Posted by To charge a car battery, first, remove the negative and then the positive terminal of the car battery. Now attach the charger’s red clamp to the positive terminal and the black clamp to the negative terminal of the battery. Switch on your charger to charge the car battery.
Ensuring your car is ready for driving in any situation starts with a well-charged battery. So you need to know the basics of how to charge a car battery. This will help you deal with any problem you might ever face.
Whether it’s a completely dead battery or one that needs a bit of charge for optimal performance. Mastering the art of charging a car battery is essential for every driver.
The process of charging a car battery can be divided into three stages. The first step is to pre-checking the car battery. The second step is about how to charge a car battery. The third step is post-checking or inspecting the car battery.
Pre-checking the car battery involves checking for any visible damages or cleaning needed. If there is visible damage on the battery terminals or they are not clean.
Post-checking involves checking the car battery volts, amps, and watts with the engine off and on condition.
Tools needed
- Battery Charger (complete set with wires)
- Safety Gloves
- Safety Glasses
- Adjustable wrench or spanner set
- Wire brush
- Battery Water / Distilled Water
- Funnel
- Multimeter
How to Charge a Car Battery
Following are the steps involved in a proper and safe procedure of charging a car battery:
- Make sure that your car ignition is off and your car is horizontal with the parking brake engaged.
- Wear all personal protective equipment.
- Locate the battery and use either an adjustable wrench or spanner set to remove the terminals of the battery.
- Always remove the negative terminal of the battery first and isolate it using a cloth.
- Remove the positive terminal of the battery and isolate it too.
- Use a wire brush to clean the battery terminals. Remember not to touch both terminals at the same time.
- If you have a non-sealed battery, check the water level inside the battery. Do a refill if needed using a funnel and distilled water.
- Now take the red clamp of the charger and attach it to the positive terminal of the battery. The positive terminal will have a “+” sign on the battery.
- Attach the black clamp of the charger to the negative terminal of the battery. The negative terminal has a “-” sign on the battery.
- Depending on the charger type, you might need to set the voltage and amperage for the battery charging.
- Now connect the charger power cable to your home or workshop power outlet.
- Switch on the charger, and your battery charging process is on.
- After charging, remove the negative clamp of the battery charger first, and then remove the positive clamp.
- Take a multimeter, and switch it to the voltage. Connect the red probe to the positive terminal and the black probe to the negative terminal of the battery. A good fully charged battery should show a voltage rating of 12.6 volts.
- Now connect your battery with your car. Remember to connect the positive terminal first and then connect the negative term.
How long does it take to charge a car battery?
It will take 6 to 12 hours to charge a car battery, depending on the battery ampere-hours (Ah) and the charger ampere capacity. A battery charger that can deliver 4 amperes per hour will charge a 48 ampere-hour (Ah) car battery in 12 hours (it’s 48/4 = 12).
Similarly, a battery charger with an 8 ampere per hour capacity will charge a 48 ampere battery in 4 hours. Most battery chargers deliver amperes between 4 to 8 amps. Remember charging at a faster rate can affect your battery health.
There is no auto-disconnecting feature in most car battery chargers, so you have to manually disconnect the charger.
How long to leave a car running to charge the battery?
Theoretically, it will take about one and a half hours, that is 90 minutes, to charge a car battery using its alternator. It’s a theoretical calculation, and actual time may vary depending on the battery state and alternator efficiency.
At an idle state, a car alternator can produce 40 amps, and at full throttle, it can produce about 120 amps. These amperes are equally divided into different electronic sections of the car as alternators have to provide electric power to all vehicle electronics.
How to charge a dead car battery?
To charge a dead car battery, first, remove the negative and then the positive terminal of the car battery. Now attach the charger’s red clamp to the positive terminal and the black clamp to the negative terminal of the battery. Switch on your charger to charge the car battery.
If your car battery is dead because it has been discharged fully, then you can recharge a dead battery using the standard method mentioned above. If your car battery is dead because of a damaged cell, then it cannot be recharged using any technique.
You can check a car battery by using a multimeter. Switch it to a voltmeter and check the walls of the car battery.
If the voltmeter gives anything above 11.8 volts, then your battery is still good and needs to be recharged. Anything above 11.6 or below indicates a weak cell and so a need to change a car battery.
How to charge a car battery without a charger?
You will need another car and jumper cables to charge a car battery without a charger. Following is the complete procedure on how to charge a car without a charger.
The same procedure can also be used for how to charge a car battery with another car. Also, on how to charge a car battery with jumper cables.
- Park both cars facing each other on a horizontal surface. Both cars are in the Park position with the ignition turned off.
- Take the red jumper cable first. Connect one clamp with the positive terminal of the dead battery.
- Connect the other red clamp with the positive terminal of the charged battery.
- Take the black jumper cable and connect one clamp with the negative terminal of the charged battery.
- Connect the other clamp of the black jump cable with any unpainted metal surface of the car with a dead battery.
- Start the car that has the charged battery.
- This will start charging the dead battery on the other car.
- Keep the car running to put some charge on the dead battery.
- Start the car with the dead battery. If successful, let both cars run for a few minutes.
- Remove the jumper cables in reverse order.
- First, remove the black clamp from the car with a previously dead battery.
- Then remove the black clamp from the car with the previously fully charged battery.
- Then remove the red clamp from the car with the previously fully charged battery.
- And then at last remove the red clamp from the car with a previously dead battery.
How to charge a car battery at home
You will either need a car battery charger or a set of jumper cables and a car with a charged battery. Then you can adopt the process of charging the car using a car battery charger. You can also jump-start your dead car battery and then let the car alternator charge the cell battery.
Remember these procedures are only recommended when you have all the necessary personal protective equipment and standard tools to perform the charging process.