Battery Charge Voltage - Old 860GT
Posted: Thu Apr 07, 2016 9:36 pm
I was suspicious that the battery was not charging properly on my original 1975 860GT. The electrical system is original other than horn and turn signal deletes, and the addition of Lucas RITA ignition and a halogen headlight (no electric starter). The bike has the original 150 Watt generator and original regulator. I measured battery voltage with my crusty old analog voltmeter (50 volt scale) and saw ~12 volts at idle and no voltage increase under easy Revs. So I was a little concerned (actually, maybe I did not rev the engine high enough in this quick test).
I then disconnected the regulator, cleaned the regulator contacts, and measured the generator winding continuity and resistance to ground and found no problems. I did find a slightly high resistence measurement (<10 ohm) on the brown wire between the regulator and the fuse box. I re-crimped the conector at the fuse box and got back down to zero ohms (BTW this is not an original fuse box ..... I already went through the melt-down scenario and replaced with Radio Shack parts a long time ago).
I then repeated the battery voltage measurements with the headlight off with the following results ......
o Idle to approx 3000 RPM ......... ~ 12 volts
o approx 3000 RPM .................. voltage begins to increase above 12 volts
o 3000 RPM - 4000 RPM ............ voltage increases to about 14.5 volts max
I was about to buy a new voltage regulator, but the results now look pretty normal to me. I would appreciate the advice of the forum concerning my results and your experience with the electrical charging system of a 860. At this point I am thinking that it does not make any sense to replace the voltage regulator. Your thoughts?
Thanks and happy riding !
Old905Duc
I then disconnected the regulator, cleaned the regulator contacts, and measured the generator winding continuity and resistance to ground and found no problems. I did find a slightly high resistence measurement (<10 ohm) on the brown wire between the regulator and the fuse box. I re-crimped the conector at the fuse box and got back down to zero ohms (BTW this is not an original fuse box ..... I already went through the melt-down scenario and replaced with Radio Shack parts a long time ago).
I then repeated the battery voltage measurements with the headlight off with the following results ......
o Idle to approx 3000 RPM ......... ~ 12 volts
o approx 3000 RPM .................. voltage begins to increase above 12 volts
o 3000 RPM - 4000 RPM ............ voltage increases to about 14.5 volts max
I was about to buy a new voltage regulator, but the results now look pretty normal to me. I would appreciate the advice of the forum concerning my results and your experience with the electrical charging system of a 860. At this point I am thinking that it does not make any sense to replace the voltage regulator. Your thoughts?
Thanks and happy riding !
Old905Duc