5 minutes! What amperage are you using to charge the battery?!
please do this for me, do not vary this at all.
Take the battery out of the bike. Set the charger to 2A or lower, hook the battery up, and let the battery charge over night. in the morning, take the battery to an auto parts store to get load tested. if this cannot be done, find a multi-meter, install the battery, switch your multimeter to VDC, attach the leads from the multimeter to the battery's terminals, note the battery's voltage, turn the bike on, hold the throttle wide open, as far as it'll go, start cranking. monitor the voltage of the battery while cranking for 10 seconds. if the voltage drops below 9 volts (there are there abouts) you have a bad battery and it must be replaced.
Release the throttle, and start the bike. take note of the battery's voltage. is it higher than before you started this testing regimen? it should be in the 13.x VDC range. now turn on your high beam and rev the motor to 5000 rpm and take note of the voltage. it should increase, but it should not be above 15.5VDC at any time.