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I have a USB cell phone charger combined with a voltmeter on my bike. I noticed on some of my rides, that the voltmeter will shut off and turn back on. At first I suspected a loose connection , but it turns out that it will stop charging my phone when the voltage gets too high.

When cruising at 40 miles an hour or faster, my battery voltage is 14.9 volts. When I roll to a stop, the voltage increases to 15.1 around 2000 RPM! Below that, it falls to 13.8 and settles at about 12.9 at idle. Bad rectifier? I have aftermarket pipes, so no GB adding heat to the rectifier.

My old bike had measured 16+ 4000 RPM when I replaced the rectifier. But as it started failing, it would suddenly jump between higher and lower voltages. The headlight would appear to flash as it jumped to the higher voltages. This time however, the voltage is steady and high, and creeps just a little bit higher as the RPMs drop.
 

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Could be the r/r, but check battery connections. My meter pegged with a loose cable, but it still had enough connection to crank the starter. The meter tops out at 15 or 15.5v, the light turns blue.
 

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My bike with a digital voltmeter going showed voltage up and down all the time. 12.8 at rest, 13.6 after start and would vary up from there to 15.1 while riding. Mostly stayed in the 14.2 - 14.8 range.
As it never stayed high for very long, and the fact it was a new bike with less than 2,000 miles on it, I was not concerned.
Last I heard the bike is still running great.
 

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I just recently got around to changing out the turn signals and the relay. So except for the gauges and dash the bike is all LED now. Since then I see a consistent .5 volt increase on my voltmeter that I have wired in to the front accessory leads. So based on RPMs or how long the bike has been running I see it fluctuate between 12.2 (fan running) up to 14.7 (at a stop after running). Have you compared the meter on your bike to a handheld meter directly across the battery?
 

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Discussion Starter #5
I haven't verified it with an independent meter. I might change out the rectifier with my other bike aftermarket one once I finally decide to park it for winter. I'm stubbornly still riding it to/from work. That way, I don't have to worry about it again.
 

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Would be a good idea to check the dash meter with another meter before you make any changes. Half a volt would put it just about right.
 

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Would be a good idea to check the dash meter with another meter before you make any changes. Half a volt would put it just about right.
Exactly, that’s the point I was making. Depending on where it’s wired in there may be a small voltage drop. Before I switched out the incandescent bulbs I always added a half volt to the reading.
 

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Agree, check it at the battery with a multi meter. Various RPM’s and see where you at.
I’m no expert but your range doesn’t sound that far off,
 
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