How Long Does It Take to Charge a Car Battery? (Various Scenarios Explored)

A dead car battery can be inconvenient and put you in a difficult situation, and an undercharged battery can cause all sorts of problems with other car components.

Overcharging the battery can lead to overheating the battery, causing the distilled water and sulfuric acid inside its power cells to boil. If the battery overheats, the power cells can fail, making the battery unchargeable.  In extreme cases, this can melt the battery.

Knowing the time it takes to change your car battery can help you keep your battery in good shape and help you maintain a schedule if your battery needs frequent charging.

Most battery chargers cut themselves off once the battery is full, but it is good to know how long it will roughly take to charge to avoid any problems that could damage your battery.

How Do You Know a Battery Is Fully Charged?

You need a voltmeter or multimeter to determine if your battery is full. Hook the voltmeter up to the battery while the car is off. It is pretty well charged if the reading is at 12.4 to 12.8 volts. While the vehicle is running, you should get a reading between 13.7 and 14.7 volts.

If you don’t have a voltmeter, you can check by starting the car and turning on the headlights. They should be at their normal brightness. Rev the engine and see if there is a change in the brightness of the headlights. If there is no change, then your system is working correctly, and your battery is entirely changed and working optimally,

How Long It Takes to Charge a Battery in Different Scenarios

There is no set time to know how long it will take to charge a battery. It depends on the equipment you are using and the type of battery you are charging. Below are estimated times based on times for standard 12-volt batteries,

How Long Does It Take to Charge a Completely Dead Battery?

Up to 48 hours. Most standard battery chargers charge the battery depending on the amperes the charger produces and how you are charging the battery. Using the car’s alternator to charge the battery will take a lot less time than an external battery charger.

How Long to Charge a Car Battery While Idling?

2 to 3 hours. The alternator will charge the battery while the car is idling. Still, it takes a long time because the serpentine belt that connects the driveshaft and alternator slowly spins when idling, producing less electricity than if the car was moving.

How Long to Charge Car Battery After Jumpstarting?

At least 30 minutes. It is a common misconception that once you jumpstart the car, you only need to drive it around a block or two, and your car will be fine. This belief is inaccurate because it takes the alternator some time to generate enough electricity to charge the battery fully. If you turn the car off too soon after jumpstarting it, you may need to jumpstart it again the next time you go to start the vehicle.

How Long to Fully Charge a Battery When Driving?

Thirty minutes to an hour. The higher the RPMs, the faster the battery charges. If you are driving on a highway at a higher speed, the battery will charge more quickly. If you are driving around a city with a lower rate of speed with frequent stops and low RPM, then it can take a bit longer to charge fully.

You don’t need a fully charged battery to start a car, so you may be able to break up your drive time if you live in a city to charge the battery depending on what is causing the power depletion.

Using a Charger, How Long Does It Take to Charge a Car Battery?

A fully charged battery has 48 amperes of power. It is better for the battery if you change it slowly. Changing a battery too quickly can actually damage it and lower its life expectancy,

It is also essential to use a charger that cuts off when the battery is full. Overcharging the battery can cause it to heat up. Overheating a battery can cause the distilled water and sulfuric acid inside its power cells to boil. The power cells will die entirely if this happens, making it impossible to recharge the battery. In extreme cases, this can melt the battery.

Most chargers will charge a battery at one amp per hour.

2 amp24 hours
4 amp12 hours
6 amp8 hours
8 amp6 hours
10 amp4.5 hours
15 amp3.6 hours
20 amp2.2 hours
30 amp2 hours
40 amp1.3 hours
50 amp~1.3 hours

How Long Does It Take a 100 Watt Solar Panel to Charge a Car Battery?

It takes about fourteen hours of direct sunlight to charge a 12 V car battery. Depending on the time of year and the region you live in, charging the battery with the solar panel may take longer in chronological time than 14 hours. Most places don’t get 14 hours of sunlight in one day.

Plus, you have to consider places where the weather may not work along during part of a long summer day. It will likely take at least two days to get a full fourteen hours of sunlight.

How Long Does It Take to Charge a Car Battery with a Trickle Charger?

This type of charger generally only uses one of two amps of power to charge a car battery. Trickle chargers primarily exist to keep a battery charged so it can stay attached to the car as long as you need it to.

Some experts warn that a trickle charger can overcharge the battery because there is no mechanism to tell it to cut off when the battery is charged as a standard battery charge would have.

How Long Does It Take to Charge a Car Battery with a Generator?

If you need to charge a car battery with a generator, things can get a little tricky. You can hook your battery directly to the DC power outlet on the generator. The highest power output you can get would be about the same as an 8 amp charger, so it would take about 6 hours to charge at best.

DC power is as regular as AC power, so the voltage can change depending on the generator RPMs. It also varies depending on how many things the generator is powering at once. There is a good chance if you are using a generator, you need to power more than your car battery.

Another problem is that, like a trickle charger, a generator won’t know when to stop changing and can overcharge the battery.

The best thing to do would be to plug a car battery charger into the AC adaptor on the generator. The time needed to charge the battery would depend on the amperage of the charger you are using,

How Long Does It Take to Charge a Smart Car Battery?

The amount of time you need to charge a smart car battery depends on the type of smart car, the wattage of the battery, and the power output of the charging point.

For example, if the smart car had a sixty-watt battery, it would take 8 hours using a 7kw charging point to get the battery charged to full capacity.

The wattage of the battery depends on the make and model of the car.

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Author: Dave Johnston

Dave is a hands-on automotive technician with experience in performing service, diagnostics, and repairs on domestic and imported vehicles. He enjoys writing and sharing his knowledge far and wide.

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