In everyday life, long-distance driving in an electric vehicle may completely drain the battery, while short-distance driving can lead to partial discharge. To better plan your trips, you might be wondering: how long does it take to charge a car battery? Today, let's take a closer look at different battery discharge scenarios, how long it takes to fully recharge, and how to choose the right battery charger.

Usually, the most common cause of a dead battery is complete discharge. However, there are other reasons as well, such as parasitic drain, accidentally leaving interior or headlights on, or simply using an old battery.

Factors that affect charging time

When your car battery is low or completely dead, several factors can affect the charging time, including:

1. Battery Capacity: Measured in amp-hours (Ah), a larger capacity battery will take longer to charge. 

2. State of Charge (SoC): The current charge level of the battery. A completely dead battery will take longer to charge than one that is partially charged. 

3. Charger Output: The amperage output of the charger. Higher output chargers can charge batteries faster. 

4. Battery Type: Lead-acid, AGM, and lithium-ion batteries have different charging requirements. 

Understanding the factors that affect car battery charging can help you better estimate how long it will take to fully recharge your battery.

On average, it takes anywhere from 4 to 24 hours to fully charge a car battery. The exact time depends on the battery’s capacity and the charging amperage. Most car battery chargers deliver around 4 amps of current.

For example, if you have a 50Ah battery that's completely dead, it would take about 12 hours to fully charge it. This is calculated by dividing the battery capacity (50Ah) by the charger’s output (4A), giving you the estimated charging time in hours.

Car Charger Typical Charging Times 

If you're using a different charger, you can estimate the charging time more accurately based on the charger's specifications.：

For a standard 12V car battery (around 50Ah): 

1. Slow Charge (2A charger): Approximately 25 hours. 

2. Medium Charge (10A charger): Approximately 5 hours. 

3. Fast Charge (20A charger): Approximately 2.5 hours. 

Of course, the calculations for charging time mentioned above are just general estimates, as charging time also depends on the battery’s performance and the surrounding environment. If you really want to know the exact charging time for your car battery, we suggest considering two scenarios:

Ideal Standard Conditions: In this case, you can calculate the charging time based on the current amperage, charging rate, and your charger’s specifications.

Real-World Usage: For your specific charging situation, you can observe and record the charging time over time, taking into account your own usage habits. You can then compare your findings with the standard charging time for a more accurate estimate.

When it comes to safe and fast charging, we recommend our efficient and safe smart car chargers. We have a wide range of models in stock, and if you can’t find the one that suits you, our customer service team will be happy to help.。

FAQ

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

With a 4A charger, it takes about 12 hours. A 6A charger cuts it down to around 8 hours. Basically, the more amps, the faster the charge.

Can a completely dead battery be recharged?

It depends. If the voltage isn’t too low for the charger to detect, you’re good. Just charge it slowly overnight to be safe.

Does a car battery charge while idling?

Yes, but it’s pretty slow. You’d need to keep the engine running for hours to get a decent charge.