1 Charging Woes Fri Aug 07, 2015 9:38 pm
brickrider
Life time member
I reluctantly turned back home recently when my 1985 K100RS charging light began winking.
I have an on-board after market computer that typically shows only about 13.6/13.7v. while underway, yet I've never experienced a battery so flat the bike would not start. I put the low reading down to error in the instrument's accuracy rather than an alternator that was failing. When the OEM instrument light began signaling me, I suspected the alternator was indeed bad. I had it rebuilt at an auto electric shop. Today I rode the bike for the first time with the rebuilt alternator and found, after a heat soak or two, the on-board v. meter reads about the same as it did before I had the alternator rebuilt. Back home, I used my multimeter (mm) to check voltage at the battery with the K-bike at idle and at 3k rpm. At idle the warning light glows faintly; at 3K rpm the mm reads around 13.7/13.8 volts. At that higher reading, the instrument warning light came on very brightly.
My mm is an inexpensive hobbyist model of unknown accuracy. I decided to do the same charging test on my 1983 R100RS. The R-bike read 14.1 at 3K rpm. If I'm not mistaken, that bike is rated at a modest 280 watts, yet it seems to outperform the K-bike!
At this point, I plan to check for parasitic load on the K-bike. To do that, I would connect my mm between the neg. battery ground cable and the engine with the ignition off, correct? There are other wires at the neg. battery pole. They should remain connected during the test, correct?
Thanks in advance for any suggestions/insights.
I have an on-board after market computer that typically shows only about 13.6/13.7v. while underway, yet I've never experienced a battery so flat the bike would not start. I put the low reading down to error in the instrument's accuracy rather than an alternator that was failing. When the OEM instrument light began signaling me, I suspected the alternator was indeed bad. I had it rebuilt at an auto electric shop. Today I rode the bike for the first time with the rebuilt alternator and found, after a heat soak or two, the on-board v. meter reads about the same as it did before I had the alternator rebuilt. Back home, I used my multimeter (mm) to check voltage at the battery with the K-bike at idle and at 3k rpm. At idle the warning light glows faintly; at 3K rpm the mm reads around 13.7/13.8 volts. At that higher reading, the instrument warning light came on very brightly.
My mm is an inexpensive hobbyist model of unknown accuracy. I decided to do the same charging test on my 1983 R100RS. The R-bike read 14.1 at 3K rpm. If I'm not mistaken, that bike is rated at a modest 280 watts, yet it seems to outperform the K-bike!
At this point, I plan to check for parasitic load on the K-bike. To do that, I would connect my mm between the neg. battery ground cable and the engine with the ignition off, correct? There are other wires at the neg. battery pole. They should remain connected during the test, correct?
Thanks in advance for any suggestions/insights.