How to Charge a Car Battery? A Quick and Easy Guide
Suppose you have to go to attend an important business meeting and when you start your car in the morning, you get to know its battery is running out of power. This becomes a frustrating situation. Isn't it?
The question that arises here is “What to do when the car battery can't start the engine?”. You can ask a neighbor to help you jump-start your vehicle with jumper cables. Alternatively, you can use a portable jump starter to jump your car. But it's not enough.
The next thing you should do after jump-starting your vehicle is to recharge your car battery, especially if you plan not to drive regularly. This is where a battery charger lends you a helping hand. Whether you are searching for how to charge a car battery or are looking forward to buying the right charger for your dead car battery, the discussion below has got you covered.
How to Charge Your Car Battery? A Step-By-Step Guide!
If you're wondering how to charge a battery for your vehicle, this section will guide you through the steps you should follow while charging your car. Let's get into detailed specifics.
Step 1: Locate the Battery
The car battery is usually placed under the hood by the manufacturer. Once you find the battery, identify its positive and negative terminals. The positive terminal is mostly marked with the “+” symbol, whereas the negative terminal is marked with the “-” symbol.
Sometimes, plastic covers are used to protect battery terminals. If your car battery is protected with plastic covers, you can simply flip them out to make the terminals ready for the connection.
Batteries may also be there in the trunk of some cars. If this is the case with your car, you'll find the battery's positive terminal and have to use the under-hood sheet metal as a negative terminal. If you still can't find the battery or identify its terminals, consult the manufacturer's manual.
Step 2: Ensure the Charger Is Off
Before connecting the charger to your car's battery, don't forget to ensure that no current passes through the charger. The reason behind this fact is that if the current flows through the charger and you try to connect it to the battery, it can be extremely dangerous to leaky batteries.
When you unplug the battery charger before establishing the connections, it ensures there are no sparks. Remember, each charger works differently; therefore, ensure to read the instructions before using.
Step 3: Connect the Charger to the Battery Terminals
Now that you have found the battery, identified its positive and negative terminals, and made sure that the charger is unplugged. It is time to connect the battery charger to the battery terminals.
As you know, the charger has two clamps: red and black. First, connect the red clamp to the positive battery terminal, and then attach the black clamp to the negative terminal of your car battery. Don't forget to check if the clamps are tightened perfectly.
Considering the length of cables, keep the charger away from your car battery as much as you can. Doing this ensures greater safety.
Step 4: Turn On the Charger & Set Amperage
It is time to start the charging process. Some smart chargers can automatically identify if the batteries are connected to them. While others may need this information to be entered manually. Once the charger detects the connected battery, all you need to do is set the right charging amperage according to your requirements.
In case you don't know why the amperage setting matters, low amperage means slow charging while a higher amperage setting leads to faster battery charging. It is a general rule of thumb. It's advisable to charge your vehicle's battery with low amperage settings, as it extends the battery life and is more gentle on it.
Are you wondering how long a 12V battery charger will take to charge your car battery? Well, it all depends on the charger's amperage. However, the charging time varies between 10 and 24 hours. A 12V 2-amp charge may take around 25 hours to charge the battery fully, whereas a 12V 20-amp charger can complete the charging process within 2.5 hours only.
Important Note: Some chargers come with auto shut-off features, which means they are turned off once the battery is fully charged. In contrast, other charger types may have gauges to display the charging status of the battery. A typical charger delivers 2-6 amps. At this charging rate, a dead car battery can take several hours to recharge fully. Double-checking the instructions that come with the charger make sure you are using it correctly.
Step 5: Disconnect the Charger
As soon as your car battery is charged, turn it off and unplug it. Once done, remove the charger's clamps from the battery terminals. This time, remove the black (negative) clamp first, and then move toward the red (positive) clamp. If the terminals were protected with plastic covers earlier, close these covers again. Start your car to make sure the battery is functioning properly.
How to Choose the Right Battery Charger for Your Dead Battery?
The current market offers a range of car battery chargers, including trickle chargers, battery maintainers, and smart chargers. Since they are different devices, it's important to know their operations before picking one of them. Let's explore each charger before picking the right one.
