Since I worked in the automotive electrical field for several years here's a subject that I can address with some authority.
First, let's discuss the function of the battery in any vehicle. It has only one purpose. To provide sufficient energy to start the vehicle! (Okay, before someone calls me on it, in modern vehicles it retains the memory in the computer. The amount of current needed for this task is so minuet that we can ignore it.) Once the vehicle is running the battery should just be sitting there getting recharged by the current left over from the tasks of operating the machine. All of the lights, the horn, the radio, the cell phone recharger, the nav system etc. should be powered by the charging system. Unfortunately, particularly on scooters the charging system has very little left for recharging the battery. If you've accessorized your scoot you may have problems. I once had a customer who complained that the battery kept dying in his car. The reason? He had installed a super whizzbang stereo with two humongous amplifiers in the trunk that drew, by themselves 105 amps against a 90 amp alternator.
There are several things that affect battery life. The primary one is weather. Vehicle batteries do not like extremes, hot or cold. Another is how it's used. If you take only short trips, 20 minutes or less you may not be fully recharging your battery before asking it to do it's job (i.e. start your scoot) again.
Another factor is maintenance. Are the terminals clean, properly fitted and tight? What about any other connections in the charging system? Is the water/acid level where it should be? When topping the battery up do you use distilled water only?
Side note:
INITIAL CHARGING PROCEDURE: Once the electrolyte is in your battery and the battery caps are hand tightened, you should then charge your battery with a low-amperage battery charger. We recommend that a battery should never be charged at amperage greater than 10% of the amp-hour rating of the battery. For example, if you have a 10 amp-hour battery, a 1 amp battery charge is recommended. A 5 amp-hour battery should be charged at a .5 amp rate. You should allow approximately 10-12 hours to fully charge your battery. We also suggest using a charger that cuts off when your battery is fully charged.
Source:
http://www.ebatteriestogo.com/Activation_Charging_Procedure.htm