Expert Advice | How to Charge a Car Battery – 2 Safe and Easy Methods

Here are two methods about how to charge a car battery. The first one requires a car battery charger. The second is less cheap and quite famous, yet you’ll need another car with a good battery. Whatever the method you'll use, there are some tips and tricks you need to know and be aware of. Still, the process itself is not rocket science.
How to charge a car battery
How to to charge a car battery? All what you need to know

I spent several hours researching and putting together simple and clear steps on how to charge a car battery. As per our mission and goal at Car Care Handy, I aim to cut through the jargon and help you make the right decisions for your car care and maintenance.

Safety Warning

Car battery charging – Safety warning

There are all sorts of dangerous risks linked to charging up a car’s dead battery. You could get shocked or touched by the battery acid. This is why you need to be very careful when getting a dead car battery to charge safely.

Before you start, you need to prepare for this potentially dangerous procedure. Before you even start with charging, you need to make sure your battery is safe to be charged.

If your car is emitting a strong stinky smell of something rotten, then chances are your battery is not safe to be charged. It might be leaking. Stay away from your car and call a professional to assist you.

If your battery is safe, then you can start with the charging. Sometimes, you’ll have to remove the battery completely from the vehicle and then recharge it. Some batteries can be easily removed. Some are not. You can even find your battery in the fender or the trunk, and sometimes even under the seat.

Make sure that you have with you the tools you’ll need. It’s always recommended to keep a pair of gloves around and some sort of eye protection. Before you put on your gloves and before you touch anything, make sure you’re not wearing any jewelry. It’s also advisable to remove any sort of loose clothing you have on. It might not seem like it, but it can cause a safety hazard.

It’s also very necessary to take a look at your manual. Instructions may differ from car to car. For example, if your car has a remote positive terminal, you can use it to charge up your battery safely.

Before connecting your charger, make sure it’s as far as it can get from your car. When you want to connect the cables, always use the red positive jumper cable first.

Keep your face away while connecting the clamps and make sure to never touch them while the battery is charging. [1, 2, 3]

Check Points

Whatever the below method you’ll use to charge your car battery, you may need these two checkpoints.

Cleaning The Battery Terminals

Cleaning the battery terminals

Clean the terminals well and make sure they’re ready for the wires. You can use a terminal cleaning brush. And to neutralize the battery acid, it’s recommended to use baking soda mixed with water.

Remember, you should be wearing gloves and eye protection. And don’t forget to consider all the safety points mentioned above.

You should never let the terminal acids or dusty powder touch any part of your bare skin. Wearing a mask is also preferable so you don’t accidentally inhale the acids.

Water Level

Car battery charging – Water level

If the battery has removable caps, what you need to do next is pry them off carefully. This is an important step, otherwise, the gases that emit from the charging won’t scatter away. 

You can locate these caps on the top of the battery or even under a yellow peelable strip, depending on your vehicle. Note that not all cars have removable caps.

Check the car’s water level. If the cells look low, you need to add distilled water only and make sure it’s within the battery limits.

Method #1: Using Car Battery Charger

Car battery charger

If you have a car battery charger in the trunk, or if you can get one, this method is for you. Follow these five steps and you’ll be done.

Step 1

Make sure both your car and your battery charger are off.

Step 2

Red cable: Connect the red positive cable on the charger to the positive terminal on your battery.

Black cable: don’t hook the black clamp to the negative post directly. In case your battery is leaking and you didn’t notice, this might be very dangerous. It can even lead to explosions. It’s recommended to connect the black negative clamp to your car’s chassis or another stable area on your car’s body.

Step 3

You need to set up the charger to the charge rate you want. Ideally, just adjust the volts and amps to the lowest rate. The slaw rate will make your battery take longer to charge, but it’s safer and more reliable. So if you’re looking for a speedy charge, you can just adjust the rate to a higher level. 

Make sure you keep in mind the instructions of the charger manual.

Step 4

Turn on the charger. According to the type of charger you’re using, you might need to plug it into a power supply. Usually, it’ll just work when you turn it on.

Make sure you set a timer for the charging. Not all types of chargers have an automatic stopping system that will immediately stop the charging once the battery is full.

Step 5

Now that you have a recharged battery, disconnect the charger. If you’re using a power source, unplug the charger.

Unhook the cables. Do the opposite of what you did in step 2. Disconnect the black one first and then the red.

Method #2: Using Another Car Battery (Jumpstart)

Car battery charging – Jumpstart

If you don’t have a car battery charger, this method is for you. This is where jumper cables come in handy. You might already be familiar with these cables. We’ll show you how to use them effectively to charge your car battery. Just follow these five steps.

Step 1

Since this method requires assistance from another car, you have to call a family member or a friend. Make sure to have the two cars parked facing each other and as close as possible.

Step 2

You need to make sure your car engine is off as well as all the lights and accessories including the radio. Otherwise, this can cause some unwanted damage to your battery.

Step 3

Red cable: attach the first clamp to the positive terminal on your battery, then attach the second clamp to your friend’s positive battery.

Black cable: attach the second clamp, related to the red cable, to the negative terminal of your friend’s battery, then attach the first clamp to the chassis or another stable area of your car.

Step 4

When both terminals are attached, start the engine of your friend’s car and then your own. Now, rev the engine of your friend’s car and let the two cars sit for a couple of minutes.

Step 5

Remove the cables. Do exactly the opposite of what you did in step 3. Disconnect the black negative first, then the red positive.

Black cable: disconnect the clamp from your battery, then the clamp from your friend’s car battery.

Red cable: disconnect the clamp from your friend’s car battery, then the clamp from your battery.


Car battery charging – FAQ

How long does it take to charge a car battery?

If you’re using method #1 described above, the length of the charge depends on the volts and amps you set it to. A low voltage and amperes will make your battery charge slower, and hence, the battery lasts longer.

If you’re using method #2, you may take a short ride after the jumpstart, and not turn off your car engine before 15 minutes.

What to do if a car battery doesn’t hold a charge?

If your car battery doesn’t hold a charge, no matter how long you leave it on the charge, it means that the cell is bad. It’s time to replace it. Go to the nearest professional and get your car a new battery!

Is it possible to charge a rRunning out of water car battery?

The short answer is yes, and you should consider refilling it with distilled water before putting it to charge. In such a case, your car battery may no longer hold a charge. It mainly depends on how long it’s been dry. You’ll have a clear answer after charging it.

The Bottom Line

A car’s battery can gradually drain out for multiple reasons. Prolonged parking for example, or forgetting your headlights on lead to serious loss of energy. It may even look in very good shape at times, which is why you should always be alert to the signs of wear it might give off.

Sometimes replacing the battery isn’t the optimal choice. The best option is to charge your car battery. As described and explained throughout this article, you can choose one of the two methods on how to charge a car battery [4, 5].

Do not hesitate to let a professional assist you if you feel not comfortable with the process.

Do you want to learn more about disconnecting car batteries? Check out our guide on how to disconnect car battery.