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How Long To Charge A Car Battery [By Amps]

Would you like to know how long it takes to charge your car battery depending on the amperage? Well, we have researched this question and have the answers for you. It is vital to know how long it takes to charge your car's battery at different amps to avoid damaging your battery.

Charging a car battery will take different lengths of time depending on the size of the battery and how many amps are being used to charge it. Here is a list of times to charge a standard 50 amp-hour car battery with different amps:

  • 1 amp - 48 hours
  • 2 amps - 24 hours
  • 4 amps - 12 hours
  • 6 amps - 8 hours
  • 8 amps - 6 hours
  • 10 amps - 4.8 hours
  • 20 amps - 2.4 hours
  • 30 amps - 1.6 hours
  • 40 amps - 1.2 hours
  • 50 amps - 1 hour
  • 200 amps - Not recommended

In this article, we will learn how long it takes to charge a car battery at different amps. We will also learn the answers to other interesting related questions, such as how long does it take to charge a car battery while driving and how do I know when my car's battery is fully charged? Keep reading to learn more.

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Attaching alligator clips on the car battery, How Long To Charge A Car Battery [By Amps]

How Long To Charge A Car Battery [By Amps]

Several factors determine how long it will take to charge a car battery. One of the most important factors is how many amps you use to charge the battery. While more amps will charge a car battery faster, it also increases the risk of overheating and battery failure.

Charging the car battery

It would be best to use the lowest amps possible to charge your car battery, but since we don't always have the time to let your battery charge slowly, selecting the lowest amps that still work with your timeframe would be best.

Let's look at the most common amp levels for charging car batteries and discuss how long they take to charge your battery from completely dead to full.

1 Amp

1 amp is by far the safest ampere for charging a car battery. With such low levels of power, your battery is sure to keep from overheating. The low power flow will also take the longest to charge your car battery.

If you are charging a standard 50 amp-hours battery with 1 amp, it will take 48 hours for the battery to charge fully. The time it takes to charge a car battery with 1 amp is why most people opt for a higher ampere to charge their car's battery.

2 Amps

2 amps is still a very low power flow, making battery failure extremely unlikely. With 2 amps, you can charge a 50 amp-hours battery in 24 hours which is exactly half as long as it takes with one amp.

The reason twice as many amps require half as much time is because there is a direct correlation between the number of amps used to charge a battery and how long it takes for that battery to charge.

There is also a correlation between the number of amps used and the heat generated, which is why more amps aren't always better.

4 Amps

4 amps can charge a 50 amp-hours battery in 12 hours. With only 4 amps, you shouldn't notice too much heat, but it would be best to check that your battery isn't overheating occasionally.

6 Amps

6 amps can charge a standard car battery in 8 hours. 6 amps should also not create a heat problem, but it would still be best to check on the battery every 2 hours for overheating.

8 Amps

8 amps can charge a 50 amp-hours car battery in 6 hours. Even at 8 amps, you shouldn't notice too much heat, but it would still be a good idea to check your battery every 2 hours.

10 Amps

Alligator clips attached to the car battery for charging

10 amps can charge a car battery in just under 5 hours. Heat is unlikely to be an issue at 10 amps, but if there is a short in the battery, then it may be enough to cause your battery to fail.

If your battery fails, it could leak dangerous chemicals. If you notice anything leaking from your battery, disconnect the power to the charger and contact a mechanic. Do not handle a leaking battery unless you have the proper protective equipment and know what you are doing.

20 Amps

20 amps deliver enough power to the battery to charge it in 2.5 hours. It would be best to check your battery every hour for signs of overheating.

30 Amps

30 amps can charge a standard 50 amp-hours battery in an hour and a half. If you charge your car battery at 30 amps, don't leave it unattended for the first 5 minutes to check for signs of electrical shorts like smoke or fire. Once you are sure there isn't a short, you can check on your battery every 30 minutes until it is charged.

40 Amps

40 amps can charge a car battery in just over an hour. Stay with the battery for the first 5 minutes to check for shorts and then every 20 minutes until your battery is charged.

50 Amps

50 amps can charge a standard 50 amp-hours battery in one hour. Like the previous two amperes, stay with the battery for the first 5 minutes to check for signs of shorts that can lead to battery failure.

Once you know that the battery is charging correctly, check on it every 20 minutes for signs of overheating until it's charged.

200 Amps

It is not recommended to charge your car's battery with any amps above 50. If you try to charge your battery with an amperage above 50, you risk critical battery failure, which can cause your battery to spray acid and even burst into flames. Never charge a car battery with any amperage above 50.

How Long Does It Take To Charge A Non-Standard Car Battery?

If your car battery isn't the standard 50 amp-hours, you may be wondering how long it will take to charge. If your battery has 60 amp-hours, it holds 20% more power than a standard car battery and will take 20% longer to charge.

Since the length of time to charge your battery scales so well with larger and smaller batteries, you only need to calculate how much bigger or smaller your battery is to find how long it will take to charge compared to a standard car battery.

How Long Does It Take To Charge A Car Battery While Driving?

A car moving on the highway with a scenic view of the mountains

Sometimes you don't have time to let your battery charge completely before you need to use it. The good news is that your alternator charges your battery while you drive. Often you only need to charge your battery enough to start your vehicle, and then driving will charge it the rest of the way.

How long it takes to charge your battery while driving depends mainly on how fast you travel. It will take longer to charge your car's battery driving through the city than on the highway.

If you are driving on the highway with speeds of at least 6omph, it should only take 30 minutes to charge your battery fully. In the city, the charge time can vary between 1-3 hours depending on your average speed.

Can You Charge A Car Battery While Idling?

Since the faster you drive, the faster your battery charges, you may think that idling won't charge your car's battery, but this isn't true. When idling, your engine still turns the alternator and charges your battery faster than your vehicle can use power.

Charging your car's battery while idling is the least efficient way of using your alternator. In theory, you could eventually charge your car's battery while idling, but it would take many hours.

How Do I Know When My Car's Battery Is Fully Charged?

Technician testing the car fuse box

To tell when your car's battery is fully charged, check its voltage with a multimeter. When the engine is off, you should expect a fully charged car battery to measure 12.6 volts or higher. If you check the battery while the engine is on, the voltage of a fully charged battery should be closer to 14 volts.

If you need a multimeter, here are two of the highest-rated ones available on Amazon.

KAIWEETS Digital Multimeter

You can find this product here on Amazon.

IKOVWUK Multimeter

You can find this product here on Amazon.

If you don't have a multimeter and need to quickly check how charged your car's battery is, try the headlights test. Your car's headlights will shine proportionally to the charge stored in your car's battery, allowing you to gauge if your car's battery is charging.

Final Thoughts

Attaching alligator clips on the car battery

This article taught us how long it takes to charge a standard car battery at different amps. We also learned that once you start your car, you can charge the battery by simply driving.

Remember that charging your car's battery with an amperage higher than 50 risks catastrophic battery failure, which can be very dangerous.

We hope you enjoyed this article. If you want to learn more, check out some of these other posts:

How Long To Charge A Car Battery With 12 Volt Charger

How Long To Charge A Car Battery With Jumper Cables?