If you are on you 3rd set of bulbs, I would be looking into a wiring issue, probably shorting out to ground. Alternator could cause that too, if the regulator is bad and it is spiking up to too many volts.
-2001 Jincheng Panda(Honda Clone)
-1985 ATC70 with 125cc motor
-1973 CT70 with 125cc motor