Now that we've understood the various factors that affect charging times, here are some guidelines on how long the car should be kept running after a successful jumpstart: About 15-30 Minutes: In most cases, the appropriate running time after a successful jumpstart is between 15-30 minutes.
Idling your car to charge the battery does more harm than good. Some people suggest idling your car for 15-20 minutes to recharge the battery, but this is not always recommended. Many modern cars are equipped with sophisticated battery management systems that are designed to help extend battery life.
How Long Does It Take to Charge a Car Battery? After jump-starting your car, it is recommended to run your vehicle for at least 30 minutes, as that's how long it takes to charge a dead battery entirely, or at least sufficiently.
Does revving make a difference? When idling, the engine is still turning at a certain revolution per minute (rpm) – so the alternator is still converting that into usable energy and charging the battery. But revving the car a few thousand rpm faster does actually make the alternator charge the battery faster.
Don't Leave Your Car Idling
Leaving your car running while not moving can strain and drain the battery.
Simply starting a car occasionally and leaving it running for only a few minutes isn't likely to help, in fact this may end up draining a weak battery. Driving the vehicle at 50mph or more for 20-30 minutes would, in most cases, be sufficient to top up the battery charge.
The distance you need to drive to charge a car battery depends on the battery's condition, driving conditions, and the alternator's output. Generally, driving for 30 minutes to an hour at highway speeds can provide a decent charge to a moderately discharged battery.
Our recommendation is to drive around for a while after your jump-start to give your battery time to recharge. Moving forward, make sure to unplug and turn off any battery-dependant systems when you are not driving.
Start the charger and wait.
Depending on your battery charger, it may take 4-8 hours to charge your battery enough to start the car a few times. It may take 10-24 hours to charge your battery up to 100%. The longer you charge it, the more strength the charger can put in the car battery.
You should leave jumper cables connected for around five minutes at first. If your car still doesn't start after five minutes, it may take longer—up to 30 minutes in extremely cold temperatures. If after 30 minutes your car still doesn't start, there's likely more wrong than simply a dead battery.
Most experts recommend driving your car at least once a week for a minimum of 10 kilometers (6 miles) or for at least 30 minutes to keep the battery charged. Any less than that, and your alternator won't have the chance to charge the battery sufficiently.
After jump-starting the battery, if the engine starts and runs normally, and the battery recharges as you drive, it might continue to work as you expect. After a jump start is performed, it's recommended that you run your vehicle for at least 30 minutes to charge the battery fully (or near to full).
Typical Battery Lifespan Unplugged
Typically, you're looking at a lifespan of about 4 weeks to 2 months if your car sits unused. This duration isn't set in stone; it varies depending on several factors, such as the battery's age and whether you've parked your vehicle in extreme temperatures.
Once you've jump started your car, you should drive for at least 30 minutes (in normal driving conditions, not heavy traffic) before stopping to give your battery long enough to build up some charge.
If the battery is completely dead, it won't always have enough power to turn over the engine, even with a jump start. In this case, you'll need to replace the battery to get your car running again. Another reason why a car battery won't jump is because there is a problem with the charging system.
Pumping your gas with the engine running can lead to a fire.
How does this happen? When you grab the pump and start filling up your tank, gas vapors are emitted. Running cars produce a large amount of heat and electricity. When gas vapors run into heat or electricity, they can ignite and cause a fire.
At highway speeds, your engine's running hard enough for the alternator to send spare amps to the battery. But when parked, the engine doesn't have spare amps. No, you can't charge a car battery while idling. At best, it'll charge the battery a few amps, but not nearly the hundreds of amps it took to start the engine.
A jump starter takes less than a minute to jump a car, but it may take several hours to fully charge a car. That's because of its impressive power capacity. It takes between 400 and 600 amps to jump a car, depending on the dead vehicle's engine type, the kind of battery it's used to, and how warmed up the engine is.
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.
A car battery can be charged in the following time: 40 Amps: 30 minutes to an hour. 20 Amps: 2 to 4 hours. 10 Amps: 3 to 6 hours.
Drive the jump-started car for at least 15 minutes.
This is plenty of time to give your alternator and battery time to fully recharge and synchronize. If you haven't used the car in a long time (say, 6-12 months at least), drive for at least 20-30 minutes just to play it safe.
Slow Charging (2-10 Amps): Slow charging is often considered the safest and most effective method for charging a car battery. Setting your charger to 2-10 amps delivers a steady, controlled charge that allows the battery to fully absorb the energy without generating excessive heat.