How To Charge A Car Battery (2023 Guide)

Aidan Pounder is a Motor1.com product tester who has written reviews spanning from car insurance to rooftop cargo boxes. He regularly traveled both cross-country and internationally for cycling throughout his youth, having been awarded multiple state titles and podiuming at national championships across several different disciplines of the sport. He spent his more formative years under the hood of a car making sure he could get to his next bike race and knows the best way to secure all of your gear out on the road. His reviews have appeared in major automotive digital publications such as HotCars and Motor1. Aidan brings road trip know-how and a touch of DIY spirit to our team. If he’s not burning through the clutch on his 2003 Ford Focus Zx3, you’ll find him keeping up with the latest happenings in the world of European football.

Whether you take your car maintenance seriously or haven’t been for a tune-up in a while, most drivers will encounter a dead battery at some point. Calling a roadside maintenance service, like AAA, or figuring out how to get your vehicle to a repair shop can be both timely and costly, and is not the perfect solution for everyone.

You can avoid wasting time and money by learning how to charge your own car battery with the following steps.

Disclaimer: Working with car batteries poses risks such as electric shock and potential damage to vehicle systems if improperly handled. Please use caution while attempting any vehicle maintenance and always consult your car manufacturer’s manual.

The first step in learning how to charge a car battery is prepping it to be charged. You’ll need to determine whether or not your car’s battery needs to be removed from its holding tray or if it can be charged as is.

Technically all automotive batteries can be charged while still connected, but it doesn’t hurt to do a quick clean of your car’s battery prior to charging it.

After preparing your vehicle’s battery for a battery charge, you’ll need to turn off your car engine. Then, turn off your vehicle’s entire electrical system, including any interior lights. Confirm that all power is off before progressing to the next step of the charging process.

It is absolutely necessary that you first remove the negative cable and then the positive cable from your battery’s terminals in that order. Otherwise, you may cause an electrical short or damage your car’s battery.

The negative cable is almost always a black cable with a “-” symbol present. The positive cable is typically a red cable with a “+” symbol. To remove each cable, you may first have to remove the plastic caps that are sometimes located on car battery terminals.

For most car batteries, you need to use a 10.0-millimeter socket wrench to loosen the negative cable, while being careful to keep it away from the positive cable as a charge could transfer between the two sources. Finally, repeat the process with the positive cable and terminal while still taking care to keep the two cables separate.

Before charging your car battery, it’s important to clean out your vehicle’s battery terminals. We recommend using a terminal cleaning brush, which is similar to a toothbrush in both shape and appearance. A terminal cleaning brush is used to clean battery terminals by clearing away corrosive debris and chemicals.

A terminal cleaning brush is best paired with a commercial battery cleaning solution, but a mixture of baking soda and water will be just as effective at neutralizing battery acid, preventing corrosion, and thwarting any possible malfunctions. We recommend a ratio of one cup of distilled water to one tablespoon of baking soda.

If you’ve completed the steps above, you’re now ready to connect the car battery charger to your vehicle’s battery. The following instructions will work for most car battery chargers, but if your charger has specific instructions for operation, follow those instead.

To complete the car battery charging process, power off your charger before you touch anything else. Once your car charger is turned off, simply disconnect the positive cable first, followed by the negative cable.

Remember to replace the cables on the terminals of your car battery. Once again, be sure to reconnect the positive cable before the negative one. If you removed the car battery entirely, now is the time to set it back in its tray.

To properly test your car battery, you shouldn’t drive your car for a couple of days after charging. This is because your car’s alternator charges the battery while your vehicle is running. However, this part of the process is not absolutely necessary, as we understand many drivers need their cars on a day-to-day basis.

If you do decide to test your car’s battery, we recommend using an automotive multimeter and following these steps:

Our team also recommends using a battery maintainer to keep your car battery fully charged. These clever devices can be left on and attached to a car battery without fear of overcharging.

Car batteries are finicky pieces of equipment but are absolutely essential as they’re the main power source to make your car run and drive. Even if you purchase a new car, it’s simply luck of the draw whether or not you get a bad battery. Knowing how to DIY and charge a car battery will provide you with the knowledge to get back on the road with just enough power to get home or a full charge for the weeks of driving ahead.

We asked Zac Salerno, a technician at Import Performance, what car owners should consider in order to get the maximum life out of their vehicle batteries.

“If you’re going to be gone for a while, have someone start your car for you if the car’s not going to get started for a couple of weeks,” he said. “I start all my cars once a week if they have their motors together [and assembled]. It’s always good to keep the batteries going because they will die if they just sit.”

“If you disconnect the negative terminal, the battery life will be elongated,” he continued. “But for the most part, as long as you’re driving your car, just double-check the terminals to make sure they’re not super corroded. Just take a toothbrush [and] clean them off real quick. Maybe get some terminal grease or dielectric. Just rub it on there and it’ll be fine for the most part.”

There are two types of battery chargers: standard car battery chargers and trickle chargers. If you’re unsure of where to start looking for products, check out some of our helpful guides where we have performed hands-on testing to ensure the quality of each recommendation.

“Trickle chargers, like the Battery Tender and the Tender Junior – always worth it,” said Kyle Marker, Parts Manager at Leith Lincoln and self-proclaimed DIY car mechanic. “You ask me why? It’s because my Mustang won’t start right now because I [haven’t started] it in three weeks and the battery had 3.6 volts.” A trickle charger, though, would get the job done.

To ensure the accuracy of all the tips and information in this guide, we consulted our network of experts for their thoughts on car batteries. These experts have over 100 years of combined experience in the auto industry, in fields ranging from detailing to accessories to tires, and everything in between. Interviewing experts ensures that all the information and advice we publish is as accurate as possible and delivered in a way that’s helpful and easy to understand.

Our team then combed through dozens of resources such as federal safety studies, research from reputable institutions, verified firsthand accounts, interviews and videos from credible automotive professionals, and our own prior testing conducted by our expert testing team.

Since 2020, we have published over 200 auto product reviews in an effort to make owning a car and shopping for auto products easier. Our team of writers, editors, researchers, and product experts collaborates to thoroughly vet everything we publish. We try to perform in-house testing on real vehicles whenever possible before making our buying and informational guides.

When testing is not feasible, however, our aim is to make your life easier by doing all the online research for you. For more information on our testing methodology, check out our methodology page here.

You can either use a car battery charger to charge a dead battery or connect to a running car battery via jumper cables to charge up a dead battery. If you have an old battery that’s been used for more than three years, it may be time to go get a new one from an auto parts store.

When charging a car battery, you need to connect to the positive terminal first. Then connect to the negative terminal. If you connect to the wrong terminals, you could risk damaging your car battery or even an explosion.

No, a jump starter cannot be used as a battery charger. This is because jump starters are designed to deliver an instantaneous, yet still powerful, burst of electricity to get the car battery turned on. After a battery is jumped, the alternator takes over the process of charging the battery.

*Data accurate at time of publication.