How long does it take to charge a car battery?

Posted by Jayme Sauer on Mar 25, 2024 10:00:00 AM

The time it takes to charge a car battery depends entirely on the kind of battery you have and the method of charging you use. In this blog post we will discuss the charging differences between SLI and EV batteries.

Charging SLI Batteries

The term SLI refers to starting, lighting and ignition. SLI batteries are normally smaller in stature than industrial batteries. These types of batteries are designed to start, run and maintain a power source to their particular application. SLI batteries are used in a variety of vehicles such as cars, trucks, RVs, boats, motorcycles, ATVs, and other powersport applications. Because SLI batteries are starting batteries, they are recharged by the alternator in the vehicle. 

Your vehicle's battery provides the large current required to start the engine, and then the alternator assists by providing the power to run your vehicle's electrical systems. As the alternator rotates, it creates a DC voltage that charges the battery. While your alternator does charge your battery, it only charges it while you're driving highway speeds and takes a very long time to charge significantly. If you want to give your battery a bit of a boost, make sure to regularly incorporate 20-30 minutes of highway driving into your routine.


If your battery is "dead" or below the number of volts necessary to start your vehicle (usually above 12V) you may need to use an external battery charger or battery maintainer.  

Depending on the Depth of Discharge (DoD), it could require 4-8 hours to charge the battery sufficiently for starting your car a few times. However, achieving a full 100 percent charge may take anywhere from 10 to 24 hours. The longer the charging duration, the greater the amount of power the charger can impart to the car battery.

A battery maintainer is essentially a small charger that sends small amounts of voltage to your battery. These are often referred to as trickle chargers. Typically charging at around 2 amps, it can take as long as 24 hours to charge a fully dead battery. These chargers are great for batteries that sit without use for long periods of time, and can also help reduce the wear and tear of you regularly-used SLI batteries.

Charging EV Batteries

Unlike SLI batteries, EV batteries are primarily charged by an external electricity source. It can take as little as 30 minutes or more than 12 hours to charge depending on the size of the battery and the speed of the charging points; the bigger your car's battery and the slower the charging point, the longer it will take to charge. 


For a typical electric car with a 60kWh battery, it takes around 8 hours to charge from empty to full with a home charging point with a power rating of 7kW. With a rapid charger (43-50 kW and 150 kW), EV batteries can be charged in two hours or less.