The battery is one of the most important parts of the car. Mainly, because it is in charge of sending all the energy necessary for the entire car to work properly: everything from the electrical part to starting the engine needs it. This is why you can’t start your car when the battery has run down.
Leaving the radio or a headlight on by accident are some of the most common reasons for a dead battery. However, you do not need to call a tow truck and take it to the workshop to charge the car battery. There are some easy ways to charge it, without spending a lot of money.
Charge fully discharged car battery
One of the signs that your car battery has completely discharged is that your car won’t start. Of course, there may be other reasons why your car won’t start: for example, an alternator has failed or the injectors are malfunctioning because of something that’s hampering them. So if you recharge the battery, the car won’t start anyway.
But if you have verified that it is the car battery that has been completely discharged, there are a few ways you can recharge it:
- You will need the battery from another car. You can use any car: that of your husband or wife, another family member, friend or neighbor. The idea is to use another car’s well-charged battery to power your vehicle.
- Use a set of clamp cables. The cables with clamps will allow you to transmit electricity from one battery to the other. Of course, verify that the other cable is the same thickness as yours. Otherwise, it could not work.
- You can also use a battery charger to charge your car battery . If charging it with another car’s battery has not worked for you, use a battery charger.
- Use your car for a long time . If the battery has not been completely discharged and if you have already managed to recharge it, the ideal is to drive for a long period of time so that the alternators finish charging it.
However, no matter which of these methods you use, there are a few things you need to be aware of to prevent damage to your battery, charger, or car.
- Identifies the location of the battery . Depending on its location, the difficulty of accessing it and recharging it will be determined. Most of the batteries are located under the hood. Some are in the trunk and very few are under the back seat.
- Recognizes the positive and negative port of the battery . It is vital to avoid any short circuit. On the battery it is indicated to which port each entry corresponds. The negative has the marks: “Pos”, “P” or “+”. And the negative has “N”, “NEG” or just “-“. Another way to identify them is that the wire that is usually in the positive port is red, while the negative is black.
Having understood this, let us see the different methods to charge the car battery.

How to charge car battery with charger?
Charging your car battery with a charger is not a difficult task. However, they do need to take into account some steps to do it properly.
- Clean the battery terminals or posts . Especially if they are too dirty. You can apply baking soda with water using a toothbrush (preferably an old one) to remove the sulfuric acid. Wash your hands after this process and touch nothing.
- Do not place the charger very close to the battery . Try to be as far away from the battery as possible. Do not place the battery above or below the charger.
- Take the clips from the charger and plug them into their proper ports. With the charger turned off, first connect the positive clamp to the positive port. And only then do the same with the negative.
- Connect the charger to a power source. Battery chargers typically have a 3-prong plug. Connect directly to the outlet and if possible do not use adapters. And in case you use it, you have to choose the ones that also have a ground connection, that is, with 3 pins.
- The charger must be connected until the battery is fully charged. How to know if the battery is fully charged? You can find out through the manufacturer’s manual. Another easier way is to watch the charger indicator, which will drop as the battery charges.
Once the car battery is charged you should also be a bit meticulous when disconnecting it from the charger to avoid any damage. Follow the next steps:
- Unplug the charger. The first thing you should do when the battery is charged is to unplug the charger. Do not disconnect anything else without first disconnecting the battery, it could cause sparks that could ignite the gases that have been emitted from the battery during charging.
- Disconnect the clamp that is on the negative port. Just as it is the last to connect, it will be the first to disconnect. Later…
- Disconnect the clamp from the positive port. Disconnect the clamp on the positive battery port clamp. Some chargers have a feature that allows you to leave the positive connected to start the engine. If your charger doesn’t have it, unplug it.
- Put the battery in its place and reconnect its cables. Place the battery exactly where you found it (in case you removed it). Then plug the positive clamp and negative clamp into their corresponding ports.
How to charge car battery with clamps?
Another simple way is to charge the car battery is by using the battery of another vehicle. Get a car that has a fully charged battery. You will also need a set of clamps that have the same voltage as the battery.
Then place the two cars close enough so that both clamps can make a connection on both sides. However, the cars must be far enough apart that they do not make any contact. Once this is done, we will proceed with the following steps:
- Connect the clamps first to the car that has a charged battery. First, the clamps are connected to the car that has a charged battery, not the other way around. Understanding this, the clamps are connected following this order:
- Positives come first, then negatives. Connect the positive on the car that gives the power, then the positive on the car that has the dead battery. Then connect the negative in the car that does have power. Before connecting the last negative in the car with discharged battery, you must start the car that has current. Otherwise, both vehicles could run out of charge.
- Accelerate the car that has current . Once everything is connected, accelerate the car and leave it like that for a few minutes until the battery is charged.
Once the battery is charged, you simply reverse the order in which you connected everything. Disconnect the negative of the car that was discharged and then the one of the current donor. Then the positive of your car and finally the one that was loaded.

This trick will not fully charge your car battery. To fill its entire load you must complement with the following trick:
Charge car battery while driving
Once you have charged the battery of your car with the method, you must circulate with it for at least 20 or 30 minutes so that the battery is charged. If you want it to reach its usual charge, you will have to drive from 45 minutes to more than 2 hours .
Circulating helps the alternator transform mechanical energy into electrical energy. In other words, it converts the energy produced by the car when it is running into electrical energy and thus charges the battery. The charging time may vary depending on the charging capacity of the alternator.
Frequently asked questions about charging the car battery
Despite all this explanation, it is normal that you still have some doubts. These are the most frequently asked questions about car battery charging.
Can a battery put in the car be charged?
Of course. In fact, in most cases you can charge the car battery without removing it. Especially if there is an accessible power point on top of the battery and the charge rate is 3-4 amps.
How long does it take to charge a car battery?
Battery charge time will depend on a number of factors, from the size of the battery, the volts it uses, and how discharged it is to the method you use to charge it.
The battery takes current from another car through the clamps only in a few minutes. But you will have to drive from 45 minutes to more than 2 hours to fully recharge the battery and better if it is on a highway or road so that it does not turn off when braking and then have difficulty turning it on.
When driving, the car’s alternator can deliver up to 45 to 60 Ah to the battery. Which makes the loading time a little faster. But it will also depend on the capacity of the alternator.
How long does it take to charge a car battery with a charger?
If you use a charger, everything will depend on the capacity of the charger, the battery and its level of discharge. For example, a fully discharged 45 AH battery with a 10 AH charger could take up to approximately 4-5 hours . Other smaller capacity batteries may only take 40-45 minutes .