Jump starter is a portable power pack that gives a boost of energy to your car to “jump-start” or “boost start” a car with a dead battery. Jump starter put any energy into your car battery directly, but gives that power to the starter motor of your car and spins it to crank the engine.
There is a lot of misconception about charging a battery with a portable jump starter. The clear answer is: No, A jump starter does not charge your car battery but helps your car (with a weak or a dead battery) to spin the starter motor and start your engine. Then the car’s alternator (a small electricity generator connected to the engine) will put some electric juice back into the car battery.
How long should you let your car run (after jump starting) to let its battery get charged?
After a successful jump-start (either with a portable jump starter or the jumper cables), you should at least let your car’s engine run for at least 10-15 minutes to charge the car’s battery. Revving the engine a little bit (about 2000-2500 RPMs) helps too.
After letting your car run for 10-15 minutes, shut it off for 20-30 seconds to settle the floating charge of the battery. Then try to start your vehicle again.
If your car starts without a problem, then your battery is still good, and you do not need to replace it anytime soon.
Now before I get into the next segment I’m suggesting an article on whether a car battery can recharge itself.
Why do I need to let my car sit running to charge its battery?
Whenever you turn on the headlights, turn signals, windshield wipers, or even the radio to listen to your favorite track, your car battery is used to power all these electronics.
Your car also has a small electricity generator that produces around 14 volts to charge your car battery back, so it does not get fully depleted. The alternator only generates electricity when the car’s engine is running.
After a successful jump-start (assuming you have a fully charged working jumpstarter), you need to charge your car battery back up fully so that it has enough juice to start your car the next time. That is why you let your car run for the alternator to generate electricity and put it back in your battery.
All the batteries are consumable products, and they all eventually die. The life of a car battery depends on where you bought it from and the manufacturer.
All lead-acid batteries have a shelf life (usually 4 to 5 years), and after that time has passed, you can not bring the battery to life no matter how much you charge it.
After jump-starting a car and letting it run for around 10-15 minutes, you go to start it again, and the car cranks slowly or not at all. It is time for a new car battery.