As noted in my recent post “Taillight Fuse Woes”, I've finally gotten my bike---1978 Cb550---to charge the battery and stop blowing taillight fuses. BUT . . .
While the battery charging seems to work---what I'm seeing on the voltmeter during a test run is not what I expected.
Test Ride Nov 11:
Starting voltage at the battery: 12.67v [I have a multimeter mounted on the tank and it reads the voltage between the pos & neg posts at the battery].
After an electric start, the volt meter jumps up into the high 13s and into the 14s once I get the revs up.
But within a minute or two of running the voltage begins to creep down---regardless of engine rpm.
Soon the volts settle into the low 13 range---even dropping briefly to the 12.90s (all the time with the revs anywhere from 3,500 to 4,500---engine speed doesn't seem to immediately affect the charge rate).
When the brakes and/or turn signals are used, the charge at the battery jumps up to mid-13s-to-low-14s---as if the charging system sees the electrical draw (brake light/flashers) and turns up the charge rate to replenish the battery.
These sequences happened throughout the ride---which included one stop and restart. On return to the barn the voltage at the battery was 12.96. Which later trickled down to the 12.67 I started with.
So, on the one hand the system seems to be working---voltage going out of and into the battery. But the way it's working is not what I expected to see based on what the manual says should happen. I expected to see a constant 14.5 volts of charge (or thereabouts) at and above 4,000 rpm. Instead, I'm seeing voltage numbers that constantly fluctuate.
Have I misunderstood what “14.5 volts at 4,000 rpm and above” means?