1. Trickle Charger
This charger is known for charging the car battery at a slower rate. It delivers 1-2 amps of current to charge the battery. It may take a couple of days for the battery to charge fully. It stops automatically once the battery is charged.
If you don't often drive, this charger type should be your ideal choice. A trickle charger usually plugs into a wall. However, solar-powered trickle chargers are also available in the market these days.
2. Smart Charger
As the name suggests, they are designed with advanced techniques to charge your car batteries like never before. While charging the battery, a smart charger precisely measures the current and voltage levels. Some smart chargers can also determine the type of battery (AGM, flooded, lithium-ion, or more) attached to them.
The charging time depends on the amperage settings and how discharged your battery is. You can keep these chargers in the garage to charge batteries once you find that they are weak. It happens rarely, though.
3. Battery Maintainer
A battery maintainer is also known as a battery tender. It doesn't exactly charge your vehicle battery, instead, it detects the voltage level and delivers more power to the battery to maintain the same voltage. For example, if you connect a battery maintainer to your car battery that is 80% charged in the fall, it will maintain its voltage level (80%) in the next spring. This is how a battery maintainer works.
Simply put, a battery maintainer is turned on when the battery's voltage drops and turns off when it reaches the same voltage again. The battery tender or battery maintainer is a great option to protect deep-cycle batteries that are usually used in boats and other marine applications. Do you know that most smart battery chargers (when they charge the battery fully) work in the same manner as the battery maintainers do?
Note: Different chargers perform differently in different situations. Considering the features of all charger types, you can choose the one that perfectly fulfills your charging needs.
When Should I Recharge a Car Battery with a Battery Charger?
As you know, the vehicle's alternator keeps your battery charged. The question that may come to your mind is, “When should you charge the car battery externally using a charger?”. If this thing pops up in your mind, below are the situations when you need to use an external charger to charge your car battery.
- You left the lights on overnight accidentally.
- You have recently jump-started your vehicle.
- An unusual accessory behavior
- Sluggish or slow start
- You notice changes in the ignition sound.
How Long Does It Take To Charge a Car Battery?
The charging times may vary depending on two potential factors: the battery's status and the charger's amperage. If the battery is too weak, it may take more time to recharge. At the same time, a charger with a higher amperage will charge your battery faster.
The standard chargers take 4 to 8 hours to fully charge your car battery (if it is not completely dead). The chargers are usually designed to deliver low amperage and high voltage to prevent the generation of excessive heat. Car battery chargers can reach 13-14 volts at max.
If you use a digital multimeter to check the battery's voltage while the car is running, you'll find 14 volts for healthy batteries, as the alternator tries to charge the battery in parallel.
In contrast, battery maintainers or trickle chargers may take several days to fully charge your car battery.
How Can I Recharge a Totally Dead Car Battery?
No, you can't recharge a battery to 100% that is totally dead. If your car battery has reached 0% charge, it's already in the state of permanent damage. The potential question here should be “Can you prevent a dead battery from further damage?”. The correct charger may activate some dead components.
The reason why you can't fully charge a dead battery is the formation and hardening of sulfate crystals on the battery's lead plates. This process is called sulfation. It reduces the battery's ability to hold a charge.
Remember, if you leave the battery discharged for an extended period, the damage becomes permanent. However, a quick recharge may protect some of your battery's capacity. But, a sulfated battery will not perform as a new one does.
Charging a Car Battery FAQs
What is the proper way to charge a car battery?
First, ensure all electronic components are off. Then, connect the charger correctly to your battery terminals, and turn it on.
How do you charge a car battery at home?
Connect the unplugged charger to your battery and turn it on once connected. Ensure to remove the clamps once the battery is fully charged.
Does driving a car charge the battery?
Yes, the alternator charges the battery when the car is running.
Final Thoughts
If you're stuck somewhere due to a weak car battery, you can use a portable jump starter or ask a friend to jump-start your vehicle with the jumper cables. These methods will only start your engine and not charge the batteries.
So, how to charge a car battery? You can use different battery chargers to charge the car battery, such as battery maintainers, smart chargers, and trickle chargers.
The answer to the question “how long to charge a car battery” is 4-8 hours, depending on the charger's amperage rating and the battery's discharged status.
