My '91 FXR left me stranded after the battery ran out. Battery is near new original part. Put it back on (trickle) charge and, unsurprisingly, started beautifully after 1 1/2 days on charge BUT when I checked the charge after a 15 min ride it showed 18+ Volts without the engine running- dafuq? Alternator output was equally high at 80+ AV when revving medium high (got no tach). Once back home batt now shows a more familiar 13+ V. Alternator to regulator plug looks a bit ordinary so would perhaps the systems try to overcompensate by delivering a higher charge? How on earth can a 12V batt deliver 18+ V though still? Does having it on trickle charge all the time have an effect here? Might take it on a brief cruise with a voltmeter in my pocket to monitor but obviously there is a lot going on I don't understand... anyone got an idea? Also, can I just replace the plug or does the whole charging system have to be replaced as I've been told (might be its turn anyway, God knows its age)?
cheers...
If a battery is on it's way out or has been "cooked" from over voltage, the internal resistance can increase. This can cause the battery to show a higher voltage for a time after being on the faulty high charge state. I'd suggest your regulator may be stuffed, but make sure to check the earthing of the Reg.
To save me typing more, found this quick guide:
http://blog.jpcycles.com/step-by-step-instructions-for-testing-your-harleys-charging-system/
check charge rate @ the battery when hot after a 10 - 15 ride with the headlight on dont' , stop the engine before testing then you will know whats she up too
