It really is that simple. Every time you take your car for a drive, its alternator (a little generator connected to the engine) produces electricity that keeps the battery topped up with electricity. Longer drives are be. If you don't drive your car regularly (for instance, if you have a classic car that lives in the garage for months at a time), it's worth buying a battery charger. Simply connect the batte. Smart battery chargersare great. They perform basically the same function as a conventional charger, but they have a couple of extra tricks. The biggest boon is that they can rec. Some sources suggest idling your car's engine is a good way to charge a dead battery. It isn't. Alternators are designed to keep a battery topped up, not recharge it from empty. Atte. If your car battery is repeatedly going flat, but there's no obvious cause, you can test the voltage with a battery tester. With the engine turned off, attach the tester to the battery. If you se.