How to safely and quickly recharge a dead car battery

Whether you’re on the road or still in your own driveway, realizing your car battery is dead is always an inconvenience. The risk of finding yourself with a dead battery is higher in the winter, since the cold temperatures can be very harsh on your vehicle.

If you end up with a dead battery, whatever the season, follow these tips to safely recharge it.

How to safely and quickly boost car battery - comment recharger une batterie a plat rapidement et en toute securite
  • Difficulty: Easy
  • Duration: 10-30 minutes
  • How often: As needed

What Causes a Dead Battery?

Many things can lead to a dead battery, including the following:

  • Loose or corroded battery connections
  • Extremely hot or cold temperatures
  • Taking too many short trips
  • Leaving the lights on for too long

Many of these causes can be avoided, especially with proper maintenance. But a dead battery isn’t always preventable. Thankfully, unless it’s severely damaged, it’s easy to get your battery up and running again.

Inspect the Battery

The first thing you need to do is inspect the physical appearance of your battery for signs of damage. Always wear gloves when doing this.

If you notice any cracks or leaking battery acid, do not attempt to recharge it. If you see some corrosion but the rest of the dead car battery looks okay, start by cleaning it with battery cleaner and a battery terminal brush. Once the battery is cleaned off and its cables are secured, you can jump-start your vehicle.

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How to Jump-Start Your Car

Before you can recharge your dead car battery, you need to jump-start it. Follow these steps:

  1. Position a functional vehicle next to the one with the dead battery. The vehicles should be close enough for the jumper cables to reach between them without the vehicles touching each other.
  2. Turn off the car with the functional battery.
  3. Open the hood/compartment on each vehicle where the battery is located.
  4. Connect one end of the positive jumper cable to the dead battery, then connect the other positive end of the cable to the charged battery. The positive and negative terminals on the battery will be indicated by plus (+) and minus (-) symbols.
  5. Connect one end of the negative jumper cable to the negative terminal on the charged battery and the other end of the cable to a grounded metal component on the car with the dead battery, like the frame or chassis.
  6. Turn on the car with the charged battery.
  7. Leave the cars connected for at least five minutes.
  8. Try starting the vehicle with the dead battery. If the battery has enough power, it should start without any problem. If the vehicle doesn’t turn on, wait another five minutes before trying again.
  9. Once the car with the (previously) dead battery turns on, disconnect the jumper cables in the reverse order you connected them:
    1. Remove the negative cable first by disconnecting the grounded end from the frame or chassis, then the other end from the negative terminal on the battery. Next, remove the positive cable by disconnecting it first from the car that supplied the boost and then from the previously dead battery.
  10. Let the car that had the dead battery run for at least another five minutes before moving on to the next part of the charging process.

What Condition Is It In?

After jump-starting your vehicle, determine how dead the battery is before you try to fully recharge it. You can do this with a voltmeter or multimeter.

A healthy battery should read between 12.4 and 12.7 volts. Your battery’s voltage will determine how you should charge it after jump-starting your vehicle.

Above 12 Volts

If your battery is between 12 and 12.4 volts, you can recharge it using your vehicle’s alternator. Simply drive around while using as little electricity as possible. That means no stereo, no lights (don’t do this at night), and no heating or A/C. Conserving electricity this way will send as much energy as possible directly to the battery.

Avoid idling when using this charging method. After a 30-minute drive, your battery should be sufficiently charged for next time you start up.


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Below 12 Volts

If the battery reads below 12 volts, it’s considered “discharged.” Driving around can’t revive a battery below 12 volts, and attempting to do so might damage the alternator.

Instead, connect the battery to a jump starter or battery charger either before or right after doing a jump-start.

Using the appropriate method to recharge a dead car battery is crucial to bringing your battery back to life safely. If you recharge your battery incorrectly, it may end up dying again or failing completely. If you have any concerns about recharging your battery yourself, ask for help at a NAPA AUTOPRO service centre.

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Changing Your Battery

With proper care, most car batteries last four to five years. Be aware of the symptoms of a failing battery. When it’s time for a new one, follow this guide on how to replace your battery.

For more information about recharging a dead battery, visit your local NAPA Auto Parts store to speak with an expert.

6 Replies to “How to safely and quickly recharge a dead car battery”

  1. Wow, superb blog structure! How lengthy have you been blogging for? you made running a blog look easy. The full glance of your web site is great, as well as the content!!

  2. jorden765 says:

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  3. Eve Mitchell says:

    It’s good to know that you can’t recharge your car battery by letting it run if it is below 12 volts. I would like to get my car battery tested this month to see how it is performing. It’s an old battery, so I want to make sure that it’s still up to par.

  4. John Gleason says:

    If the battery is fully discharged ( like if something stayed on overnight) your battery charger may not work. If so, and you can’t connect directly to another car’s battery, you can remove the dead battery, take it to the other car, and jumper it there. After about 5 minutes, remove the jumper cables and the charger should work.

  5. Alex says:

    Well written and very informative. Very easy to read and understand for layman. For additional signs and symptoms to look out for for a failing battery, can refer to the article here

  6. AGM says:

    Great content, it will help in my business Thanks for sharing useful information. Respectfully, David, author of the blog

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