Yamaha 75 2 stroke over volts

[Murdo]

Hi, looking for some guidance to assist my own troubleshooting:

Was out for a few hours yesterday and noticed the voltage reading (from Garmin GPS) considerably high - up to 17volts at 5000 rpm.

Once at idle, dropped back to circa 13 volts. Did a hand test on battery and no obvious hot spots (access is limited though). All electrics ok thankfully.

Just going to check battery connections clean and tight and put voltmeter across terminals to see if it’s the battery. (I figure get the easy stuff done early).

What else could it be - will check all bullet connections under the outboard hood too but if all tight. What next - new rectifier needed?

Forgot to add - Yamaha 75 CETOL 2009 autolube.

Thanks in advance for any steers.

[Murdo]

So, a bit of an update:

Tach was dropping to zero yesterday intermittently.

Voltage was 12.7 at test today (engine off).

All points to the rectifier / regulator circuit I think, but will probably get battery checked anyway. Is there anything I’m missing on this theory and I assume engine shouldn’t be run until the issue is remedied?