How long does it take to Charge a car Battery with a 12 volt charger?


The length it take for you to recharge your 12 volt car battery will depend on the amperage of the charger you are using. If you are using a high amp charger then the charging process will be a lot shorter than when using a low amp charger. If you are looking to maintain your car battery at a fully charged level then a low amp is preferable to a high amp charger.

How long to Charge a car Battery at 40 amps

Forty amps will charge your car quickly and efficiently. In fact it will get your battery up to a charge where you can start your car within a few minutes after connecting the charger even if the battery was fairly depleted. These are great chargers to have with you when travelling so as to give your battery the boost is needs when you end up with a depleted battery and help around to give you a jump start using jumper cables.

When using a 40 amp charger you must take care not to overcharge your battery so keeping it connected for long periods of time will damage your battery. If you are using a smart car charger it will reduce the amperage as soon as the full charge is reached from 40 amps down to a trickle just for maintenance or switch off completely once charged, these are the best options to use.

How long to Charge a car Battery at 2 amps

Charging your car battery with a 2 amp car battery charger will take a reasonably long time, up to 24 hours to reach an acceptable charge, this is determined by the fact that your car battery is usually 48 amps and it takes about 1 amp charge per hour on average. This type of amperage is used when using a trickle charger or just maintaining your battery at a certain level and not trying to get a quick charge to boost your battery and get it started.

This is a great amperage to use when you are going to leave your charger connected to your battery for extended periods of time on batteries that are seldom used such as that antique car that is only driven once a month, the trickle charge on a smart charger will maintain the level of charge in the battery so that your car is ready to use when you want to take it out for a spin.

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How long to Charge a car Battery at 4 amps?

A car battery usually holds 48 amps so if you take that it charges at approximately 1 amp per hour you can work out how long it will take to charge your battery with various amperage chargers. Charging your battery with a four amp charger will take about 12 hours to get a full charge out of this low amperage. This is not ideal if you are looking for a quick charge for your car, however it is the perfect charger to use for smaller batteries such as motorbikes or other smaller batteries.

Charging your battery on a low amperage on a smart charge is fine if you are looking to maintain your battery or keep it on a low charge for a period of time. The charger will then charge less used batteries much like a trickle charger and then switch off automatically when the battery is fully charged and switch on again if the battery charge falls below a certain level.

How long does it take to Charge a car Battery with a Trickle Charger

A trickle charger usually operates at around 2 amps and it is going to take a long time to charge up your 12 volt car battery (read our full guide here). It can take as long as 24 hours to get the battery up to an acceptable charge, depending on how depleted your battery is when you start charging.

Trickle chargers are mainly used to maintain your charge on your battery over a period of time so that it never runs out of charge and you are never left stranded with a flat battery. It takes a long time to charge and will switch off automatically in some chargers once your battery is fully charged.

Often trickle chargers are used in workshops to maintain batteries while the mechanic works on the car, especially if the battery is going to stand disconnected for a period of time, this is so that the battery keeps enough charge to be functional when put back into the car for use.


The length of time it takes to charge your car battery is completely dependent on the size or amp of your battery and the amp of the car charger you are using. If using a low amp charger it can take up to 24 hours to charge your battery properly but a high amperage charger such as a 40 amp charger will get the job done adequately in an hour or less, and will get you on the road again in only a few minutes.

About the Author

Bob Robinson has been a tool enthusiast and lawn care expert for the past 11 years. First working with John Deere to reduce their impact on the environment, whilst building his love for writing in his spare time. Now, Bob runs the editorial team at BestofMachinery and tends to his garden in his spare time.

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