So should I not use this setup? I was thinking this would be a more efficient way to run the charging system. Since I am going to be using a much smaller 12v 5ah battery kick only, with no turn signals.
Neither the Vreg or the Rectifier will make the existing alternator more efficient.
I just don't know if this regulator is compatible with the grounded field coil, (as Bodi pointed out.)
For discussion...
The standard mechanical regulator switches the alternator field between 12 to 6-ish to 0 in response to the battery voltage. Since the battery voltage changes are linear, the mechanical switching frequency switches at a rate to provide whatever alternator power there is to the battery as needed in a linear fashion, due to the very high impedance that the battery provides to the circuit. A linear circuit isn't necessary, as the stepped voltage, while more akin to a three level digital signal is moderated by the battery. (Remember CDs put out digital signals but all the transducers in the path between generation and the human ear input, pretty much obscures any felt/perceived digital origin.) The battery and bike are similar recipients of the digital stepping of the mechanical regulator. In short, it doesn't care if the vreg is mechanical or linear operation.
Substituting an electronic regulator only changes the deterioration dynamic of the mechanical points wear. So, mechanical ones need adjustment after 30-40 years, depending on how hard the regulator has to work over those 30 years.
If you let the bike's battery deplete routinely, add more electrical loads, allow the wiring connectors to deteriorate, the vreg has to cycle more often to try and maintain battery state, and put max currents more often through the point contacts.
Depending on the regulator selected, an active device switch consumes some small amount of power and lowers the voltage driving the alternator to make power. Whereas, a mechanical switch contact in good condition provides the full battery voltage to the alternator field so the alternator can put out the most power possible, (given the RPM is optimal).
The electronic regulator in the 79 750 may not care about the absolute max output of its alternator due to the higher output that model has relative to the CB750 70 model. I suspect the 79 alternator in good condition will put out much better than the 210 watts the 70 model does.
Anyway, touting an electronic regulator as better at charging the SOHC4 battery than the mechanical one in good condition, is mostly sales pitch, IMO. That probably sounds odd coming from an electronic engineer of 30 years. But, there it is.
In fact, there is speculation and some evidence that pulsing the battery during charge is actually beneficial in disrupting cell sulfation deposits. But, I have some doubts.
Cheers,
