How to charge a car battery: step-by-step guide & tips


Posted by: Juliet Onyeachonam

Share this post:

Latest news articles

Charging a car battery is a common practice every driver should know. This concise guide describes how to charge a car battery by yourself at home as well as gives you some tips during the process.

Charging a car battery is a task every driver must perform at some point in the life time of their vehicle. However, before you perform this unavoidable task, you should know that how to charge a car battery is more than just fixing up the charger to the battery terminals. For you to successfully charge your car battery, you should know which of the battery terminals to disconnect first and which battery terminal to fix the charger unto first before the other.

Check the tips below by Naijauto experts to master the process!

1. What to prepare before charging a car battery

Before charging a car battery, you need the right set of tools to be able to perform a successful battery charge. While the position of most car batteries is easily located, some are located under fenders or trunks depending on the make and model of the car.


This is where Toyota car battery is often located

Moreover, it is possible to get shocked if the battery has some charge in it if you do not know what you are doing. That is why it is important that you should read and follow this guide on how to charge a car battery.

>>> Some facts about car battery you can check: Different types of chemicals in your car battery and their functions

2. How to jump a car battery

Before proceeding with dismantling the battery, be sure you have turned off all car accessories such as lights, radio, A.C etc. Making sure all accessories are turned off is actually a very important step because failure to do so could cause the battery to undergo something called arcing - some sort of luminous electrical discharge between the terminals.

The right thing to do when you get to the battery is to disconnect the cable of the negative terminal first. This negative cable is known as the ground cable and is usually black in colour, although the colour could vary on rare occasions. For such a case, the easiest way to find out which cable is negative and which is positive is to look at the top of the battery. The negative or ground cable will bear a negative (-) sign while the positive or power cable will bear a positive (+) sign.


The right thing to do when dismantling the battery is to disconnect the cable of the negative terminal first

If you notice a lot of acid build up on the battery terminals, you can wash it off with a mixture of water and baking soda using a terminal cleaning brush, an old toothbrush can be used to improvise. Remember to wear eye protection and a mask to avoid contact with your eyes, nose and mouth.

If your battery is not a maintenance-free type, you should be able to pry open the battery caps to check the level of water in the cells. If the levels are low, you should fill them up with distilled water. Although most batteries these days will not require the above step as they are maintenance free and cannot be opened.

>>> Regular check on car battery can prevent serious problems: Car battery – How you can safely check and clean it

3. How to fix car battery charger

Carefully follow the following steps to hook up the battery charger unto the battery terminals for charging.

With the charger turned off:

  • Connect the positive cable of the charger to the positive terminal of the battery
  • Connect the negative cable of the charger to the negative terminal of the battery
  • Set the charge rate of the charger. The slowest charge rate is best
  • Switch on the charger and set the timer


Connect the positive cable of the charger to the positive terminal of the battery and vice-versa

After the battery is fully charged, turn off the charger then remove the positive cable of the charger first before removing the negative cable.

4. How long should you charge a car battery?

It will take approximately 12 hours to charge a battery with voltage below 11.85 at a charge rate of 5-amp. In like manner, it will take about 6 hours to charge the same battery at a charge rate of 10-amp.

Now that you know how to charge a car battery, you should also know that a battery whose cell has gone bad cannot hold any charge and would need to be replaced entirely.

>>> Other useful car maintenance tips and safe driving advice are available on!

Juliet Onyeachonam

Juliet Onyeachonam

Car maintenance

Juliet Onyeachonam is an enthusiastic car nut which is why she has turned that passion into a fantastic job by becoming a car blogger on Juliet's blogs are a wealthy resource for information on car maintenance, driving tips and also how things pertaining to cars work.

Additionally, because of her passion for the entertainment industry, Juliet does not write only hardcore but also entertaining articles about cars.

See more