If your car battery has been connected to a charge maintainer over the winter or you've had to disconnect it for other repairs, reinstalling it is a fairly simple process. All you will need is a few simple hand tools and other supplies that you probably have around the house. It is important not only to connect the battery, but also to make sure the connections are clean and the battery is secure.
Steps
Part 1 of 3: Clean and Inspect the Battery and Its Connections
Step 1. Put on protective glasses and gloves
Protecting your eyes is very important when reinstalling the battery. If the positive and negative cables are accidentally mixed, for example, the battery could overheat and "explode", splashing the water or chemicals stored in it.
- Latex gloves will protect your hands if the battery leaks or explodes, but mechanic gloves also offer protection against scratches and punctures.
- Safety glasses offer the most protection, but traditional goggles are fine too.
Step 2. Make sure the keys are out of the ignition
It is important that none of the vehicle's electronic components are "on" when you reconnect battery power, otherwise the power surge could cause damage. If the keys are in the vehicle, turn off the ignition and remove them for safety.
In some vehicles, just having the key inserted into the ignition activates the door system
Step 3. Clean the battery posts with water and baking soda
Use a wire brush to remove any corrosion or build-up on the battery posts before putting it back in the car. Add 1 tablespoon of baking soda to 2 cups (500 ml) of water to create a cleaning solution to help remove corrosion.
- The baking soda and water mixture is abrasive enough to scrape off rust or old oil.
- If you don't have baking soda, you can use 100-grit sandpaper to achieve the same result.
- Use a damp cloth to wipe up the baking soda mixture when you're done.
Step 4. Rub off any rust and debris from the battery cable tips
Use the same mixture and the same wire brush used on the terminals to clean the ends of the car wires as well. There has to be a good metal-to-metal connection for current to flow from the battery to the car.
- The exterior of cable connectors is usually painted. It's okay to leave the paint intact, just make sure the inside of the fitting is clean and free of any residue.
- Use a damp cloth to wipe up the baking soda mixture when you're done.
Step 5. Apply an anti-corrosion material to the terminals and the ends of the cables
You can find a variety of electrically conductive anti-corrosion creams or sprays at any auto parts store. Choose a product and apply it to the positive (+) and negative (-) terminals of the battery, as well as to the inside of the connectors of the car cables.
- These products are also sometimes called battery terminal protectors.
- Spray or apply cream to connectors and terminals generously, then wipe off excess.
Step 6. Inspect the cables for cracks or damage
There are two cables that connect to the battery. The connector at the end of the positive cable is usually painted red or has a red plastic clip attached to it. This reaches the engine alternator. The second wire is a ground wire, which connects the negative terminal of the battery to the body of the car. Look at both cables closely for signs of damage or cracks.
If the cable jacket is cracked or the cable itself shows signs of wear or damage. It will need to be replaced
Part 2 of 3: Securing the Battery in Place
Step 1. Replace any cables that you notice cracked or damaged
To replace the positive cable, use an appropriately sized ratchet wrench to remove the nut that holds it to the top of the alternator. Slide the wire end loop out of the nut, then slide the replacement wire loop into place and secure with the nut. The negative cable can be replaced in the same way, but by removing the screw that holds the cable to the body of the car, then putting the new cable in place and retightening the screw.
- You can buy both cables at your local auto parts store.
- If neither cable is damaged, you can skip this step.
Step 2. Find the battery tray
In most vehicles, the battery tray is located in the front of the engine compartment on one side (behind one of the headlights). However, many newer vehicles place the battery in the trunk or even in the cabin of the vehicle, for better weight distribution.
If you're having trouble finding where to install the battery, you can refer to your vehicle's owner's manual or the manufacturer's website for guidance
Step 3. Position the battery correctly by orienting the wires to the terminals
Most car batteries have their terminals near one edge of the battery. The positive cable will come from one side of the engine compartment and the negative cable will come from the other. Position the battery so that the positive (+) terminal is on the same side as the positive cable and the negative (-) is on the same side as its corresponding cable.
- The positive battery terminal will be marked with a "+" sign.
- The negative terminal will be labeled with the "-" sign.
Step 4. Use both hands to lower the battery into position
Be careful, batteries can weigh 20 kg (44 pounds) or more. Grab the battery by the sides as you lower it into the tray, being careful not to pinch your fingers while doing so.
- Make sure there is nothing on the tray before lowering the battery.
- If necessary, move the battery cables aside while you put the battery in the car to prevent them from getting in the way.
Step 5. Install the battery holder
Some car batteries use a metal hook that you can loosen and tighten by hand, while others may use a metal or rubber strap. Find the strap or hook on the vehicle and use it to secure the battery in place.
- The straps must be placed over the battery and then secured on the other side, often using a screw that can be tightened with a ratchet wrench.
- Hooks can sometimes be turned by hand or with pliers, but some vehicles have a screw that is tightened to move the hook.
- If you're not sure how to fix the battery, check your vehicle-specific repair manual or the manufacturer's website for more information.
Part 3 of 3: Connecting the Battery Terminals
Step 1. Slide the positive cable onto the positive battery terminal
The positive wire will come from the alternator. Press the connector into the terminal by hand until it is flat against the battery.
If that connector does not slide over the post, use a wrench or ratchet to loosen the connector screw, then try again
Step 2. Use a wrench to tighten the wire on the post
Once the positive wire is in the terminal, it must be tightened to ensure that it cannot vibrate out while driving. Use a ratchet or wrench to turn the connector screw clockwise until snug.
- On many batteries, it is easier to use a wrench than a ratchet, but either will work.
- Try to move the terminal wire a little by hand to make sure it is secure. If it does move, tighten the connector more.
Step 3. Connect the negative cable to the negative terminal and tighten it as well
The negative cable must be installed as the positive one. Press it towards the terminal post by hand and then tighten it with a wrench.
- If any of the cables do not reach the proper terminal, it means that the battery was not oriented correctly when you lowered it into the tray.
- Move the negative terminal connection by hand and tighten it a bit more if there is any movement.
Step 4. Insert the key into the ignition and start the car
With the battery connected, the dome light should come on when the driver's side door is opened. Insert the key into the ignition and turn it to start the vehicle and make sure the battery is connected properly.
- If the vehicle won't start, check the connections at the battery as well as at the alternator and where the negative cable makes contact with the body. If they are all good, try again.
- If it still won't start, the battery itself may be dead. If so, try pulling it off with tweezers.
Warnings
- Always wear eye protection when working on the car battery, just in case it explodes.
- Be very careful not to confuse the positive and negative battery wiring, or the battery could overheat, explode, or catch fire.