Car batteries retain their charge due to the extra power from the car engine. Most can last at least five years without needing to be replaced or recharged. However, even the best car batteries will eventually run out of power or lose their charge prematurely if you leave the lights on for too long. This can be a huge inconvenience. Fortunately, the car battery can be recharged without much effort and with few tools and mechanical experience.
Method 1 of 4: Prepare to charge the battery
Step 1. Set a suitable gear
Safety is essential every time you work on your vehicle. Start by wearing goggles to protect your eyes from any material that might fall under the hood of the car, sparks, or battery fluid in case the battery is in danger. You can also wear gloves. Make sure the area where you work is well ventilated and light enough to allow you to see what you are working on.
- Gloves are not necessary, but they can protect your hands from minor punctures or cuts while working on your vehicle.
- Make sure there are no children in the area while working on a vehicle battery, as sparks could fly if the positive and negative cables come into contact.
Step 2. Determine what type of battery you have
To properly charge the battery, you first have to identify the type of battery you have. Usually this information is written somewhere on the battery. However, you may need to go to the manufacturer's website if the label is badly worn and unreadable, or just doesn't have a label. You can also look for the battery's voltage on the battery label, or check your vehicle's manual. Battery types include:
- Batteries with wet cells can be helpful, which means you have to do things to improve your battery's charge and life.
- Valve Regulated Lead Acid (VRLA) batteries are completely sealed and maintenance free. These batteries come as gel cell or absorbed crystalline cell batteries, and are less common in automobiles, unless they were purchased after being modified.
Step 3. Get a car battery charger
Get a suitable charger for your battery and purposes. Most chargers will work for all types of batteries except gel cell batteries. There are fast chargers that can charge your battery instantly and can even give it a boost. Also, "trickle" chargers provide a slow but long-lasting charge. Many newer chargers come with a microprocessor to control how much the battery has been charged. These digital chargers will automatically stop when the battery is fully charged. Older or simpler chargers have to be stopped manually to avoid the danger of overcharging, and should not be left unattended for an extended period while connected.
- Read the charger's instruction manual to make sure you use it properly.
- Even modern digital chargers need to be monitored while charging to make sure they work well and stop before overcharging the battery.
Step 4. Disconnect and remove your vehicle's battery if necessary
It is important to disconnect the battery before carrying out any repairs or maintenance on your vehicle. Most of the time you will have to charge the battery without removing it from the car, but if reaching for the battery, connecting the cables in the engine compartment, or finding the battery trunk is difficult, fully house the car battery while charging it.
- If you are unsure of the location of the battery, check your vehicle's owner's manual. Some vehicles have the battery in the trunk, but most have it under the hood.
- First, disconnect the negative terminals; then the positives when removing the battery.
Step 5. Clean the battery terminals
Any dirt or soot on the battery terminals can prevent the cables from making a good connection to the battery. It is important to clean the terminals thoroughly. Use baking soda and a wet cloth or sandpaper to remove any dirt or rust. Make sure the terminals are exposed to metal before proceeding to the next step to ensure a good charge.
- Sometimes you may notice that the battery has a solid charge but dirty terminals that prevent electricity from flowing.
- Do not touch the terminals with bare hands, especially if there is white powder on them. This powder is usually dry sulfuric acid and can burn your skin if it comes in contact with it.
Method 2 of 4: Use a fast or slow charger
Step 1. Place the charger on a stable surface
Never place the battery charger directly on the battery while connecting to the negative and positive terminals, which will damage the battery and the charger, causing a possible fire. Instead, place the charger on a stable surface, away from the battery and cables. Before connecting the charger to the switch, make sure the area is well ventilated by opening the garage door and windows if you are in an enclosed area.
- Secure the surface where you place the charger, on a stable support, to prevent it from falling and disconnecting from the battery.
- Use the longest cables possible to separate the battery from the charger.
Step 2. Connect the charger to the battery
Attach the black lead from the charger with the negative sign (-) to the negative terminal on the battery that is marked with the same symbol. Then, connect the red wire with the positive sign (+) to the positive terminal of the battery with the corresponding symbol. Be sure to check the connections before plugging in or turning on the charger, as mixing the positive and negative terminals can cause battery damage or even fire.
- Some cars may have the positive terminal label with the initials POS, instead of the positive sign (+); and NEG, instead of the negative sign (-).
- Make sure the cables are firmly attached to allow electricity to flow from the charger to the battery.
Step 3. Set the charger
Digital chargers can indicate the existing voltage in the battery and allow you to set the final voltage level. While older models simply allow on and off settings. The fast chargers will also allow you to choose the speed to charge the battery 8 usually, represented with the image of a tortoise for slow charges and that of a hare for fast ones). A quick charger is good for a car battery that has recently stopped working as a result of leaving the lights on, or something else; Whereas the battery that has stopped working for a little longer sometimes needs the trickle charge method before using it again.
- If you can set the voltage at which the charger will stop, set it to the voltage specified on the battery or to what is described in the vehicle's user manual.
- Never set the charger to the fastest charge if you are not going to monitor the vehicle.
- You can leave the battery charging slowly overnight for a full charge, if the battery has been dead for a little longer.
