It has either a generator or alternator style system. So ya your killing the battery and need to stop that till you fix the generator charging system. Check the fuses and wires for any breaks. May need a new stator or charging controller if the fuses are not the problem. May be even a bad ground wire.
You may just have a dead cell in the battery. The battery needs to be checked under load. Most shops will do a battery check for free. At least you can eliminate the battery itself as a culprit.
The brake light switch for the front brake is pressure-actuated. Is the reservoir low or empty?
Also, check to verify that the connector has not corroded, preventing the flow of current.
