Tach needle jumping around...

[cajun31]

The only time I ever saw mine go up to 15 plus is when my voltage regulator was bad. I honestly can't remember what my tach was doing though. I replaced the voltage regulator and everything went back to normal.

[bikerphil]

Well Jonny, it looks like either obtain another tach and try it, or continue going through the wiring, cleaning all related connectors. At this point it could be either or maybe even something else. Operating on a tamper proof tach might not be for you. It's an extremely finicky task.

[motoman]

15 sounds a bit too high, are you running a lithium battery? I'd be leery of anything higher than about 14.4 with a lead-acid battery.

The tach itself is reading off one of the stator windings which would be an AC voltage somewhere in the 50v+ range.

Actually LAB3, A lead acid wet cell battery on a 12V system, the regulated voltage with system running and working correctly, regulated voltage correctly should show to be 13.8-14.2volts. That comes from having 50+yrs. experience diagnosing 12v d.c. elecrical systems in the automotive world. That may also be of help to many others here.

[motoman]

LAB3, no offense intended by my previous post, just factual knowledge.

[LAB3]

LAB3, no offense intended by my previous post, just factual knowledge.

None taken. After living over 20 years with an off grid power system running 12v lead acid batteries I have a good bit of charging system experience myself. Anything over 14.2 would be suspect in that scenario although I've seen people bump that set point up a bit to 14.4 with AGM.

[JonnyO]

15 sounds a bit too high, are you running a lithium battery? I'd be leery of anything higher than about 14.4 with a lead-acid battery.

The tach itself is reading off one of the stator windings which would be an AC voltage somewhere in the 50v+ range.

I don't believe so. Just an Interstate. I don't think they list a lithium for an XS. I've had it for a couple of years.

[JonnyO]

Maybe the trickle charger has eventually done something not good? Battery shows 13.18 after unplugging charger and revs up to 14.81 on choke.

[cajun31]

Maybe the trickle charger has eventually done something not good? Battery shows 13.18 after unplugging charger and revs up to 14.81 on choke.

That sounds normal. There are six cells in a battery. Each cell carries about 2.2 volts. Doing the math that comes to 13.2 volts. That is approximately what you will have on a fully charged battery. It only drops after trying to crank the motor. 14.81 is also good which shows that the alternator and the voltage regulator/rectifier are doing there job. When you stated 15ish that indicated exceeding 14ish which is not good. Back to checking your settings on what Phil said to check on your tachometer problems.

[JonnyO]

That sounds normal. There are six cells in a battery. Each cell carries about 2.2 volts. Doing the math that comes to 13.2 volts. That is approximately what you will have on a fully charged battery. It only drops after trying to crank the motor. 14.81 is also good which shows that the alternator and the voltage regulator/rectifier are doing there job. When you stated 15ish that indicated exceeding 14ish which is not good. Back to checking your settings on what Phil said to check on your tachometer problems.

Aye aye. At this point I'm leaning towards buying a good tach from a member-just to rule it out.