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Discussion Starter #1
My battery died. I realized while I was riding it was gone because the display went out. However at higher rpm the display comes back on so I assume the charging system is working.
The battery was tested by a shop recently so I'm ruling that out as a cause.
What could be the issue?
 

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It's hard to say without further testing.

I wouldn't rule out the battery at this point. They can become defective literally overnight.

Test for voltage at the battery first, both before starting, then at idle. Check the voltage at somewhere over 3000 RPM as well.

You should be reading something higher than 12.6 volts for a fully charged battery and in the neighborhood of 14 or higher at 3000 RPM.
 

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What kind of bike? Some are 3-phase and some single-phase, which will direct the troubleshooting. Also, some are fixed magnet, and others true alternators, which will also affect diagnosis.
 

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Typically the alternator puts out HIGHER voltage the higher you rev the motor, up to a point.

You need to test your battery, your alternator, and your charging system, in that order.

You might have a short in your system, for example, that prevents charging and discharges the battery UNLESS you're at high enough RPM to "wake up" your display, for example.

Or your alternator, if it's a true 3-phase alternator, might have one or two phases not working, either due to a burned out diode or failed winding.

Generally watching battery voltage A) engine off, B) at idle, and C) above 3000 rpm's will give you enough info to decide what is not working, or post it here and let someone interpret the results 4 u.
 
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