I am not sure that this has anything to do with your problem, but you are making assumptions and that can be dangerous when diagnosing faults.
Check the fluid level in the battery.
These bikes tend to be a bit thirsty on battery fluid normally, and if it has been on the battery tender for any length of time, it may have dried it up a bit too.
Check the charging voltage with the revs above 3k rpm.
Check the battery voltage when starting.
Get back to us with your findings.