How Long to Charge Car Battery: Specialist Tips


Many car owners know that feeling when their car battery dies, and it isn’t a good feeling. Imagine you’re just about to begin your workday and your car just won’t start? What a nightmare! Having to deal with an irritated boss is only going to be the cherry on top of an already ruined day. A drained car battery is what starts it.

Preparing ahead for this kind of situation is the best way to go. If you make sure you always have a car battery charger on hand, you’ll be able to get your vehicle running without any external help. But how long do you need to charge a car battery for? How long does it take to charge a car battery?

If you’re new to all this, you have nothing to worry about. You’ve come to the right place! Using our extensive auto knowledge, we’ll guide you through the process of recharging a dead car battery. Keep reading to find out how long to charge a car battery for & all the extra info you might need.

Why Do Car Batteries Fail?

The first question you might ask yourself is why this even happened. Why is your car’s battery dead? Rather than dwelling on the problem, this bit of knowledge may help you avoid the problem in the future. Below, we will list some of the most common reasons for car battery failure.

Charging failure

If you usually drive in the nearby vicinity and do not venture out far, you may find your dead car battery suffering from a charging failure. The battery normally gets charged while you are driving, but if you rarely go for long-distance drives, it simply doesn’t get the chance to. In that situation, the alternator is unable to keep up with the charging process and you may find your battery fully drained.

Using extra in-car features

Just driving takes up a whole lot of the battery, but if you tend to use the in-car features a lot, the battery will drain much faster. An example of this is if you use the AC a lot, charge your devices via a car charger, or tend to use the built-in radio. All of these tend to add up quite quickly and drain your battery.

The battery is getting old

This is one of the most common reasons why your battery may die or may require frequent recharging. Car batteries, like most car parts, have a certain lifespan and if your car battery is approaching that mark, it will become more and more unreliable.

Damage to the battery and/or the car

If the battery is acting up and dying on you without any obvious reason, there may be some damage to the battery itself, or worse yet, to the engine. Things such as corrosion or cold weather contribute to wear-and-tear and may cause serious failures.

Charger Types

No matter the reason, as long as your car is still fit enough to be charged, you have no choice but to charge the battery. If you have a car battery charger on hand, you’re all set. However, if you find yourself without one, it’s good to know which type might work best for you.

Linear chargers


A linear charger is the simplest tool that helps you charge a car battery. Linear chargers plug into a wall socket and provide hassle-free recharging. While they are very simple to use and don’t require any prior knowledge, they are not the fastest. Can’t have it all, right?

These chargers start at around 2.7 amperes. Such a car battery charger would take up to 12 hours to charge a 12-volt lead-acid battery, which is what you will find in most vehicles.

A linear battery runs at a continuous, steady charge, and cannot be controlled in order to stop when the battery is full. This means that you need to always keep an eye on your linear charger and turn it off at the correct time. Otherwise, you risk damaging the battery, ranging from simple failures at best to an explosion at the worst.

Multi-stage chargers


A multi-stage charger is more expensive than a linear charger, but it does come with its own set of perks. Multi-stage chargers differ from linear chargers in how they recharge the car battery. They recharge in bursts instead of providing a steady stream of power. This is the preferred method where battery cells are concerned, as it makes sure that you don’t damage the battery, which may otherwise when you use a linear battery.

These chargers also have a much higher ampere value than linear chargers. You can purchase a multi-stage charger that will have up to 50 amperes. This means that a standard car will be charged in less than an hour.

Trickle charger

Trickle chargers are objectively the weakest of all and cannot be used to revive a dead car battery. They operate at 0.8 amperages and 4 amperages. This low output level means that trickle chargers have limited use, but there is one thing that makes them stand out in a good way. They can be used to prevent car battery problems if they are connected to the battery when your car isn’t running.

One of the best choices when it comes to a trickle charger is the Enhanced Flooded Battery (EFB). These charge relatively fast and operate at a low voltage, which means they can be used when your vehicle isn’t running. They are also good to use when the battery isn’t fully drained just yet.

Which Car Battery Charger Is Best?

If you want to get the best car battery charger out there, avoid the cheap, off-brand products that you may find in stores or on the internet. You want to aim higher and get yourself something good, as the charger has a huge effect on how well your car performs, and whether it runs at all!

It’s worth noting that off-brand, cheap knockoffs often lack monitoring features. This means that they may put out fewer amps than advertised, resulting in extremely slow recharge times.

Not sure what to buy? Aim for something high-quality and at least in the medium price bracket. As far as amperes go, a 4-8 ampere range is the minimum for a mid-sized car battery. It’s also good to have a jump starter in your car at all times.

On the other hand, if you don’t need a charger that will quickly fill up the battery but you want to maintain your car battery at a certain level, a high amp charger won’t do. You should use a low amp charger if you want to simply maintain the battery at full charge at all times.

How Long Does It Take to Charge a Car Battery?

This is a question many car owners tend to ask. If you’re in a hurry, you may be counting minutes until you can finally get back on the road.

However, charging a car battery is not a very quick business, and the length of the charge time to recharge the battery depends on many factors. If you want to start your car and you neglected your trickle charge, you may wait for quite some time until you are able to start it again.

