Rectifiers, regulators and battery charging.

The question is prompted by a concern about the possibility of "overcharging" the battery with an outboard that is not fitted with a regulator. Perhaps this is an unfounded concern with 5 or 6 amp stators in smaller engines?

I notice that larger engines are often fitted with higher output stators and a combined rectifier/regulator.
Can someone explain how these regulators work.
Do they really regulate the output from the stator, if so how. They cannot control the field strength like they do with "proper alternators" on inboard engines as that comes from permanent magnets in the flywheel. So how do they regulate the DC voltage. Are they shunt regulators, I would think that would require to much heat to be dissipated. Are they pulse width modulated devices or what?

Sorry for such a technical question.

Re: Rectifiers, regulators and battery charging.

Look in the Force outboard forum and you will find a post about a Universal regulator that works well on outboards that came with rectifiers. It does prevent overcharging/boiling batteries, and is easier on any electronics you may add to the boat.

Re: Rectifiers, regulators and battery charging.

Vic, I am not sure how the VR operate. They may shunt the excess voltage to ground. My 150HP Johnny has a water cooled VR with a 35A charging capacity. My 135HP Merc has dual 20A VRs that are bolted to the water jacket cover. I guess they get enought cooling that way.