I Have A Sears Tractor With A 12HP Briggs Motor the Discharge Light is on Battery is Full Charged and when it is running I have 13.6 volts into the battery if it sits it will not start

Check volts after sitting, probably bad battery. Charging system is working not likley a drain.

Don

Battery volts are still good after sitting tractor starts but discharge light still on tried to change bulb but still thr same