This is in a motorcycle. I'm having issues in the charging system.

I tried to rule out some things by connecting the output of the regulator directly to the battery, but the voltage is lower than when connected regularly. Why would that be?

Also why is the R/R output less than 1 volt if the output cable is unplugged? (probably related questions).

  • Don't know much about MC charging systems, but wondering if it needs a field charge to create the voktage? Feb 16, 2017 at 3:13
  • 1
    What bike? What do you mean by, "connected regularly"?
    – raydowe
    Feb 16, 2017 at 16:00
  • I mean connected to the wiring harness, which is connected to the battery. Or connected directly to the battery not through the wiring harness. Feb 16, 2017 at 19:45

2 Answers 2


I don't know what is R/R? but the reason for "1 volt" is because you need electricity to create energy with alternator. Because they do not use permanent magnets, they rely on electricity to magnetize the coils. Also part of the generated electricity is used to generate even more energy. This won't happen if the alternator is completely disconnected from battery. Also as an example you have a car with completely flat battery, you can't start it by pushing. You need at least some power in battery to get the alternator do some work and suplement the battery when push starting.

About the output of regulator when connected to battery. Shouldn't the harness be connecting it to battery anyway? How much is the difference in voltages? does that count for cable losses? You may want to read the following : http://www.electrosport.com/technical-resources/technical-articles/how-motorcycle-charging-system-works : I can try to update the answer if more information helps figuring out the reason.


Is the output of the regulator designed to control the alternator? Which may be why it is less than 1 volt when disconnected... You need to make sure the output from the alternator is getting to the battery and investigate why if it is not.

  • This is a speed triple that has a stator as one unit and a regulator/rectifier as another. There seems to be a difference between when I connect through the wiring harness and directly to the battery. But I don't understand the theory of why when the R/R is disconnected entirely it reads less than 1 volt Feb 16, 2017 at 19:45
  • The stator produces the energy to charge the battery, controlled by the field - usually generated and controlled by the output of the regulator which is fed to the rotor. Are you sure it is a combined regulator / rectifier? The output from the star is usually what needs to be rectified.
    – Solar Mike
    Feb 17, 2017 at 8:50

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .