How Long Does It Take to Charge a Car Battery?

Oh no. Your car battery is dead. What are you going to do now?

Unless you’re super savvy on vehicle maintenance, a car battery running out of juice is something that can happen to any car owner. 

You probably have a car battery charger in the trunk and getting ready to set it up.

But now you’re wondering, just how long it will take to charge the dead battery.

The simplest answer is that it ultimately depends on the amperage of the battery charger that you are using.

The time taken to achieve a full charge can vary from a few fours to a full day. 

Does that mean that I should always go for chargers with higher amps? 

Not necessarily.

While you can charge a dead battery much faster with a high amp charger, a lower amp charger may be more ideal if you’re looking to maintain your car battery at a fully charged level.

Of course, there are other factors worth considering, especially if you’ve never don’t this before.

Let’s go through them:

What are the determining factors?

One of the first things you’ll want to consider before hooking up your dead car battery to the charger is why it got drained in the first place. 

There are numerous reasons your battery is unable to provide your car with enough electricity.

For one, the battery could be getting too old to function properly, in which case you need to start looking into the possibility of a replacement in the near future. 

There could also be some damaged parts in the battery, probably due to long-term exposure to corrosion and inclement weather.

Left unchecked, these factors can speed up the wear and tear of the battery and even the surrounding engine parts. 

The key thing to note is that if the battery is just drained but still in working condition, then charging it and keeping it charged may be the only thing you’ll need to do.

However, if charging the battery doesn’t work, then there might be irreparable damage within the system; in which case, you might have to get a new one.

The good news is that if you decide to replace your car battery, you can always sell the old one and make some extra cash on the side.

Remember, it can be dangerous to charge a damaged battery and that’s why it’s important to first check the determining factors before you begin. 

Consider the size of the battery 

The size and type of your car battery can also play a key role in how long it will take to be fully charged.

In many cases, larger batteries can charge faster than smaller batteries since they hold more energy and can take in a larger voltage or charge current. 

What’s the best amperage for charging my car battery?

Again, there is no one right answer. Usually, the right amperage for charging your car battery will typically depend on how fast you want it to go. 

If you absolutely have to be on the road in the next two to three hours, then charging the battery with 40 amps may be the best way to go.

At 40 amps, even a totally depleted, but good working car battery may be able to start after a couple of minutes charge.

Plus, it can provide an effective jump start using jumper cables. 

That being said, fast charging for long periods of time can cause damage to your battery and reduce its useful life expectancy.

So which should you go for instead?

Let’s take a look at the battery charging times at different amp levels so you can make an informed decision. 

Car battery charging time at 4 amps

A deep cycle battery normally holds 48 amps, so if you charge it at 4 amps, then it should take around 12 hours or so to get it fully charged.

While it is hardly the go-to choice when you want to achieve a quick charge, charging at 4 amps can protect the car battery against potential issues relating to overly high voltage. 

Car battery charging time at 2 amps

At 2 amps, it will take approximately 24 hours to fully charge a depleted 48-amp car battery.

As such, this type of charge is best utilized when the battery already has some juice and you simply want to maintain it at a probable charge. 

Additionally, you can use a 2-amp charge on car batteries that are seldom used since there isn’t much risk of connecting it to the charger for a long period.

For instance, if you have an antique vehicle in your garage that you only drive once in a blue moon, then charging its battery at 2 amps may be ideal. 

Car battery charging time with a trickle charge

This is a great option if you’re planning to leave your car unused for a very long time, maybe months. A trickle charge can prevent the battery from completely running out following lengthy periods of unuse.

It will take a much longer time to charge for sure if the battery is already depleted, but since you’re not planning on taking the car out any time soon anyway, there’s no rush.

Just remember to check on it every now and then to make sure everything is still going as expected. 

Choosing the Right Type of Car Battery Charger

Now that you have an idea of the possible car battery charging times based on the amperage, it’s time to look at the type of charger that you’re using. 

Ideally, you want to go for quality smart chargers with a charging monitor system to regulate the amps as needed.

So it can start off with a 40-amp charge and gradually lower amperage as the battery approaches a full charge.

Modern smart chargers can also automatically switch off when the battery is fully charged. 


While it is important to know how long it takes to charge a car battery, it is ultimately more crucial that you know how to avoid getting the battery depleted and being proactive with the overall car maintenance.

That means remembering to always turn Off your car’s electrical devices and keeping your car running every now then. 


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