Searching for a replacement alternator

[4arch]

I have a Perkins M50 engine with what I assume to be the original 75 amp Prestolite alternator (picture included). At some point it was converted to externally regulated as it has a Balmar regulator. I also believe this engine requires an alternator with isolated ground. The existing unit has a 3.15" foot mount. I'd like to recondition the existing unit and keep it as a spare to be replaced by a new alternator. I've looked for a drop-in replacement and it seems that it's no longer made. I plan to do some "off grid" sailing but will have a sizable solar array so I'm hoping to not need to rely too heavily on the alt. I'd also prefer not to get into changing out the v-belt at this time. I'd appreciate some suggestions on what to look for in an aftermarket replacement and what questions to ask. The options are very confusing and I don't want to end up with something that doesn't work.

 

[Maine Sail]

I have a Perkins M50 engine with what I assume to be the original 75 amp Prestolite alternator (picture included). At some point it was converted to externally regulated as it has a Balmar regulator. I also believe this engine requires an alternator with isolated ground. The existing unit has a 3.15" foot mount. I'd like to recondition the existing unit and keep it as a spare to be replaced by a new alternator. I've looked for a drop-in replacement and it seems that it's no longer made. I plan to do some "off grid" sailing but will have a sizable solar array so I'm hoping to not need to rely too heavily on the alt. I'd also prefer not to get into changing out the v-belt at this time. I'd appreciate some suggestions on what to look for in an aftermarket replacement and what questions to ask. The options are very confusing and I don't want to end up with something that doesn't work.

I would suggest contacting Mark Grasser DC Solutions. He has a great 3.15" saddle mount alt that would very likely replace your Prestolite and maintain the correct offsets. He can also re-build your old one.... Your engine should not require islolated ground unless you own a metal boat... Isolated ground is a nice to have feature but adds tremendously to the cost of an alt. I know on my custom built alts that feature adds over $65.00 in cost, at my end alone....

I would suggest going to 120A then derating the alt to about 80A of output in "Belt Manager" or "Amp Manager", this depending upon the age of your Balmar reg.

 

[4arch]

Maine,

Thanks for the feedback. I will get in touch with Mark Grasser. One thing that's confusing about the Perkins M50 is that it's supposedly an isolated ground engine which led me to believe the alternator would need to be as well.