Hi, I'm Luis Johnson, an automobile technician, and power equipment professional. By profession, I'm a businessman and operate a car workshop. I have created this...Read more
A car battery dying on you when you’re out on some important business can frustrate you. In such moments of need, the best method of reviving your car battery would be to jumpstart it with the help of another charged car battery.
You can partially charge a car battery with jumper cables by connecting the jumper cable to another charged battery. However, you can’t charge the battery fully. You will need 14.5 VDC for AGM batteries to charge it fully, whereas another fully charged battery only has 12.6-12.8 VDC.
This guide will show you step by step how to charge a car battery with jumper cables as much as possible.
How Can You Fully Charge a Car Battery with Jumper Cables- Step-By-Step Guide
Now that we have established that we can charge a car battery with the help of jumper cables let’s dive into this process’s dos and don’ts.
If the battery of a car is dead, using a jumper cable to connect the dead battery to another car’s battery is a good way to jumpstart it. In order to do that, you will have to make sure that you have connected the cables in the right and safe way.
The positive terminals of both car batteries should be connected together. For instance, the red clip of the cable will indicate the positive terminal. Besides, the negative terminals of the batteries should be attached to the jumper cables.
Here is the complete step-by-step guide to charging a car battery with jumper cables:
Check the Car Battery
The first thing you should do before charging your battery is to check the physical appearance of the car battery. Ensure that the battery is completely dry and safe; there is no acid leakage from the battery.
Additionally, the battery should not have cracks and damage to the external body. It makes the whole process of charging it with a jumper cable unsafe for everyone involved.
Take Safety Precautions
You should always take a few safety measures before touching any part of the car battery. Do not touch the battery with your bare hand at any point.
Wear a safety goggle to protect your eyes from fumes or acid. Wear safety rubber gloves to prevent being in contact with any electric discharges or sulfuric acid that might leak from the battery.
Position The Cars Properly
To use another car’s battery, you will have to keep both cars in a certain position to ensure a smooth charging process.
The position of the cars should be close to one another. They can face the same direction or be nose-to-nose in the opposite direction. Make sure that the cars do not touch each other at all.
The cars should be close enough for the jumper cable to be connected properly to both batteries. If the jumper cable is not long enough, you have to get new ones.
Don’t connect two different jumper cables to cover the distance between the two car batteries. It won’t help the charging process; instead, it can melt the cables. Situations like this can lead to an accident by creating a fire.
Connecting The Jumper Cables Properly
This is the most important part of the whole process. Connecting the jumper cables in the proper order is absolutely necessary.
Follow this pattern of connecting the jumper cables to the batteries:
- Identify the positive and the negative terminals of the batteries. The positive battery terminal will be marked with a plus (+) sign, and the negative battery terminal will be marked with a minus (-) sign.
- First, connect the red clamp of the jumper cable to the positive battery terminal of the good battery.
- Connect the jumper cable’s second red clamp to the dead battery’s positive battery terminal.
- Then connect the black clamp of the jumper cable to the negative battery terminal of the good battery.
- Lastly, connect the second black clamp of the jumper cable to a grounded metal component of the dead battery. It can be an exposed part under the hood that is free of paint and dirt.
Start The Engine
Firstly, start the car’s engine with a good battery to start charging.
Wait for about 5-10 minutes. It will give the dead battery some time to build up a charge of its own. Then try to start the car with the previously dead battery.
If it does not start at the first attempt, give it five more minutes and then try again. If the battery gets charged enough and gets revived, the car should turn over and start easily.
Disconnect The Jumper Cables
After you are done charging the battery, you need to disconnect the jumper cables in a proper manner as well. Disconnect the jumper cables in the reverse order you connected them at first.
Follow this order while disconnecting the jumper cable from the battery:
- First, disconnect the black clamp from the grounded part of the car.
- Then disconnect the black clamp from the negative terminal of the battery.
- Disconnect the cable’s red clamp from the dead battery’s positive side.
- Lastly, disconnect the red clamp of the cable from the positive side of the good battery
Why Does the Car Not Charge Fully with Jumper Cables?
Jumper cables are a really viable way of jumpstarting your car battery. However, it can not charge the battery fully. Your car battery will only be charged partially via the jumper cable connected to a good battery.
In order to fully charge a car battery, you need a higher level of voltage than another car’s battery can provide. For example, you will need 14.5 VDC for AGM batteries to charge the car battery fully. On the other hand, a car battery will only provide you with a voltage of 12.6-12.8 VDC.
Therefore, there is not enough voltage for the car battery to charge fully. Plus, when you connect two car batteries through a jumper cable they reach an equal position and then restrict the flow of electricity among both batteries. Suppose, your dead car battery has 20% of power and the new batteries have 80% of the power. Now if you connect both of these batteries through a jumper cable, then both of them will end up with 50% power which is half of both batteries’ total power.
However, you need to run the car for about 15 to 20 minutes after starting the engine through jumpstart. The alternator will charge the battery over this time. You can also use an external charger to complete charging the battery.
There are a few commonly asked questions about charging a car battery with jumper cables. We will try to answer a few of the most asked questions here.
How Long Does Charging a Dead Car Battery with Jumper Cables Take?
A weak or dead battery can take from 10 to 15 minutes to charge enough to get started with jumper cables. It mostly depends on how depleted the battery is. A completely dead battery can take even longer.
What Happens if You Leave Jumper Cables Connected to The Battery Too Long?
Leaving jumper cables connected to the battery for too long can overcharge the battery. The jumper cables will eventually heat up and short out, damaging them beyond repair.
How Long Should You Leave Jumper Cables On?
After the car with the weak battery is turned on, you can leave the jumper cables on for two minutes. Then wait another two minutes after turning the engine on. The jumper cables should be disconnected after this time.
In conclusion, you can temporally charge your car battery with jumper cables in case of emergency. But it will not charge the car battery fully. You will need to use an external charger in order to top up the charge fully after jumpstarting the car.
Keeping your car battery charged and healthy is mandatory use for a long time. Incorrectly charging the car battery might lead to risks and can be a danger to both the car battery and yourself. So, follow every step of this guide to charging your car battery when you need it safely.