Step 4. Check the battery
After letting the battery charge, make sure it works. Some digital chargers will give you a reading that will tell you if the battery is adequately charged, or if the battery will need to be replaced. This is usually indicated by a percentage such as "100%" when the battery is 100% charged. You can also use a voltmeter to measure the voltage of your battery when it is disconnected from the charger, by touching the positive and negative leads of the voltmeter to the respective battery terminals. If the battery is still in the car, the easiest way to check it may be to plug it in again and try to start the car.
- If the voltmeter reads the proper number of volts for the battery, the charger indicates that it is okay, or the vehicle starts the battery that is sufficiently charged.
- If the voltmeter or charger indicates that the battery is bad or the vehicle will not start, there may be other problems or the battery may need to be replaced.
Method 3 of 4: Charge Your Battery
Step 1. Park a running car so that the battery faces the car you are driving
Powering a vehicle means using the electrical system or another running vehicle to charge the battery in yours, enough to let it start and charge automatically. Before parking a running car, be sure to locate the battery in both vehicles, as the batteries for some vehicles are in the trunk. When you have located the batteries in both vehicles, bring both vehicles closer together so that the cables connect both batteries.
- If the battery is in the trunk of one of the vehicles, back up so the cables can reach each other.
- Set the parking brake on both vehicles to make sure they don't move during the loading process.
Step 2. Use jumper cables to connect the two batteries
Remember that when you have connected the jumper cables to a battery, touching the positive and negative ends on the other side of the cables will produce sparks that can be dangerous. With both cars disconnected, connect the jumper wire to the positive terminal of the dead battery, then to the positive terminal of the running battery. Make sure not to let the negative wires hang inside the engine compartment, where they can come into contact with metal and cause a short circuit. Next, connect the negative cable to the negative terminal of the dead battery, followed by the negative cable to the appropriate terminal of the working battery.
- You need to clean all the terminals on both batteries to ensure a stable connection.
- Make sure to connect the positive ends to the positive terminals and the negative wires to the negative terminals. Mixing them may cause damage or fire.
Step 3. Begin to start the car
With the cables securely connected, start the vehicle, so that its electrical system begins to charge the dead battery. Do not take the vehicle out of park or neutral mode during the charging process. Let the vehicle start for a few minutes before attempting to start the other vehicle.
- After a minute or two, try to start the dead car. If the battery has recently been discharged, it should start immediately.
- If it doesn't start after a minute or two, let it charge for a little longer. If the battery has been dead for some time, it may take a little longer for it to start.
Step 4. Disconnect the cables and let the vehicle start
When the vehicle starts, you can disconnect the jumper cables from each vehicle. Let the vehicle with the dead battery continue cranking for a little longer. You may have charged the battery enough to start the vehicle, but if you turn it off immediately, there may not be enough electricity to start it again. By letting it start, you give your vehicle's alternator a chance to charge the battery for the rest of the ride.
- If the car stops once more after being disconnected from the other car, check the battery to make sure it is connected securely.
- If the vehicle is running well, run it for a short ride while the battery charges before turning it off again.
Method 4 of 4: Resolve Battery Problems
Step 1. Check the battery at an auto parts store
If you've charged the battery with a charger or other vehicle, but your vehicle still won't work, remove the battery (if it hasn't already) and take it to a nearby auto parts store. There, they can charge the battery and check if it works well, if it needs maintenance or replacement. If your car battery is a valve regulated lead acid (VRLA) battery or a maintenance-free wet cell battery, you will need to replace it without it being unable to charge.
- If the battery is bad, you will have to buy a replacement.
- If the battery is fully charged and working fine but your car won't start, check the battery cables to make sure they are not broken and connect them firmly to the battery.
Step 2. Test the alternator
A faulty alternator can prevent your vehicle from charging enough to the battery to start the car again, it can even fail by not producing enough electricity to keep the car running. You can check to see if there is a problem with the alternator when starting the car, then disconnect the positive battery terminal. A properly functioning alternator will produce enough electricity to keep the vehicle running without the battery, but if the vehicle shuts down, the alternator will likely need to be replaced.
- Sometimes you can tell if there is a problem with your alternator by looking at the internal lights. If the light is brighter when you step on the gas, then it dims again when you take your foot out, it could be that the alternator is bad.
- If you remove the alternator from your vehicle, many auto parts stores can test it to make sure of the problem before getting a replacement.
Step 3. Hear a clicking sound
If the car won't start, but makes a clicking sound when you test it, there probably isn't enough electricity in the battery to start the vehicle. It may be because it did not charge properly, or the battery is too drained to charge properly. Try driving the car again or remove the battery and test it.
- Make sure to connect the battery correctly when charging; otherwise, the battery will not be able to start the car.
- The clicking sound indicates that there is some electricity in the battery, but not enough to start the engine.
Step 4. See if the vehicle stops
If the vehicle starts after charging the battery, but stops shortly after, it may be due to the alternator. If it starts up again or continues to start and stop, the problem is not electrical. It may be a problem with the fuel or air supply.
- Your vehicle needs air, fuel, and electricity to function properly.
- If this happens, you will likely need to take the car to a mechanic to identify the problem.
WikiHow Video: How to Recharge Your Car Battery