Small Engines (Lawn Mowers, etc.): charging system, garage door opener, trickle charger

Question
A.C. volts is 21 so guess i will think about buying a new stator or just keep trickle charging bat. each night.

Answer
You would be correct, 21 volts/2 =11vdc. Not enough.
I use to have a "gold wing" that had an alarm. It would gradually drain the battery over long periods when I didn't ride.
I hooked a trickle charger to the outlet on my garage door opener. Every time the door opened or closed it gave my battery a charge.