Convert Internal Rectifier to External Rectifier

[zboss]

We are getting a new Beta Marine engine and they won't ship it without an alternator. I was thinking that since its only a moderate price to upgrade to the 175 Amp alternator that it would be an option we are interested in...

The alternator is a rebranded Mahle MG484 with internal regulation and an internal rectifier. We can get a kit that allows us to convert it to externally regulated but they don't offer an external rectifier option.

Does anyone know if its possible to modify an alternator like this for external rectification when it comes time to upgrade to lithium batteries?

- z

[zboss]

Or... do you think I am better off just getting the cheapest alternator and then getting the Mark Gasser or Balmar?

[Jammer]

It is difficult to modify an alternator for external rectification but it can be done. In principle, it is simply a matter of disassembling the alternator, disconnecting the stator leads from the diodes, and connecting the stator to the three (usually) output wires that will go to the external rectifier.


Disconnecting the stator is a matter of desoldering or cutting. If you cut, you will have to sand off some enamel insulation. Then you solder the new wires in place, and route them through a suitable strain relief or to a connector.


The problem is that you're working in an environment that is high temperature and are running AC currents over 100 amps, which means that the wires are going to vibrate from the magnetic field -- as well as from vibration transmitted by the engine.


It is not possible to provide overcurrent protection. Check your work carefully, if anything shorts out, your alternator will burn up.


That's the way I see it. I'll let you decide whether to try it, or send your money to Glasser et al.