How long does it take to fully charge a car battery while idling?

Faster speeds generate more RPMs, so your battery will recharge faster at speeds of 55 MPH or higher. It takes most vehicles about 30 minutes of driving at highway speeds to fully recharge the battery. Keep in mind that 30 minutes is an average.
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How long should you idle a car to charge the battery?

  1. Remember: After you've done a jump start, you'll need to keep the vehicle's engine running for around 30 minutes to allow the alternator time to charge the battery sufficiently.
  2. Remember: If your battery is still losing charge after you've done this, it may be that you need to replace it.
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Will letting a car idle charge the battery?

The short answer is yes, but, it may take several hours to fully charge your battery wasting fuel. You also run the risk of having your battery discharge at idle speeds.
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Does revving engine charge battery faster?

The battery will charge faster if you rev the engine faster. Why? Because the faster the crankshaft turns, the faster it turns the belt that runs the alternator. And the faster the alternator turns, the more electricity it produces to run all the electrical stuff in the car — and recharge the battery.
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How long should a car idle after jump start?

After getting a jump, you should leave your car running for at least 30 minutes. For more reliable results, drive it around instead of letting it idle. This should fully charge the battery so it won't die on you again.
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Will my car battery charge if I leave the engine running?



How often should I run my car to keep the battery charged?

To keep your battery adequately charged, we recommend driving the vehicle once a week for at least 30 minutes, preferably at highway speeds to ensure that the battery gets the boost it needs.
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How do I know when my car battery is fully charged?

Fully charged automotive batteries should measure at 12.6 volts or above. When the engine is running, this measurement should be 13.7 to 14.7 volts. If you don't have a multimeter to tell you the voltage of your battery, you can do a test of your electrical system by starting the car and turning on the headlights.
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How long does a 12v battery take to charge?

A 12-volt battery could take up to 12-24 hours to charge fully. When recharging your battery, remember that if it gets too hot while you're charging it, you need to stop charging. It should not get too hot above 125 Fahrenheit. Ideally, slow charging your batteries is the best option.
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How do you tell if a 12-volt battery is fully charged?

A fully-charged 12-volt battery, allowed to “rest” for a few hours (or days) with no load being drawn from it (or charge going to it), will balance out its charge and measure about 12.6 volts between terminals. When a battery reads only 12 volts under the above conditions, it's almost fully depleted.
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How long does it take to charge a car battery with a 12-volt charger?

Charging times with different battery chargers

2 Amp charger: 24 to 48 hours. 4 Amp charger: 12 to 24 hours. 10 Amp charger: 3 to 6 hours. 20 Amp charger: 2 to 4 hours.
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How long can a car sit before the battery goes dead?

Typically, your car can sit about four weeks to two months without driving before the battery dies. The reason your car can sit only for so long before it dies is the fact that your car battery is in use even when you're not behind the wheel.
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How do I keep my car battery from dying when not in use in winter?

Tricks for Keeping Your Car Battery Charged in Cold Temperatures
  1. Park your car in the garage, away from the wind. ...
  2. Pause before turning on accessories. ...
  3. Juice it up! ...
  4. Keep your battery free of dirt and debris. ...
  5. Get your battery checked before winter hits.
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How long does it take an alternator to charge a battery?

Generally, if you can keep your engine RPM up, your alternator will charge your battery at a faster rate. If you are driving on a motorway, you should be able to charge your car battery in 30 minutes. If you are driving in the city, it may take an hour or more.
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What should an alternator charge at idle?

Most alternators that are charging properly should produce a voltage of about 13.8 to 14.2 volts at idle with the lights and accessories off.
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Will alternator charge a dead battery?

A) Alternators are designed to maintain a battery's charge, not to recharge a dead battery. Charging a dead battery with an alternator will result in premature alternator failure.
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Will warming up a car battery help it start?

“Because a warm battery will start the car much better than a cold battery,” he said. “All you're trying to do is retain the heat in the battery that you've generated by letting the engine run.”
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How often should I start my car to keep the battery charged in cold weather?

If you plan on not using your car for an extended period of time during snow season, it is important to turn it on every 6-12 hours and let it run idle for 15-20 minutes so that it reaches operating temperatures. This provides current to the battery, allowing it to regain its charge.
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Do I need a new car battery if it dies in cold weather?

A car battery can die in cold weather if corrosion is not cleaned off. If the problem is too severe to simply clean it off, you need to get a replacement battery.
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Does a car battery lose charge when not in use?

That's why batteries lose their charges as they sit. If the battery is connected to your car, it drains even faster because your car sucks power even when parked – especially if it has an alarm system, on-board computers and memories for seat positions and radio and climate control settings.
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How do I charge my parked car battery?

The best way to really charge your battery is by taking a few laps. Car experts say that you want to drive around 30mph for around 30 minutes. This seems to be the most efficient way to get your alternator churning and cranking electricity back into your battery.
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Is it better to charge a battery at 2 amps or 10 amps?

You would use 10 amperes on a car battery and 2 ampere on whatever small batteries you might want to charge that still use the same voltage. For example, a motorcycle battery could use the 2 ampere charging option.
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How long does it take to charge a 12 volt battery with a 10 amp charger?

A 10 Amp charge will take 4-7 hours to fully charge the battery, a 2 Amp charge will take 1-2 days. You don't need to charge the battery to start the car.
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How long should I charge a dead car battery at 10 amps?

Typically, a 10 amp battery charger will take approximately four to 11 hours to fully charge your car's battery. However, you don't have to fully charge the battery in order to start the car.
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How long does a trickle charger take to charge a 12v battery?

If your battery is completely dead, it will take a 1-amp trickle charger 48-hours to recharge it fully; meanwhile, a 2-amp trickle charger could do it in 24-hours.
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What happens if you leave a car battery charger on too long?

A: If you leave the charger connected continuously, even at a mere 2 amps, the battery eventually will die. Overcharging a battery causes excessive gassing — the electrolyte gets hot and both hydrogen and oxygen gas are generated.
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