How Long to Charge a Car Battery

How Long Does It Take to Charge a Car Battery

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If you own a car, waking up in the morning only to find the battery dead is something you’ve probably experienced at one point. If this happened unexpectedly when getting ready for work, the first step you probably took was to pick your battery charger from the garage to try and recharge your dead battery. While waiting for the battery to recharge, one question you must have asked yourself is how long to charge a car battery.

You see, recharging your battery is not always an easy fix especially when you’re in a rush. Many factors come into play, which can determine the length of time you’ll take when charging. Factors such as the battery’s condition and the amperage of the charger used can really influence the outcome.

So, in this guide, we’re going to discuss how long it takes to charge a car battery. Here, we’ll discuss the different types of battery chargers that are available and how long it takes to charge a dead battery.


But First, Why Do Batteries Fail?


Your car’s battery is an important component that powers the available electronics while still providing power to the engine during ignition. Although it might fail for the first time, charging your battery every morning is definitely something of a concern.

So, before we get to our main topic, it’s good if we can discuss some of the common reasons that can cause your car battery to fail.

  • Incompatible Battery:

Most modern cars are equipped with special batteries that are more efficient than their predecessors. These batteries are connected to the car’s onboard computer and the car’s fuel-saving systems to work more efficiently. One drawback with these batteries is that they fail or wear out prematurely if they’re replaced with the wrong type.

  • Severe Temperature:

Now, batteries are happiest when used in temperatures of around 30° If it gets extremely cold, the engine demands more cranking power to start. At the same time, the battery’s cranking ability lowers making it difficult to handle the engine’s cranking demands.

When it’s hot, the under-bonnet temperatures get too high causing evaporation and extreme corrosion inside the battery. This makes it difficult for the battery to maintain charge.

  • Worn Our and Dirty Terminals:

If your battery has worn-out terminals or maybe the terminals are dirty and loose, this can cause resistance that restricts full power from flowing from the battery to the starter motor. Also, this can prevent the alternator from charging the battery when the engine is on.

  • Failed Charging System:

The alternator is responsible for charging the battery. If the alternator has loose belts or a faulty diode, then this can prevent it from charging the battery sufficiently. The starter motor can also be a possible culprit. If the circuit is faulty, it can draw excess current from the battery leaving it entirely depleted.


So, Which are the Different Types of Battery Chargers?


Now that you’re aware of the common causes of car battery failure, we’ll now focus on our topic of the day which is determining how long it takes to charge a car battery.

Now, charging your battery can take anywhere from an hour to an entire day depending on the type of battery and the mode of charging you employ. Chargers with high amperage will most likely take shorter times to charge a battery than those with lower amperage. To explain this further, let’s look at the different types of battery chargers that are available.

Linear Chargers

Linear chargers are the simplest and the cheapest types of chargers that are used to charge a lead-acid battery. These chargers are mostly connected to a wall socket and are known to provide a very low amperage of just 2.7 amps.

The worst thing about these chargers is that they take a very long time to charge a battery, which mostly takes up to 12 hours. These chargers also run at a continuous charge and most of them lack a controller to monitor the charging process.

This is quite dangerous as you can risk overcharging your battery. The worst thing about overcharging a battery is that it can fail or explode depending on the situation.

Multi-Stage Chargers

Multi-stage chargers are the direct opposite of linear chargers. While linear chargers use a continuous stream of current to charge a battery, multi-stage chargers work in bursts. This charging strategy is friendly to your battery cells as it prevents long-term damage as well as common explosion cases that are very common with linear chargers.

Also, multi-stage chargers are costlier than linear chargers and have a higher amperage that ranges at 50 Amps. These chargers are quicker and mostly take up to an hour to charge a battery.

Trickle Chargers

The last type of battery chargers you’re likely to see are the trickle chargers. Now, unlike the previous two chargers, trickle chargers work in a very different fashion. These chargers are not meant to charge a dead battery.

Instead, they’re useful in preventing your battery from failing when your car is left untouched for a long time. For instance, if you park your car in the garage throughout winter, a trickle charger can be connected to your battery to keep it alive.

Trickle chargers run on very low power output and deliver very low amperage that ranges from 0.8 to 4 Amps.


How Long Will it Take You to Charge a Battery Using a 12V Charger?


The amount of time a 12V charger takes to charge a battery highly depends on the amount of amperage it packs. In most cases, the higher the amperage the lesser the time it will take for the charger to fully charge your battery.

