Mppt will be of little value to this exercise.
Syncing is only of importance if you wish to couple the ac lines for some unimaginable reason. Independently charging both banks does not require this kind of setup.
An adjustable regulator can be simply a rheostat (potentiometer) to control the power driving the rotor coils current. An alternator is a very simple device, dressed up by auto-electricians to look complicated. They are not.
They are simply a wound 3ph stator, with a single coil developing the magnetic field in the claws, going to a 3ph diode bridge to go from AC to DC....it really is that simple.
Next we can have internal or external voltage regulators, which sense the battery voltage, and supply the rotor with appropriate current to give a flux which when cutting the field coils will give a proportionate charge to the battery. As the battery gets near floating voltage, the rotor is given less current by the regulator, and magnetic flux drops.... and so charge rate drops.
At float voltage, it provides just enough rotor magnetism to allow the stator to develop just enough power to run the car/truck, but not enough to have excess to overcharge the battery.
It is a dynamic feedback system of supply and demand. The regulator simply controls the traffic.
Sometimes (mostly now days) they put the regulator into the alternator... thats where the above story arose. As you can see it is simple stuff to make your own. I don't have the schematic for it anymore, but the PCB file is still there I see. You will need to download protel autotrax from somewhere to use it ....it is free and less than 500k. It's a great little PCB program.
From that you can just change the zener from memory, and that will give you a different animal.
Remember, it is the turns per volt that dictate the alternators output. A 12v one can put out high voltage if you drive the rotor hard (more volts/turn) and spin it up faster.(more turns per minute).
So a 12v one driving 48v direct is not difficult. Just needs a new regulator and lots of revs... and maybe check the diode bridge to see if they can handle the extra voltage.
For what your doing, you want full belt anyway, voltage regulation is not the problem, you need them charged. If your EV is like mine, it can gobble up upwards of 100 amps easily... your alts are not likely to beat this, so will be playing catch up.... so a regulator may be a waste of resources, just a current regulator (eg light globe 12v 20W) acting as the current limit to the rotor will be sufficient. This is not to regulate the alts so much as to stop them stalling your Aux motor (which I assume is a small single piston thing). Your battery bank will keep the voltage under control until float voltage comes about.... not likely while your still driving.
In the unlikely event that it catches up to the batteries, then you can throttle back your aux motor, (use it for the rough regulator...less rpm so less output)....or turn it off.. or you could use a selector switch and switch in different light globe combinations for different charge rate regimes... sky is the limit once you come to understand how simple these things really are. Best economy is probably full bore or off..... which makes a regulator a waste of time really.
The real regulators themselves can be very unsimple (complex buggers) and sophistocated, but if you make your own using either a rheostat, globes or electronic like mine, you become the master of what happens.
All the best with it
.........oztules
