Hi Dr Zogg, another way is to make a large battery charger. You could get hold of a transformer such as an old welder transformer add a rectifier and presto, monster charger. That way you don't have to change the speed of your generators. Like Oz says most generators have inbuilt regulators, or just have a simple setup with a couple of diodes on the rotor and a capacitor across the exciter windings on the stator. Lowering the voltage by lowering the speed would also be a problem as far as cooling goes. The windings say on a 6kva generator would only be good for 20 amps or so max.
I have used large 50 volt 50 amp transformers in the past to make battery chargers, then used a 2kw light dimmer to control the primary voltage to set the output current. Of course you need to keep an eye on the batteries. I see it as better than running the system through a regulator really as one the regulator cuts in you end up with an engine chewing petrol up for nothing. Unless of course you have the regulator set up to turn the motor off when it reaches float voltage.
I also have a 5 hp Chonda motor with an 80 amp alternator ( my system is 12 volt) and that works great, I just put a rheostat from the output to the field connection to control the output current. Simple and effective. I think I bought a couple of 50 ohm 50 watt rheostats from Hong Kong, they were really cheap and work great.
Good luck
Pete
