Charging your dead car battery is a bit more complicated and possibly more dangerous than charging your phone. One wrong move, and you’ll get shocked or sprayed by battery acid.

There is also the issue of charging the battery long enough so that you don’t get stuck with a dead battery again. This article will teach you how to safely charge a car battery and give you some emergency tips to keep in mind.

Before we get to the nitty-gritty of the post, you should be familiar with what a car battery does. It has two goals:

  1. It supplies your car with the power it needs to turn on.
  2. It keeps your car alive and moving.

A car battery provides a constant stream of energy to keep the engine and everything inside running, including accessories such as the headlights, radio, and any computerized components. A weak or old battery can’t do either of these things. Charging your battery can help determine whether or not you need a new one. A weak battery that needs to be changed won’t hold a charge no matter how many times you charge it.

How to Charge a Car Battery

how to charge a car battery

Before charging your battery, start with these five steps.

Read Your Manual

Since every car is different, your make and model might have particular instructions. Always refer to your manual before initiating a recharge.

Safety First

Before charging the battery, consider your surroundings. Make sure to park in an area free of flames, sparks, or smoke. Take off any jewelry, as it can be dangerous when charging. If you have some, put on safety gloves and glasses.

Foul Smell

Inspect under the hood. If you smell something that reminds you of rotten eggs, the battery may be leaking. DO NOT try to charge the battery if that is the case. Opt for the safer solution: stay away from the car, call the professionals, and have them take a look.

Incoming Heat

The heat emitted from the battery case might indicate that it’s been overworking. If that is the case, keep the hood up and let it cool before attempting to charge it.

Look for Corrosion

Usually, corrosion is a product of battery acid fumes coming into contact with the air—while it’s pretty common in most batteries, too much of it can compromise your car’s electrical system and make it more difficult for the battery to charge. To remove the corrosion, clean it up with a brush and a mix of water and baking soda.

How to Use Car Battery Chargers

All good? Let’s get to it. If you’re lucky enough to have a battery charger in the car or know someone who can bring you one, follow these steps. (You can find basic car battery chargers at most auto parts stores.) 

  1. Connect the Charger to the Battery.

First, before you turn on the charger, make sure your car is off. Next, connect the positive (red) clamp to the positive port of your battery.

Now connect the negative (black) clamp to a stable area on the car’s body. While you could also attach the black clamp to the battery’s negative port, we don’t recommend it. If the battery is leaking hydrogen gas, even the smallest spark could cause an explosion.

  1. Prep the Charger.

Adjust the volts and amps on the charger. Lower amps will take longer to charge the battery, but it may also lead to a more stable charge. If you’re in a hurry, switch it to high. Just be sure to follow the instructions that come with the charger and refer to your owner’s manual to ensure you are doing it right.

  1. Turn on the Charger.

Most portable chargers don’t need to be plugged into a power supply. Just flip it on and sit back. Depending on the type of charger, it may stop on its own once the battery is fully charged, or it may turn off after a while.

  1. Turn off the Charger.

After the battery has fully recharged, turn off the charger. Now time to detach the clamps. Do this in reverse order— remove the negative (black) clamp first, then the positive (red) clamp.

How Long Does It Take to Charge a Car Battery?

Charging a battery with a portable charger could take between a few minutes to a couple of hours, depending on the power of the charger and the battery’s situation. 

Try to let your battery charge to the fullest before driving it. Yes, a partially charged car battery will allow you to drive the car to your home (if it’s close), but you may need to start the process all over again if you don’t let it fully charge the first time around. If your battery is really old, it most likely won’t hold any charge no matter how long you leave it hooked up to a charger.


There you have it – recharging your car battery in four easy steps. If the battery doesn’t hold any charge, your last resort is to tow the car to a place that will evaluate and fix the problem. If that’s the case, you either have an old or weak battery or a deeper electrical issue, and you’ll need the help of a professional to solve it. Thankfully, it’s not too hard to find an auto parts store in most places.