Here are different charger amperages and the length of time they take to charge a lead-acid battery.

40 Amps Charger

These types of chargers are considered the best for charging car batteries. They’re quick and powerful and mostly take a few minutes to revive a dead battery. These chargers are convenient when carried along as they can help to jumpstart your battery in case it fails unexpectedly.

But, despite being so convenient, these chargers have one major flaw. They can damage your battery if left to charge for too long. Since they’re fast chargers, leaving them for too long can risk overcharging your battery which is not good at all.

For that reason, you need to buy a smart charger that can automatically switch from 40 Amps down to a trickle when your battery gets fully charged. This will help to maintain your battery rather than destroy it.

10 Amps Charger

A 10 Amps charger is considered less powerful than a 40 Amps charger. In most cases, such chargers can charge a dead small car battery (RC 40-60) in 4 to 6 hours and half the time if the battery is halfway discharged.

In the case of a medium-sized battery (RC 60-85), they can take around 6 to 8 hours and for large-sized batteries (RC 85-190), they can take approximately 8 to 14 hours.

4 Amps Charger

A 4 Amp charger is a smart option if you’re looking to charge a small RC 40-60 car battery. Since a fully charged deep cycle battery holds around 48 Amps, this type of charger will only take 12 hours to charge your car’s battery fully.

To those that use their cars for shorter drives, a 4 Amps charger can act as a trickle charger but only when it’s a smart charger. Here, the charger will automatically switch off when the battery is sufficiently charged and only switch on when the battery discharges.

2 Amps Charger

Using a 2 Amps charger to sufficiently charge a battery will take you a long time which can probably range from 24 to 48 hours. Due to their slow charging process, these types of chargers are mostly used as trickle chargers for maintaining car batteries but not for boosting them.

In fact, 2 Amp chargers are the best candidates if you’re planning to keep a spare battery connected for a long time until it’s needed. Combining this advantage with smart charging technology means that your charger will turn off and on automatically to maintain the battery charge.


What if You’re Using a Trickle Charger?


A trickle charger offers one of the best ways to charge a battery. Although it generally runs at 1-2 Amps, this type of charger will take a longer time to charge your battery. The best thing about its slow charging process is that it won’t expose your battery to any risks of overheating, overcharging, or exploding due to excess voltage.

Trickle chargers usually take 24-48 hours to charge a 48 Amps deep cycle battery. Due to this slow charging advantage, these batteries are mostly used by mechanics in workshops to keep a battery charged while repairing or maintaining a vehicle.


How Long Can it Take You to Charge a Battery When Driving?


Just as we mentioned earlier, there are many factors that can cause your car’s battery to die. However, once the battery is entirely drained, it can be recharged by using a charger. In most cases, a dead battery can take anywhere from 4 to 24 hours to get charged fully. However, this depends on the size of the battery, its condition, and the amount of amperage a charger has.

Now, there are times when the battery might not be entirely depleted. In such a case, taking a short start-up trip to recharge the battery can solve the problem.

So, how long does it take to charge the battery when driving? In most cases, driving on the highway while maintaining a steady RPM of over 1000 can help to charge the battery in less time. If you’re driving in a high-speed lane, this can take you around half an hour to charge a battery.

On the other hand, if you’re driving on busy traffic lanes, then the time taken to charge the battery can extend to around an hour. Also, the time it takes to charge your battery when driving can extend if you’re using the car’s electronics such as the radio, heater, power windows, and any available entertainment systems.


What if Nothing Works?


Now, in case the battery fails to charge even after using a charger and driving it down the road, the last option you can consider is to jump-start it. Jump-starting a battery is a process whereby you create a temporary connection using an external battery with the hope of transferring current to the dead battery.

Although this strategy works, it’s quite risky, especially among most modern cars, as it can damage the complex electrical systems in a car. For this reason, it’s best if you consult a technician. Most technicians will inspect the battery and the alternator to see whether they’re faulty.


Final Verdict

So, are you still wondering how long it takes to charge a battery? Well, I believe this guide has offered you all the information you need regarding this topic. But, before you get to a situation where the battery is entirely dead, you need to ensure that you turn off all the car’s electronics before getting off.

By doing this, you’ll manage to keep your battery sufficiently charged throughout the night. Also, you need to invest in the right battery charger that will charge your battery fast enough. Lastly, you need to pay frequent visits to a professional technician to inspect the alternator and the electronic systems for any signs of damage.

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