[R6Ruckus]

Probably an issue effecting your stator. I'd disconnect it and use the reserve battery to get home till you can diagnose what is causing your stator to over charge the system.

 

[R6Ruckus]

what rpm do you ride at? one or two thousand rpm will also make a large difference. i'm sorry i wasn't more detailed, was just pointing out the fact it is safe to ride on battery power alone.

 

[R6Ruckus]

well, just referencing track rpm range - you can go as low as 2k rpm without hurting the engine. and you tend to accelerate out of turns, so there is a higher load on the engine then just coasting.
that is cutting your voltage requirements by over 50%

personally, I wouldn't go below 3

 

[R6Ruckus]

well you'll get multiple different answers here. most of which will be "they are always done in pairs" or something to that extent. to my knowledge of electrical circuits, the only safe way to verify you are good to after swapping out the stator is actively monitoring the charging system at all times, as the issue could happen after riding. the only way i can think of is semi-hard wiring a volt meter to the battery and monitoring the charging voltage.... but I'm not 100% sure that will show how much the stator is outputting.