There are two main ways to charge a car battery: with an external charger and with your car itself. The majority of external chargers out there today are “automatic,” or “smart,” but they just throttle down the amperage based on how much the battery can accept at a given time. Though they can be frustrating when they don’t work like we want them to, they often prevent batteries from overheating and exploding, which is a possibility with older manual chargers. If you don’t have a charger then you can make sure to charge up your car’s battery by going for a longer drive, for perhaps 30 minutes or so, which (assuming the charging system is working properly) gives the car plenty of time to fully charge the battery. If you only have a number of short trips in your week, and no access to an external charger, then mixing in a longer drive can help.