[motobear52]

Don't know if this helps or not, but my '16 SDGT never shows above 13.7v on the voltmeter, regardless of rpm. All my other bikes register 14.3v.

After owning my GT for 7+ years, I don't worry about it anymore. But I do leave it on a Tender, 'cause if I don't, the battery isn't strong enough to start it, if it sits for over a week or more.

My problem is the battery voltage drops from 12.1 to "battery low" warning on the display over a 30 minute commute.
The battery tested fine , and is less than a year old. I too have the bike on a tender every time i park it at home.

 

[motobear52]

According to Haynes:

Alternator stator coil resistance	0.15 to 0.5 ohm
Output (capacity)	12V, 450 W
Regulated (DC) voltage output	13.5 to 15.0 V DC @ 5000 rpm
Unregulated (AC) voltage output	min. 50V AC @ 4000 rpm
Current leakage	max. 1.0 mA

Thank you for the specs.
the stator output is only hitting 40 vac across the windings at 4k rpm.
the coil resistance is .2 across each pair. should the dc level at the battery terminals increase with rpm?
The haynes manual says it should.
Can I check the ac input values at the rectifier?
If I replace a part, should I replace both the stator and rectifier.?