Skip to main content
  1. Home
  2. Auto

How to charge a car battery safely and efficiently

By
Image used with permission by copyright holder

It doesn’t really matter if you’ve waxed your car to its glossiest threshold, or you’ve upgraded its sound system to the latest speaker model with excellent bass level. When you’re commuting, renting a motorhome for a road trip, or out and about doing errands, the basics matter the most. A dead car battery can be a nuisance to add to your schedule. This problem can stem from many different reasons, including leaving your car in freezing temperatures, keeping the interior lights or headlights on while the car engine is off, and going for long periods without starting your car. Replacing the battery is usually the first course of action, but recharging it proves to be the best solution in most cases.

If you ever find yourself in a dead car battery situation, fret not. As stressful as it may sound, recharging a battery only requires very little in terms of car maintenance and mechanical experience or tools. Read on and find tips on how to get your car battery up and running safely and efficiently.

Recommended Videos

Preparing to charge the battery

Your safety is of the utmost importance when it comes to working on your vehicle. Equipping yourself with the proper gear is the first step to charging your car’s battery. Use protective eyeglasses to shield yourself from sparks, fluid, or any falling material, as well as gloves to safeguard your hands from possible pinches and cuts. Keep children away from the area while you work.

Related

Additionally, you’ll need to identify the type of battery you have and its voltage in order to charge it properly. These details are usually written on the battery itself, but if not, you may have to check the manufacturer’s website. Common types of batteries include wet cell and Valve Regulated Lead-Acid Battery (VLRA), which come in the form of Absorbed Glass Mat or Gel Cell batteries.

Charging the battery

Through a battery charger

One of the easiest ways to juice up your car’s battery is by using a portable charger. It’s a standalone device that connects to the car’s positive and negative battery terminals. There are different models available on the market, but most types offer quick-charge and jump-start modes, which are perfect for speedy battery charges. Other charging modes include trickle, lower power, and long-term charge, which are designed to safeguard batteries and keep them in tip-top shape.

After you’ve decided what mode to use for your car battery, turn on the charger, and let it do the work. Charging time can be as fast as 15 minutes to several hours, depending on the mode. Some chargers have an indicator light built into them, so you’ll know exactly when the battery is fully charged. Newer digital chargers even pack a microprocessor inside, which monitors how much the battery has charged, and then automatically stops the process when charging is complete.

Through jumper cables

Another common way to recharge a battery is by jump-starting it. This method is especially perfect if you are away from home or don’t have a portable power source. Jumper cables are used to supply power to a dead battery through a functional battery from another car. Before doing this, make sure the dead battery is intact and doesn’t have any visible acid leaks or cracks. Turn off all accessories and lights as well to avoid causing the battery to arc while it’s being charged. You may also opt to clean the terminals to ensure a stable connection on both batteries.

Avoid mixing up the connection of the terminals and cables, as this could lead to damage or a fire — positive ends are for positive terminals and negative cables are for negative terminals. Also, do not let negative cables droop into the engine bay where they may possibly touch metal, which can serve as a ground to complete the circuit.

Once the cables are securely connected, start the functioning vehicle, and allow its electrical system to juice up the dead battery. The longer the battery has been dead, the longer it will have to be charged for it to start. Keep it running for a few minutes before trying to start the other vehicle.

If the vehicle dies after disconnecting it from the functioning car, check to see if the battery is connected properly. If the car starts and runs well, disconnect the jumper cables, but don’t turn off the engine right away. Continue running it for a bit, or take it for a short drive to give its alternator a chance to thoroughly charge the battery.

Other tips

Using a battery charger or jump-starting did not work? Remove the battery and have it checked by your local auto parts store to know if it can be serviced or needs to be replaced. You may also want to check the alternator. A faulty alternator may be what’s preventing the battery from charging sufficiently.

Editors’ Recommendations

21Oak Contributor
21Oak Contributor
Former Digital Trends Contributor
John Clay Wolfe is auctioning off 42 museum-quality cars on Dec 18th
GMTV's John Clay Wolfe auctioning off 42 premium cars
1953 Corvette

Whether it's finding a $20 bill in an old coat, unearthing a diamond bracelet on a sandy beach, or discovering 42 museum-quality classic cars in the middle of nowhere, there is nothing like uncovering buried treasure, which is a feeling the president and founder of Give Me The Vin is familiar with. Just a year ago, John Clay Wolfe made a barn find that would make any car enthusiast green with envy and would have been impressive enough for one lifetime.

In yet another stroke of unbelievable luck, or incredible research, Wolfe uncovered a treasure trove of 42 rare cars that are almost all in unbelievably excellent condition. He is selling the entire collection in his personal Manheim Dallas arena on December 18th, aptly dubbing it John Clay Wolfe's Classic Christmas Miracle auction. While we don't have space for all 42 cars, the following are a few of our favorites.

Read more
NHTSA issues ‘Do Not Drive’ warnings for certain cars made with Takata Airbags
Do not drive these cars made with Takata Air Bags
vehicles driving on the highway

While we've seen a good number of significant recalls as of late, none compare to the infamous Takata airbag recall, which has been called “the largest and most complex safety recall in U.S. history" by the National Highway Traffic Safety Administration. A total of 67 million airbags have been recalled, spanning 42 million separate vehicles from 34 different brands and 19 separate auto manufacturers.

According to the NHTSA, the Takata airbag problem has caused 27 fatalities and over 400 separate injuries. While the safety administration says that about 88 percent of the airbags in question have been either replaced or repaired, that still leaves a significant number of cars, along with their drivers and passengers on the road, still at risk of injury and potentially death.

Read more
These are the most reliable new cars for 2025, according to Consumer Reports
Consumer Reports' most reliable cars
Subaru Forester

While many of us start our new car shopping with a car we happen to think looks good, it is essential to remember that today, the average cost of a new car is over $48,000. For most people, that is a sizeable investment that will be stretched over several years and should not be taken lightly. As with all significant investments, it should be thoroughly researched beyond what our neighbor or coworker says about their car.

Thankfully, Consumer Reports has done the heavy lifting for all of us, reaching out to owners nationwide. They gathered data on 2020 to early 2025 model years, totalling more than 300,000 vehicles. CR took twenty typical problem areas, ranging from cheap interior trim pieces breaking to engine and transmission maladies that can tally up to thousands of dollars to replace or repair. The scores for each area are weighted according to severity and cost, and the total of those areas results in each vehicle's Predicted Reliability Score.

Read more