Voltage regulator

[ghostlymoron]

I've seen pictures of boats where this has been done but tbh I have neither the room nor the inclination to attempt such a project. My boat is too small and the engine space too compact. My electrical requirements are small. A further restriction is the power of the engine, 9hp, and an alternator could take 2hp apparently. I'd rather keep it all for propulsion.

 

[oldharry]

I can't imagine why asolid state regulator will give more charge current than existing reg . Charge current will depend on the regulated voltage to induce more current into the battery but more likely this current will be limited byt he generator itself and its speed.
Control of voltage out of the gen is most efficently done by controlling the field current. More current more field magnetism so more output volts/current. I can't imagine how reducing voltage anywhere will increase current.
l

The coils in a mechanical regulator take some current to operate them. Even half an amp is a significant draw when only 8 amps RMS is available. A solid state regulator needs a a few milliamps to operate. A small but significant saving on a low output unit like a Dynastart! As you say, the field coil regulates the output, and the VR controls the field coil. If the VR is in the positive supply to the field coil, then increasing the VR output increases voltage in the field coil. If, as in the Bosch unit, the VR is on the negative end of the Field coil, then as its Voltage rises, so the voltage developed across the Field coil is reduced. So if the VR rises to 3 volts output, then the voltage across the Coil is reduced to 9 volts. It has the same effect as putting a variable resistor between the coil Neg connection and its ground or frame and was a common early way of providing manual voltage control of a DC generator. It has the advantage that the VR circuit is running at low voltages, needing even less power to operate it. It was an attempt to save power losses in the control boxes that Bosch did it this way. Also, the solid state regulator gives a much smoother and more constant output, particularly if the original mechanical one is already well worn!

 

[VicS]

I've seen pictures of boats where this has been done but tbh I have neither the room nor the inclination to attempt such a project. My boat is too small and the engine space too compact. My electrical requirements are small. A further restriction is the power of the engine, 9hp, and an alternator could take 2hp apparently. I'd rather keep it all for propulsion.

I guess space is already pretty limited .


You can always get around the power drain issue by fitting a field switch to stop it generating when you need all the power for propulsion. In fact I think there was something similar fitted to Dynastarts on small engines.