How Long Does It Take To Charge A Dead Car Battery?

A very common question often asked by many car owners is, ‘How long does it take to charge a car battery?’. Well basically, for a 12V battery to be fully charged, the time depends on your charger’s amperage. A charge with high amps takes less time for charging the car battery compared to one with lower amps. Meanwhile, using a low amp charger is better than using a high amp one in order to maintain the car battery at a fully charged level.

Let’s take a closer look into the details, to understand exactly how much time does it take to charge a car battery.

How Long Does It Take to Charge a Car Battery at 40 amps?

If you want a very quick and effective charge for your battery, a 40 amp charger is a great option. If your battery is absolutely depleted, even then your car can start in just a matter of a few minutes when connected to the 40 amp charger. This charger is very useful to be carried while traveling as well, as your depleted battery can be charged very rapidly with it and also helps around to provide a jump start with jumper cables if you are stranded.

Note: Note that keeping such a charger connected for extended periods will harm your battery a lot. If you are using a smart charger, the amperage will be decreased automatically going down from 40 amps to a trickle for switch off completely, as soon as your battery is charged fully.

Hence, the best choice to buy is this smart charger.

How Long Does It Take To Charge A Car Battery at 4 amps?

A deep cycle battery usually holds 48 amperes, which means that it will take approximately 48 hours when charging at 1 amp. Similarly, it will take 12 hours to charge the battery fully when charging it at 4 amps. Hence, for quick charging, a 4 amp charger is not a smart choice for you and is a better option for smaller batteries.

If you wish to keep your car battery at a low amperage for longer time periods or wish to maintain it, a 4 amp charger is a great option. It will work like a trickle charger and switch off automatically once the battery is fully charged, then switch on again as the battery level drops below a certain fixed level. 

How Long To Charge A Car Battery At 2 Amps?

It will take a lot of time to charge a car battery using a 2amp charger. The average time to charge a 48amp battery fully, using such a charger is 24 hours. Hence, it is usually used as a trickle charger to maintain the battery at a probable charge rather than getting a fast charging boost for the battery to get it started.

If you are planning to keep your battery connected with the charged for a long time period on batteries which are used seldom like those in an antique vehicle which is driven just once in a while, a 2 amp battery is a great choice.  A smart 2 amp charger also helps maintain the charging of a battery at a specific level to keep the vehicle ever ready for a drive when you wish to take it for a spin!

How Long Does It Take To Charge A Car Battery With A Trickle Charge?

If you are planning to leave the car in your garage for a longer time, a trickle charger is a great choice. These chargers usually run at 2 amps and may take around 24 hours to get a 48 amp battery charged to a certain level, according to the battery’s health.

Battery maintenance is the primary function of a trickle charger as it helps keep the battery charged always. It requires a long time to charge the battery fully and will then switch off automatically once the battery is fully charged.

Trickle chargers are often used by mechanics at workshops to maintain the battery of a car as they perform repair or maintenance jobs on other parts, especially when the battery will remain detached from the vehicle for a long time so it has enough charging once it is attached for use again.

How Long Does It Take To Charge A Dead Car Battery?

Another question asked by car owners is that how long does it take to charge a dead car battery? A dead car battery takes anywhere between 4 to 24 hours to be charged fully. The time varies according to the amperage and size of the battery. Usually, a common rate for car battery chargers is a 4 amp one, and a dead 52Ah battery will need at least 10 hours to charge fully. However, after one hour of charging the car will be able to start.

Recovering a Dead Car Battery:

If you wish to recover a dead car battery, follow the steps below to do so.

  1. Check the car battery charger you will be using and its amperage. Chargers with higher amperage will charge the battery much faster than low amp ones. Nevertheless, as mentioned above that a low amp charger is always considered better to maintain the battery over a longer time period.
  2. Check the size and type of your car battery. A medium-sized car uses a battery between 40 – 80Ah. Moreover, a GEL/AGM battery will be charged much faster than a regular wet battery.

Also note that your car battery can be charged rapidly using a 40amp charger, but the battery will be destroyed if you forget disconnecting the charger. There are 40 amp smart chargers as well in the market, so if you are looking for a quick charge, go for those.

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

Charging a car battery is something that shouldn’t be overlooked at any time, and this is why it becomes very important to charge the car battery as needed. It can be recharged simply by driving as well, but how to do so? Let’s have a look.

1. Car Usage Cycle

Your car usage cycle is among the very key factors which will provide to the battery drainage. If the car is left unused for extended periods, the battery will potentially start to dry out. Moreover, if the car’s AC or lights are switched on overnight accidentally, the battery drains out then also.

Idling is the best way to charge your car battery in such cases. If there is no fault with the alternator, the idling process will partly recharge the battery. You can also go for a short start-up trip alternatively, to recharge your battery.

It should however be noted that these methods do not truly charge the battery and you will still need to use a multistage battery charger to ensure apt charging of the battery up to optimal levels. Let’s look over this further and see how long does a battery takes to charge when driving.

2. The Initial Charge Time Duration

The time for car battery recharging depends greatly on when was it recharged the last time. There are variations depending on each vehicle that how long will it take for a car battery to charge fully while driving. An RPM of more than 1000 should be maintained generally for a specific time. The lesser the battery would already be charged, the greater the time it will take for it to recharge. You may also refer to some maintenance tips for top car batteries in the year 2018.

It is shown by statistics that when driving on high-speed lanes, half an hour is required to charge the battery. Meanwhile, it may take up to one hour or even more when driving on busy traffic lanes in the city. Do not use lights, heater, a stereo system, radio, or any other electric device when driving intending to charge the battery.

3. What If Nothing Works Out?

If idling or running on the road does not work to recharge the battery or if the battery has gone dead, you need to jump-start it. Thus, it is always better to consult a technician in such a case. A temporary connection is created with the external source of battery to transfer the power to the dead battery.

When the vehicle starts with this jump-start mechanism, it will switch back to its natural methods of recharge. There may be times when there is a fault in the alternator. In such a case, you should visit a mechanic or technician to ensure the battery and alternator are working efficiently.

Frequently Asked Questions – FAQs

1. How Fast Should I Charge My Car Battery?

Your needs decide the charging speed – if you are looking for a rapid charge, use a high amp charger but remember that some chargers can damage the battery as well. A long time is needed with low amp chargers to provide a full charge to your battery, although they are the best option to maintain the battery for an extended time period.

4-15 amperes are given out by a regular car battery charger, while 2-4amp chargers are usually for the purpose of battery maintenance and can take up to 24 hours for a dead battery to be fully charged. If you wish to charge the battery rapidly, it is recommended to use a smart high amp charger which allows for quick charging while imposing no damage to the battery.

2. When is Jump Starting a Good Idea?

If you want to start the car quickly, a jump starter is highly recommended. The car will be started right away using a modern jump starter which is very safe and user friendly.

3. What Car Battery Charger Should I Use?

To determine the type of charger best for your car battery, determine the amp rates you need in a charger. There are many smart chargers available today which can be used easily and turn off or on into the maintenance mode automatically once the battery is charged fully.

A greater amp supply is provided by cheaper chargers, compared to what is written on their boxes. Therefore, it is recommended to always get a high-quality charger from an authorized manufacturer and dealer only. This will not just save your car battery but will also minimize the damage risk for your car.


As we have discussed how long does it take to charge a car battery in detail, you will not face any problem with it the next time you go for a charge. Remember that no electrical device on your car should be left turned on when it is not needed, and the car should be running every now and then to avoid its battery from draining.