QuestionHi. I have a 1965 cb160. I check the voltage at the battery while running and
always seem to get a different reading. It ranges from just over 12 volts to just
under 15 volts. I understand that the rectifier converts A/C to D/C current, but
what regulates the voltage?
AnswerJerry, a permanent magnet charging system needs revs to make more volts, so you will see the voltage rise from 12 at idle up to 15 or so, above 2500 rpms.
Wiring diagram here:
http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php use CB/CL160 diagram.
Honda designed the charging system to only put out 1 or 2 amps, no matter what the voltage output is. Charging system output is a function of the strength of the magnets on the rotor, the number of windings in the stator, the number of phases of AC voltage and the condition of the diodes in the rectifier. Original rectifiers were selenium and not as hardy or efficient as silicon diodes that came later. Honda did add a voltage regulator on the 350-360-450 twins, as they had a larger charging system which could overpower the battery's ability to absorb the charging output at high speeds.
Note that the third leg of the charging system isn't used until the headlights are turned ON, then the electrical load is balanced with additional current/voltage from the third phase of the stator.
Short answer is that your system is working as designed without a separate voltage regulator.
Bill Silver
