Odd, Intermittent Charging Problem
Here's one of the ways a dash mounted voltmeter can be a good thing. I'm open to suggestions if anyone has something, haven't got to check it out yet.
For a couple of seasons, I've been thinking the JB fan relay was pulling the charge volts down, because slow traffic with the fan on is when I noticed this. So I thought it was heat and the fan combined to cause this, but now I don't think so.
Symptom: Rolling onto the throttle, engine hesitates and backfires. At speed, won't rev over 4k. Every time this happens, I look at the voltmeter and it's down around 12-12.5v. It's random and doing it when the fan is off. It goes maybe a minute or two at low voltage, comes back for a few minutes, rinse/repeat. Revving it up makes no change, it just comes and goes on it's own. Once, I pulled the choke while trying to speed up and there was no change, just 4k rpm and bogging.
When the charge volts are 13-14.5v, it runs fine and revs to the limit. On a 50 mile ride it kept going in/out of the low charge condition. Battery is 5yr old agm, seems fine, always starts, stayed up all winter with no tender, but I wouldn't rule out an intermittent short, yet.. Seems like a short in the battery would drop a lot more voltage, the voltmeter looks like the charging system quits and it just shows battery voltage.
It's got a TPE stator and Shin. mosfet r/r. Looks like this might be hard to pin down. Need to find that ohm test for the mosfet. Anyone have it?
I suppose first I'll check connections, but the time it had a loose battery terminal, the charge pegged at 15v.