How Long Does It Take To Charge a Car Battery?

Nothing frustrates divers in the morning when in a hurry other than handling a low-charged battery.

If you have been dealing with car battery issues lately, you probably must have been charging it often if you’ve no other alternative.

So, apart from tossing it out or calling your auto repair mechanic, how long does it take to charge a car battery?

Charging a car battery isn’t as easy as it may seem, as there are several tricks to ensure it is fully charged. Typically, it takes two to four hours for a full charge, but that depends on your charger output capacity or whether the battery is completely dead.

It could be your battery is at the end of its lifespan and can’t hold current or something’s wrong with your charging system.

Before interfering with external battery chargers, it’s essential to consider why your battery discharges unnaturally. Is it due to its age, a parasite load, a faulty alternator, or an overload on your car’s electrical system by multimedia devices?

In this article, let’s explore how long it takes to charge a car battery when you’re using every day charging implements.

What Causes Car Batteries To Lose Charge or Fail To Start Your Vehicle?

Car batteries are made up of lead metal panels immersed in sulfuric acid, used mainly for starting or cranking your engine alongside powering your car’s electrics. Although newer brands are SLA Gel-Cell, many of these battery types are wet or flooded, and Absorbent Glass Mat or AGM.

Other car battery types contain lithium-ion, but these aren’t used as starter batteries but for deep cycle purposes in electric-only and hybrid vehicles.

While lighter than their lead-acid counterparts, they’re longer-lasting, self-charging, but higher priced. However, you need a specified charger for this battery, which isn’t compatible with most AGM-style chargers.

If your car has an internal combustion engine, it should automatically charge the battery while running and keep it fully charged. However, your battery’s discharge may be attributed to several reasons, including:

  • The battery is old, or its lead panels have accumulated calcified deposits
  • Your car wasn’t in use for an extended period, and you never turned the engine on to idle charge
  • Parasite loads, such as your car’s security system drained your battery while on standby
  • You’ve used multimedia and other electrical systems such as air conditioning or lights while the engine is turned off
  • Your car’s alternator or a component of your onboard electrical system has failed
  • Extreme temperatures, such as cold or hot weather, are preventing your battery from recharging correctly

If one of these is the reason for your dead car battery, the best course of action is to recharge it using a dedicated smart charger.

For safety reasons, some vehicles don’t support the removal of batteries except in the presence of an authorized mechanic. As such, it’s best to consult your car’s owner’s guide to avoid additional issues that’ll only cost more to fix.

How Long Does It Take To Charge Your Car Battery Using an External Charger?

Factors like a battery’s age and size, capacity of a charging system, affect how long your car battery takes to recharge, plus whether or not it was fully discharged. If it’s empty of electric current, it can take anywhere between 12 and 24 hours to charge fully.

The simplest time to recharge is when there’s no battery malfunction or your car’s electrical charging system since you don’t need any extra equipment. However, this method relies on the battery’s ability to crank the engine so that you can idle the engine while the alternator does the rest.

Another method involves using a charger, which you can purchase online or at brick and mortar car maintenance shops. These devices deliver a direct electrical current to your battery with power from an AC outlet in a steady, slow stream.

Some chargers, especially those featuring desulphation or similar methods, shouldn’t be used when your battery is connected to the car. They use high voltage spikes to break down lead deposits, which can damage your car’s electronic system.

What Type of Chargers Should You Use To Recharge Your Car Battery?

Before recharging your battery, using a voltmeter allows you to determine how much charge is left while measuring the battery’s internal resistance for compensation. Typical lead-acid batteries at full charge will have a reading of 12.66 volts and 11.89 volts when empty.

The charger’s output determines the speed of charging your car battery to the full 12 volts, ranging from two amperes to 40. External charger types include linear, multi-stage, and trickle chargers.

Linear Chargers

It’s a simple car battery charger that you plug into a wall socket and is the fastest of these three.

Linear charging can take up to 12 hours from empty to full for a 12-volt lead-acid car battery.

However, these chargers don’t have controllers and will continuously charge if not carefully monitored, leading to overheating, shorter battery life, or explosion.

Multi-Stage Chargers

Compared to linear chargers, a multi-state charger carries a hefty price tag, and it uses bursts to charge your car battery. Its staged charging method allows higher amperes to support fast charging, and you’ll be fully charged in less than an hour.

Trickle Chargers

Charging your car battery with a trickle charge is safe since there’s no risk of overheating, as they operate between 0.8 and 4 amperes.

Batteries take between five and 12 hours to recharge fully, and you can do this while it’s connected to your vehicle. However, a completely dead battery may take upwards of two days or not charge due to the low power output.


So, how long does it take to charge a car battery?

The answer is anywhere between 12 and 24 hours. The safest and most recommended way to charge your car battery is by idling or while driving. When the engine is running, a belt-driven alternator sends power into batteries until they’re full, maintaining the charge.

While there are no risks of overcharging, heating, or damage, driving or idling your car’s engine remains one of the quickest ways to recharge your battery. It takes less than half an hour to reach a usable charge, and you can achieve a full charge in an hour. If your engine’s revolutions per minute or RPMs are high, the faster the charging and maintenance of power.

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Robert Muñoz

I’m Robert, a US-based auto electrician, auto mechanic, trained engineer and fanatic about all things motor vehicle. After studying engineering in college I returned to my original passion - car mechanics - and I ran a garage for a number of years serving my local community. Through my garage, I got involved in numerous road safety campaigns in my local area until eventually, I decided to share what I've learned with the world. Know more about me... You can follow me on LinkedIn.

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