it is presented with a bigger load than the existing 35A alternator. The 35 amp alternator is demanding close to 1HP when you take in account losses.

Some saildrive 1GM10s have time switches in the alternator control circuits so they dont load the engine for some time after starting even with the standard alternator because of this problem. (also manifests as ... start the engine, motor off slowly and 2 minutes later it stalls for no reason )

With my older 1GM it can be annoying having to run the engine in fast tickover for several minutes when the batteries are flat before moving off while the boat inside on the raft is waiting for you to go.
You just know the engine wont keep running in gear if you rush it ...

 

[Gunfleet]

Adverc suggested to me switching the alternator so the diodes aren't excited when you start the engine. Works for me. Having lots of compression helps too!

 

[Niander]

Is that easy to wire?

 

[Gunfleet]

Yes. Ask Adverc and I'm sure they'll explain direct. Or if you are unsure take the alternator you want to use to an auto electrician and tell them what you want to do. It is easy but you do want an expert to tell you how. I run an 80 amp Lucas alternator on my Yanmar 1GM10, by the way, but I don't switch it on until everything is up and running. With the alternator switched off I can start the engine by hand. My local auto electrician tels me the Bosch equivalent, off any Ford Escort in a breakers near you, is just as good if not better.


ps I don't know why the hell I wrote 'diodes excited' before... I meant fields of course. I was excited.