Nice steady 11.7 volts

[hogfish]

Hello, everyone. I have a '99 SE. For 7 years I've had a Compufire alternator and AGM battery with no problems. I have a digital voltage gauge that has showed 14.5 volts consistently for all 7 years. Suddenly a few weeks ago the voltage dropped to 11.7, which I know is a problem because seven years ago that's what convinced me to get the Compufire. I thought that it was the alternator failing so I put a new alternator on (not a Compufire but a 90 amp). Started it up: 11.7 volts on the digital gauge and at the alternator and the battery with my multimeter! Checked battery when disconnected: about 12.2 volts. I got a new battery just in case and it reads the same as the AGM battery, about 12.2 volts disconnected and 11.7 volts when running.

I'm at a loss here, and have been checking the wiring drawings in the Clymer Service and Repair manual, and as I suspected there's really not much between the alternator and battery that I can see that can go wrong. One thing though, just in case (and I know it's strange to bring up, but that's one complicated schematic): I have never used the cruise control since I got this bike in 2011. A few days before the voltage drop situation I happened to push the Cruise Control On button; it felt like a worn out switch, wouldn't stay pushed in. I only mention it because it appears in the schematics that the cruise relay may connect in some way to Relay #6 which seems to go to the alternator.

Anyway, all relays are new, and I am out of ideas, and am asking for some help on this.

Thanks,
Ed

[Rambozo]

First check the sense wire at the alternator for battery voltage. If that is ok, you can measure the current output of the alternator to confirm. But it looks like you replaced one bad alternator with another bad alternator. Just because it is new, doesn't automatically mean it is good.

[hogfish]

Looks like Rambozo is right. The new one was faulty.

[thebruce]

There seems to be a rash of new/non functional alternators out there.

Rambozo's statement "Just because it is new, doesn't automatically mean it is good." Applies to so much more than alternators...

[Rambozo]

Seems like a lot of companies have made the end user their QC departments.

[MikeB]

Hello, everyone. I have a '99 SE. For 7 years I've had a Compufire alternator and AGM battery with no problems. I have a digital voltage gauge that has showed 14.5 volts consistently for all 7 years. Suddenly a few weeks ago the voltage dropped to 11.7, which I know is a problem because seven years ago that's what convinced me to get the Compufire. I thought that it was the alternator failing so I put a new alternator on (not a Compufire but a 90 amp). Started it up: 11.7 volts on the digital gauge and at the alternator and the battery with my multimeter! Checked battery when disconnected: about 12.2 volts. I got a new battery just in case and it reads the same as the AGM battery, about 12.2 volts disconnected and 11.7 volts when running.

I'm at a loss here, and have been checking the wiring drawings in the Clymer Service and Repair manual, and as I suspected there's really not much between the alternator and battery that I can see that can go wrong. One thing though, just in case (and I know it's strange to bring up, but that's one complicated schematic): I have never used the cruise control since I got this bike in 2011. A few days before the voltage drop situation I happened to push the Cruise Control On button; it felt like a worn out switch, wouldn't stay pushed in. I only mention it because it appears in the schematics that the cruise relay may connect in some way to Relay #6 which seems to go to the alternator.

Anyway, all relays are new, and I am out of ideas, and am asking for some help on this.

Thanks,
Ed

You posted this last month. Have you found the problem yet?