When the bike died I had the Ballistic evo 3 battery in it. It would not turn over. I installed an old backup battery to finish the track day. (Yup I took a backup!!!) I put the ballistic back on a maintainer when I got home. I took the maintainer off and 24 hours later took a reading of 13.57 volts.
The backup battery is currently installed in the bike for the testing. The battery started with 12.9 volts. When I hit the starter the voltage dropped all the way to 10 but the bike started fine. The voltage was steady while running at idle at 12.38 volts. When I revved the bike to 5000 and even higher I had a max reading of 12.43 volts.
The bottom part of my notes shows the voltage that I have coming out of the stator while running at idle and while running at 5000 rpm. 24 Volts at idle and 83 volts at 5000 rpm. Obviously the voltage was fluctuating a little bit but I took an average. Also you can see that the ohms readings that I had were either .3 or .4 ohms between all wires.
Attached is a picture of my multimeter, the backup battery which is in the bike, and my notes. More info to come...
Here you can see in the pictures the wiring harness coming off the stator. You can see how I set up the reg/rec for easy testing. You can also see the chart of my test results. The circled results are what I think are out of spec and I don't really understand what to do where there is an asterisk**** My testor just showed OL but I think I'm doing something wrong there not sure.
Ho-ly shit. That's a lot of detail. lol
So first thing- that lithium battery has to be tested as per manufacturer specs. Lead acid batteries are an incredibly different beast than Lithium Ion. 13.57 after a charge for Li/Ion looks promising, though. The rest voltages and load voltages are different between the types, but the charging voltages would be very similar (there are too many variable for them to be exact).
Second, it is typical for the voltage to drop when pressing the starter. In a circuit, voltage divides between components. Think of the water pipes in an old house and someone flushes the toilet or turns on the faucet while you're in the shower. If the toilet gets flushed, the water system cannot supply enough cold water everywhere, so the shower will get hotter for a few seconds. Your battery voltage drops because some of the pressure (voltage) goes somewhere else. If you wanna get pedantic, what I said wasn't a great example because of 'battery internal resistance,' but just remember battery voltage will always drop under load.
The asterisks in the manual mean that there should be no reading when measuring those components. O/L on your meter means "Open Line." O/L means that there is no circuit, and the meter cannot read any value. That's a nice meter, BTW...
When measuring stator output, there will ALWAYS be fluctuation in output voltage, first because the output frequency and voltage changes with RPM, and the meter has to do math with AC voltage and current. The meter takes what's called "RMS" voltage and current in AC circuits. Your meter is professional grade, so it will actually take longer for those reading in some cases because of the way it makes reading automatic and the user doesn't need to specify range.
Your rectifier is out of spec. It requires replacement. Once replaced, check the rest of the system, too. It doesn't look like anything else in forked, but better safe than sorry.