How Long Does It Take To Charge A Car Battery With A 12V Charger?

Whether you're dealing with a dead battery on a cold morning or just trying to maintain your car during long periods of no driving, knowing how to properly charge a car battery is important. A reliable 12V charger is a great solution to bring your battery back to life, but the process isn't always as quick as you might think. So how long does it take to charge your battery with a 12V charger?

Typically, charging a dead battery back to 100% can take anywhere from 10 to 24 hours. But if you can't wait and need to get back on the road ASAP, you can usually head off after four to eight hours of charging. All of this depends on the charger itself of course, as results can vary from one brand to the next.

When charging your battery, be sure your garage is well ventilated or that your car is outside and you should always wear safety equipment like protective glasses and gloves. You should also consider using a backup battery in your vehicle's On-Board Diagnostics II port to ensure your computers maintain memory throughout the charging process.

Using a 12V charger on your car's battery means getting back on the road at full strength in about a day or so. If you simply can't wait that long, you can usually start up and get rolling on a partial charge in less than half that time. But assuming that's not quick enough either, are there any other options?

​You can charge the battery with a jump starter, which is a portable device that delivers a burst of power to a dead car battery. This allows the engine to start immediately, working much faster than a 12V charger. But while that's impressive, jump starters are intended for emergency use only and are not a permanent solution. You could also jump your car battery with jumper cables, provided you have a set and someone's around to pop their hood and give you a hand. But like the jump starter, this will only work in the short term.

Then there's the notion that relying on the car's alternator to charge the battery is the way to go. But you would have to drive at speed on the highway for that same four to eight hours at least, and that still wouldn't give you a 100% charge. The problem is that the alternator is busy running your car's electronics and is just not a viable option for fully charging the battery.