The higher the amps, the quicker the charge time — treat that as the rule of thumb. It may take hours to charge your battery. However, if you’d like to hear some specifics on how long it takes to charge a battery, we’ve got those prepared for you.

How Long Does a Car Have to Run to Charge a Dead Battery?

If the worst has happened and your car won’t start, the battery might be fully depleted. The good news? You don’t have to charge it up to full right away. If you’re in a hurry, you can get back on the road before the battery is charged to full. Obviously, that will take less time than the full recharge (which you still need to do as soon as possible).

Let’s talk about some of the variants on how long it might take your car to start.

The car starts up normally

If the car is able to start normally, it will only take a couple of minutes to recharge the battery back to the point it was at before you started it. Of course, the amperage plays a factor in this, but generally, you should be able to keep running your car as normal even if the battery is near-depleted — as long as you are charging it.

The car takes some time to start

Now, if the car is slow to start or it’s very cold outside (we’re talking freezing temperatures), the battery will need more time to get your car up and running. In those situations, you may expect your car to need at least 30 minutes to recharge & start properly.

The car is not starting

Before we can determine the fix & how long it’ll take to restart your car, it’s important to check just how dead the battery is. The way to do this is to use a voltmeter.

A healthy, non-malfunctioning battery should show around 12.4-12.7 volts across both terminals. However, if the voltmeter reads lower than 12.4 volts, you may be unable to start your car. Depending on how much lower the volts go will determine whether you can simply recharge the battery or you will need to use jumper cables.

Car battery above 12 volts

If the battery reads between 12 and 12.4 volts, you can use the car’s alternator to recharge it. This means that you will have to drive around without using all the extra in-car features, such as AC, stereo, lights, heating, and more. Do not do this at night, as you need to keep your car lights off.

You will need around a 30-minute drive in order to get the battery back to the right level. However, if your car battery reads below 12 volts, your vehicle’s alternator will not suffice in order to start the car.

Can a completely dead battery be recharged?

Anything that reads below 12 volts can be referred to as “completely dead”. This means that the battery is considered to be discharged. At this point, you cannot use the alternator to save the battery, as it was never designed to completely recharge & revive a dead car battery.

We need to stress that you shouldn’t even attempt to use the alternator in order to recharge a dead battery, as you may actually end up damaging both in the process. The alternator takes a hit when it tries to fill up the battery while still keeping the vehicle alive; the battery also gets hurt and may not even hold the charge.

If the battery is this depleted, your best bet is to connect a jump starter to it. Alternatively, connect a dedicated battery charger either right before or immediately after a jump-start.

Both of these devices are safe to use and will restore a dead battery to full charge. Most commonly, you won’t even have to remove the depleted battery from your vehicle when you use a jump-start kit

How long does it take to charge a car battery with a 12-volt charger?

The amount of time required to charge a car battery with a 12-volt charger depends largely on the number of amps you use. Below, we will discuss the most common scenarios.

Using 40 amps

If you use forty amps to charge the battery, the car will be charged very quickly. This is good if you need to get back to driving fast, as it may take just a few minutes to fully charge the battery. However, be careful not to overcharge the battery, as that is almost certain to damage your battery.

Using 12 amps

Before you use a 12-amp charger, make sure that you don’t use it by charging from a circuit with multiple outlets and devices. Keep in mind that you also have to figure out the circuit breaker & wiring that your outlet has before you choose to use a 12-amp charger. Ideally, you will get 5 miles of range per hour of charge when using 12 amps.

Using 10 amps

Assuming your car battery is small and about half-discharged, you will be able to restore it to full in about 2-3 hours using a 10-amp charger. If you’re lucky, it won’t take much time to charge — one hour of battery charging may sometimes suffice. If the battery is medium-sized, the amount of time required will go up to 3-4 hours. For a large-sized battery, you can expect anywhere between 4 to 7 hours.

Using 4 amps

If you use 4 amps, you have to expect it to take a bit of time for a full recharge. You will need about 12 hours to reach a full charge if you use this voltage. This is because car batteries generally hold 48 amps. 4 amps is a good choice if you simply want to maintain a certain level of battery charge for a prolonged period of time.

Using 2 amps

Using a 2-amp battery will take you about 1-2 days until your car battery is back to full. This comes down to the fact that the 2-amp battery provides just 1 ampere per hour. You will most commonly use these batteries when doing a trickle charge or to maintain the battery level at a specific number.

How do you know when a car battery is fully charged?

The best way to tell if your car battery is fully charged is to use a voltmeter, also known as a multimeter. These simple devices tell you all you need to know about the battery & guide you as to when to stop charging.

A fully charged automotive battery should measure at 12.6 volts or above. If your engine is running, the measurement goes up. For a running engine, expect 13.7 to 14.7 volts for a fully charged battery.


Keeping your vehicle battery in top shape is extremely important. As long as you are diligent with your recharges and you keep an eye on battery levels, you should rarely find yourself in a situation when the car cannot start. However, if that happens, there are still things you can do to get back out there.

Remember to frequently charge your battery with a low-amp charger and don’t stress out if you sometimes run into trouble. With just a bit of time, you’ll be on the road soon enough!

About the Author: Ben Flynn

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