How Long Will it Take To Charge a Dead Car Battery?

For many motorists, waking up one morning and going to start their car only to have nothing happen is the start of their worst nightmare. No engine noises, no sputter, just, nothing. If that happens to you then there’s a good chance that your car battery is completely dead.

If you’ve thought ahead, you’ll have a car battery charger on hand in your garage, but how long does it take to charge a dead car battery, and would you know where to start?

Taking Care of Your Car Battery

Recharging a dead car battery can take at least 4 hours, and even up to 24 hours depending on the power of the charger and the size of the battery. Usually, battery chargers put out around four amps, but there are more powerful chargers out there.

The good news is that you don’t have to fully recharge the battery in order to start your car. If you’re in an emergency situation, you can get enough juice with about an hour’s worth of charge from a standard charger.

Are Fast Chargers Worth It?

Higher ampere chargers can charge the battery faster and can be handy if your car’s battery has gone completely flat. The problem is that they can damage the life of the battery if you use them all the time.

If you need to start your vehicle quickly when the battery is dead, rather than using a fast charger the better choice is a jump starter. Modern jump starters are far safer and more user-friendly than the jumper cables that you might remember from a decade or so ago. 

They usually have safeguards so that you can’t connect them with the wrong polarity. They’re now a convenient and safe way to get going if things go wrong.

Choosing a Car Battery Charger

You get what you pay for when you buy a battery charger. Avoid the cheaper, off-brand models because they often lack monitoring features, and they are likely to put out fewer amps than they promise.

Look for a high-quality 4-8ampere charger for a mid-sized car battery, and pick up a jump starter for when things go wrong.

Why Do Batteries Fail?

So, now you have an idea of how to get your car going again when the batteries fail. You may be wondering why your battery died in the first place. There are a few things that can make your battery fail:

  • Leaving the headlights on will kill the battery fairly quickly. Most modern cars have an auto shut-off for the headlights, but older models may lack this feature.
  • Using the in-car features can also kill the battery. If you spend a lot of time sitting in the car with the AC on and listening to the radio then your battery may drain faster.
  • Charging failure is another common issue. The battery should be charged while you are driving, but if you rarely drive long distances it may not get charged by the alternator.

Extending Your Car's Battery Life

You can maintain your car’s battery by using it for longer trips. If you don’t have a lifestyle that necessitates this then you should use a battery charger with a voltage monitor.

Another issue that can damage the battery is vibrations. If your battery is not kept securely fastened in the housing then vibration could damage the internal components, and this could cause damage to the battery by creating short-circuits. Refastening the battery ensures that this doesn’t happen.

Keeping the battery clean and dry can be useful, because it will prevent the terminals from corroding. If you have rusty terminals then the battery will take longer to charge because the current won’t conduct as well as it should. Disconnect the battery, clean the top, and scrub the terminals using a toothbrush that has been dipped into a mixture of baking soda and water. Remove the mixture by spraying cold water onto the terminals, then dry the battery with a clean cloth to prevent future corrosion.

Regular maintenance will help to make sure that the battery lasts as long as possible. Take care, when cleaning the battery, not to get acid onto your skin, because it can be a nasty irritant. If it does get onto your skin, rinse it off with cold water as quickly as possible.

Conclusion

If your car battery is dead, use a standard 4-8 amp charger to fully recharge it. As we said before, this process takes around 4 hours. However, charging the battery for 1 hour in sufficient to drive on.

Get into the habit of double checking that you turned everything off before you leave the vehicle. Even if your car has an auto shut-off for the headlights, it’s a good habit to make sure that everything is off.

The Vehicle Lab
Sign up for our newsletter to get new reviews each week.

Leave a Comment

By clicking "Accept All Cookies," closing this banner, continuing to navigate this site, or clicking a link you agree to the storing of first and third-party cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts.