1. maintenance free or normal acid battery all are same.
to perlong their life span, you NEED to take them out and charge them full (a day or two) with battery charger, do it on monthly basic.

2. if possible, try not use any electronic or charge your phone in car.

3. you might switch to higher voltage battery, (newer car came with overload protection, not worry fry circult, just burn main fues). if the battery level drop below 90% thats you will not able to start the car, this is the stupit tech ever invented.