Can the battery be charged when the vehicle is started but not moving?
4 Answers
After the car is started, the battery can still be charged even if the vehicle remains stationary. As long as the engine is running, the generator will automatically charge the battery at idle speed. Once the engine is successfully started, it is charging 100% of the time. Moreover, the charging power is sufficient not only to charge the battery but also to continuously supply electricity to other loads in the vehicle. At idle speed, the voltage output by the rectifier regulator is generally above 13 volts. Other precautions for car batteries: 1. Do not leave the car unused for extended periods: If the car is not used for a long time, such as twenty days or a month, the battery cable should be disconnected, or the vehicle should be started and driven for several dozen kilometers every two weeks to ensure the battery remains functional. 2. Avoid frequent starting of the vehicle: In winter, it may be difficult to start the car. Many people tend to start the engine repeatedly, but the correct approach is: each attempt to start the engine should not exceed 3 seconds.
I've been driving long-haul trucks for nearly ten years and this situation is quite common. It's true that leaving the vehicle idling after starting can charge the battery, because once the engine is running, the alternator kicks in and sends current back to replenish the battery. However, this method isn't very efficient—it charges extremely slowly, essentially operating at idle speed where the charging rate is far lower than when driving at normal speeds. Plus, it consumes quite a bit of fuel, and sitting in the car waiting just wastes gasoline. My advice: if the battery is temporarily dead, a quick emergency charge of half an hour is enough—don’t exceed an hour to avoid overheating the alternator or accelerating battery aging. Develop good habits like checking if lights are off before leaving and taking regular medium-short trips to keep the battery active, which can prevent a lot of trouble.
I'm a young driver who just got my license and don't drive much for work. Last time in the parking lot, my car wouldn't start until a friend reminded me. Turns out you can charge the battery even when the engine is idling, as the alternator feeds current back into the battery when the engine is running. I tried it once and it actually worked. However, I had to sit there for almost an hour just to get the charge level up halfway—it was too slow and wasted fuel. Later, I learned not to rely on this method too much, as a severely depleted battery might not charge at all. A more convenient solution is to keep a portable jump starter in the garage for emergencies, or occasionally take a short drive after work to rev up the engine and activate the battery.
In recent years, I haven't used my private car much and often encountered difficulties starting it in winter. From experience, it's true that keeping the vehicle idling after startup can charge the battery, as the alternator continues working to supply power to it. However, this method charges relatively slowly—with low engine RPM resulting in small charging current, far less efficient than normal driving. Moreover, prolonged idling is environmentally unfriendly, producing more exhaust emissions and wasting fuel costs. I suggest using this method only for short-term emergencies, not exceeding twenty minutes. Additionally, regularly check the battery terminals for corrosion; keeping them clean can extend battery life and prevent charging issues.
