If it is the battery, there are 3 possibilities:
1. You don't ride long enough+often enough to charge the battery.
2. The battery is bad and will not hold a charge.
3. The electrical system on your scooter is faulty and unable to charge the battery.
So, Charge the battery fully and have it tested at an auto parts or motorcycle store that can test it under load.
If bad, replace it with a AGM battery of the correct size and terminal configuration.
If the battery is good, then you may need to charge it more often or work on the electrical system.
With a fully charged battery, place the scooter on it's center stand and connect a digital voltmeter to the battery.
Measure the voltage at the battery at idle rpms, 2000 rpms and 3000 rpms. Be careful to keep the rear wheel off the ground and your
body parts away from the rear wheel because it will be turning.
The voltage should go up to 14.5 volts, but no higher. If so, then the electrical system is good.
If you don't want to do all this work, then replace the battery but remember to charge it overnight before use.
So, you will need a battery maintainer if you don't have one already. $20 at WalMart
Scoot safely,
