How To Charge Your Car Battery With A Charger

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A charging device for your car battery is quite cheap but very useful device that will help you charge the battery. The question we want to know the answer for is how does a charging device charge a car battery?

  battery car charger how to use

Actually, everything is quite simple. A charging device for car battery uses electricity from a corresponding power source – a socket to charge your car battery. There is one negative and one positive output that are connected to the corresponding battery terminals. That’s it! Your car battery is being charged. An average car battery has the capacity of, approximately, 48 A. hour. This means that a fully charged car battery provides 1 ampere of current within 48 hours, 2 amperes within 24 hours, 8 amperes within 6 hours etc. The function of a charging device is to transfer these amperes for storage in a car battery. Then, they will be spent on the functioning of a car’s devices. As a rule, a charging device is necessary when there are 2 amperes left in a car battery. Consequently, a car battery can be completely charged with 48 amperes within 24 hours. However, there is a variety of charging devices that allow you to change the speed of charging. There are charging devices with the speed of charging from 2 to 10 amperes available. The higher is the speed, the faster will a car battery be charged. Still, the fact is that fast charging is, as a rule, not recommended since the plates of a car battery can simply be burnt.

how long to charge a car battery with a charger

You can find out the load your car battery experiences according to the amount of current that’s necessary for various devices of a car. For example, if there is low beam light turned on in the headlamps of your car, on average, from 8 to 10 amperes will be required. In case you turn on rear window heating, approximately the same amount will be required. In theory, a fully charged car battery, that is not provided with current from the alternator, should spin the starter for, approximately, 10 minutes, provide enough current for the function of the headlamps for 8 hours and enough current for heating rear window for 12 hours. However, as a car battery is discharging, this time is significantly decreasing as well.

A usual charging device for a car battery that you can use at home includes a transformer and a current rectifier that allow to convert 220 V of alternating current from a socket to 12 V of direct current. Besides, these devices make it possible for power source itself to define the best speed of charging in accordance with a car battery’s condition. In case a car battery is quite new yet, a charging device can increase the intensity of current for up to 3-6 A. Therefore, such like car battery will be charged faster. If a car battery is very old and you used it for a long time, such like battery simply won’t hold its charge at all. That’s why it simply won’t be charged even if a special charging device is used.

How To Charge A Car Battery With Charger? Step-By-Step Instruction

The first thing you need to do is take the car battery out of your car. You do it by detaching 2 wires of negative and positive charge from corresponding battery terminals. Make sure that all the devices of your car that use electricity for functioning are turned off. This mean that not a single lamp on the dashboard of your car should light up, the ignite key should be turned to the “Off” key and car audio system should be turned off. If some of the devices are left working, there will be sparking in the place of connection when you take the car battery out and, then, connect the charged car battery once again to the car’s power wires. Once you take the car battery out, strip the contacts of the car battery’s terminals and wires to establish a better connection later on.

how to charge car battery using charger

Plugging In A Charging Device

Before you start the process of charging your car battery, remember to always check the level of electrolyte. There is a special small window on the shell of your car battery that will help you do it. If necessary, pour some more electrolyte inside the car battery, clean and wipe the battery’s terminals. Set up the clamp of the positive (+) wire of the charging device on to the positive battery terminal. As a rule, the clamp of the positive wire is red and the positive battery terminal is bigger in size than the negative one. The same way you set up the clamp of the negative wire on to the negative battery terminal.

how to recharge a car battery with a charger

Plug the charging device in the socket and turn it on. The indicator or the sensor (the ammeter) will show you that the car battery is currently being charged. At first, the indicator may show you that the battery is charging fast. However, the speed of charging should, gradually, decrease during the course of charging. If your charging device doesn’t have the function of the automatic intensity of current change, you need to set it manually. The maximum value of intensity of current amounts to 10% from a battery’s capacity. The best value of intensity of current when charging should amount to 5%. In case the battery’s capacity is 60 Ah, the intensity of current you are to set in a charging device while charging is 3 A. If you increase it up to 6 A, you are likely to damage your car battery. Remember that the lower the intensity of current is, the more time will it take for a car battery to charge. However, the service life of a car battery in this case will be longer, considering the fact that you will have to charge the battery from time to time when it’s discharged.

Can I Charge My Car Battery In The Cold?

Yes, you can. While charging, a car battery is being heated. Therefore, the electrolyte’s temperature will, anyway, be above zero. You drive your car in winter, when the temperature is, as a rule, below zero, and the alternator successfully charges your car battery. It is forbidden to charge a car battery no matter what the temperature is in case it was severely discharged and, due to very cold weather, the electrolyte is frozen and turned into ice. It is necessary to bring such like car battery to a warm place and start charging it only after the ice melts.

How To Know That A Car Battery Is Fully Charged?

How To Know That A Car Battery Is Fully Charged

If during the process of charging you notice that the intensity of current has stopped to increase and the charging current has been one and the same for more than 1 hour, it means that your car battery is 100% charged. In case of modern maintenance free batteries, the current voltage should increase up to 16,2±0,1 V. However, this value depends on the current of charging, a car battery’s capacity, the density of electrolyte and other factors. The mentioned value is just for you to consider. In order to measure the value, you can use a voltmeter with any precision grade since it’s not necessary to precisely measure the voltage. What is important is the value of the voltage being direct.

How Does A Total Discharge Of A Car Battery Influence Its Service Life?

It has a negative influence on the service life of a car battery. In case of modern maintenance free batteries, a total discharge is especially dangerous. The manufacturers of such like car batteries warn that even if such like battery is totally discharged only once, it may result in the battery being out of order and impossible to use later on.

how long to fully charge a car battery

How Long Time Does It Take To Fully Charge A Car Battery?

Once electrolyte starts to boil, a car battery can be considered to be completely charged. 8-10 hours is considered to be an average time for the charging of a car battery. However, the time mentioned is relative. Actually, the necessary time for the charging of a car battery may differ a lot. It depends on the level of a car battery’s charge when you start charging it.

Useful tip:

  • In order to extend the service life of a car battery for as long as possible it’s better to charge it in moderate mode and gradually. The current provided by a charging device should be direct. A charging device also includes transformers that convert alternating current to a direct one. Besides, a special charging device guarantees stable voltage and protects a car battery in case of voltage surges thus guaranteeing that the process of charging will be as safe as possible.


  1. Could anyone tell me if there is a difference between charging a car battery at home and charging it in a garage? There is no heating system in my garage. At the same time, it’s quite warm at my home. Under what temperature conditions it’s better to charge a car battery? I charge it at home usually. Still, I doubt there is any sense in bringing my car battery home in order to do it. The battery is definitely not that light to carry.

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