Motorcycle Repair: Battery loses charge, regulator rectifier, battery terminals

Question
Hi there.
My scooter's battery keeps losing its charge.  I bought a new one, and it does the same thing.  Could this be the regulator/rectifier? Or could this be caused by many things?
Thank you.

Answer
It could be the charging system isn't keeping up with the load on the battery. Put a multimeter on the battery terminals and watch the voltage. When the bike is shut down you should see about 12.5 volts with a fully charged battery (maybe more if its new). With the bike running, you should be getting 12.5 to 14.5 volts as you rev the motor.