How long does a car need to run after a jump start?
3 Answers
If using a regular charging mode, it typically takes about 12 hours. If relying on the car's own alternator for charging, driving for 1 to 2 hours should suffice. Here are some precautions for jump-starting: (1) The rescue vehicle should turn off its power to prevent short circuits caused by incorrect connections and avoid equipment damage; (2) Use dedicated automotive jumper cables, not homemade ones; (3) When connecting the cables, follow the sequence of connecting the positive terminal first, then the negative terminal, ensuring the positive and negative terminals do not touch; (4) After connecting the jumper cables, promptly start the engine of the rescue vehicle to ensure it has sufficient power; (5) Once the rescued vehicle's engine starts successfully, disconnect the negative terminal first, then the positive terminal to prevent short circuits.
As a veteran driver with 15 years of experience, I usually let the car idle for more than half an hour after jump-starting. The main purpose is to replenish the lost power in the battery, as the alternator can only charge the battery when the engine is running. In winter or if the battery is particularly old, it should be extended to 40 minutes. Last time, my brother's car had a dead battery, and after jump-starting, it only idled for ten minutes before shutting off, resulting in failure to start the next morning. Avoid turning on power-consuming devices like the air conditioner and headlights during the charging process, as this slows down the charging speed. For newer cars with start-stop functionality, it's better to drive out and maintain a steady speed for a few kilometers, as this is more effective than idling for charging and causes less damage to the battery.
I usually drive for 20 minutes right after jump-starting the car. While idling can charge the battery, it's not very efficient. Driving increases the alternator speed, resulting in faster charging. I've encountered many people who only wait ten minutes after jump-starting before turning off the engine, leading to insufficient battery charge and soon being unable to start again. Now that it's hot, pay attention to heat dissipation. In summer, when the car body temperature is high, avoid covering it with a car cover or charging in an enclosed garage. Before removing the jumper cables, check if the battery warning light on the dashboard has turned off. If it's off, it means the charging is normal. If the battery hasn't been replaced for over three years, it's advisable to test its lifespan immediately after jump-starting, as such batteries may not last much longer.
