Hi Yin Ng, you can try connecting the battery to a trickle charger or battery tender with an automatic shut-off feature or float mode. This will ensure the battery doesn’t get overcharged. The battery can remain in the vehicle or be removed while it’s hooked up to the battery tender.
Other than that, you could unhook the car battery and hook it back when you need to use your car. By doing so, your car battery will not be drained even when the car is not in use.