How to Charge a Car Battery
Nothing is more frustrating than getting in your car in the morning and discovering you have a dead battery. You turn the key and hear nothing but a sad, clicking sound.
The good news is, learning how to charge a car battery is not hard.
However, the process must be done correctly. The task can be dangerous if done in a haphazard fashion. You risk getting shocked and causing harm to yourself and your vehicle if you don’t pay attention to the correct procedures.
There are three ways to charge your battery, with a charger when your battery is still in the car, with a charger with the battery out of the car, and jumping the battery with another car. We’ll talk about each method.
Preparing to charge with a charger
Be sure you’re in a well-ventilated space.
Most batteries are easy to locate but a few are placed in odd locations. Refer to your owner’s manual if the battery is not easily accessible.
Make sure all lights and accessories in your car, even interior lights, are off.
Wearing safety goggles is always a good idea to protect from possible sparks or corrosion.
Add distilled water to the cells of the battery if needed. Most newer batteries are maintenance free and don’t require this step.
Clean the terminals with a brush cleaner. You can use a mixture of baking soda and water which will neutralize the acid.
NEVER touch your fingers to your face or eyes while cleaning the terminals. When you are done, immediately wash your hands.
Charging the battery while it’s still in the car
If you’ve done all the above steps you’re ready to charge your battery.
Move the charger as far from the car as the cables will allow. The charger should be sitting on wood or cardboard and not cement.
Note: It’s always best to read the directions that come with your particular charger, your battery, and your car.
Check to make sure the charger is in the off position. Some don’t have on/off switches so make sure it’s not plugged in yet.
Hook up the cables – Connect the red, positive (+) cable from the charger to the positive post in the batter. Then connect negative (-) to negative.
Double check to make sure you’ve connected correctly. The negative terminal is usually smaller.
Set the charger rate based on what’s suggested for your battery in your owner’s manual. If you’re not sure, start with the lowest rate.
If the charger has a volt setting then set it to 12. (The majority of car batteries are 12 volt but double check to make sure that’s what yours is.)
Charge for the suggested length of time. This can take anywhere from six to ten hours depending upon the amps of the charger. A slow charge will take longer but also last longer than a short, burst charge.
(Some new chargers will automatically shut off when your battery is fully charged but others need to be turned off to keep from overcharging. Read the directions!)
Chargers with a L.E.D. readout will show you what percentage of the battery has charged as it’s charging.
When done, turn the charger off and unplug from the electric outlet.
Remove the cables in reverse order.
Any sparks can cause the battery to explode so be extremely careful to not let clips touch each other or the hood or other parts of the car.
Charging the battery out of the car
Unscrew the post for the negative (grounded post) first. This is usually the black cable but check for the negative mark. Then disconnect the positive post.
Unscrew the battery from the bracket that holds it in place.
Carefully remove the battery and set near (never on) the charger.
Continue hooking up the battery to the charger per the above directions. Positive first and then negative.
After the battery is charged return to the car and make sure it is properly secured to the bracket that holds it in place and the terminals are securely reattached.
Some people feel that charging a battery outside the car is safer so if there are any problems it won’t affect other parts of the engine such as the alternator.
However, leaving the battery out for too long can cause problems with electrical systems so you’ll have to decide what is best for your car. Refer to the owner’s manual.
Jump starting your battery from another car
If possible, place cars about 20 inches apart – facing each other. The cars should never be touching.
Both cars should be in park or in neutral for a manual transmission. Parking brakes should also be set. The cars should be off and have keys removed. All lights and accessories should be turned off.
Open both hoods.
Locate the batteries and terminals in each car. It’s is crucial that you can see which posts are positive (+) and which are negative (-). You may need to clean the terminals with a wire brush.
First, attach the positive (usually red) cable to the dead battery. Make sure the clamp is secure so you’ll get a good connection.
Connect the other end of the red cable to positive terminal of the car with the live battery.
Connect the black cable to the live battery’s negative terminal.
Take the other end of the black cable and attach it to the negative cable of car with the dead battery. (This cable can be simply attached to the engine block).
Start the car with the live battery and let it run for several minutes.
Then try to start the car with the dead battery. If it won’t start, then continue to charge for a few more minutes.
Disconnect the cables starting with the negative first. NEVER let the clamps on the cables touch.
Drive the car for awhile to build up the charge.
If the battery doesn’t hold the charge, or doesn’t hold it for long, you’ll probably need to replace with a new battery as quickly as possible. An auto parts store will usually test your battery for you at no charge.
If the battery tests okay then you need to take the car to a mechanic to check out other problems such as the alternator.
Do it yourself car maintenance is not hard. But you do need to spend some learning the correct procedures to protect you and your car from harm.