How Long Can a Car Battery Last Without Use?

[DeIvan]

An unused car battery can last for about two months. When storing a car for an extended period without use, it is advisable to disconnect the positive and negative terminals of the battery to prevent natural power drain from onboard electronics. If the battery loses charge, driving normally for one to two hours can restore its power. However, if the battery is too depleted to start the engine, a jump-start may be required to reactivate it. A car battery is a device that converts chemical energy into electrical energy, functioning as a DC power source. Its main purposes include: 1. Providing a strong starting current to the starter motor during engine ignition; 2. Assisting the alternator in powering electrical devices when it is overloaded; 3. Supplying power to electrical devices when the engine is idling.

[MacAurora]

My old car wouldn't start after sitting idle for less than three weeks. The mechanic later explained that car batteries gradually discharge when unused. A new battery can typically last about a month, but an older battery that's been in use for two or three years may drain within roughly two weeks. This discharge accelerates in winter when temperatures drop below freezing – last year during the Spring Festival holiday, I faced the embarrassing situation of being unable to start my car after just fifteen days away. The safest approach is: if you won't be driving for over two weeks, either have someone start the car for about ten minutes weekly to recharge, or simply disconnect the negative battery terminal. This way, even leaving it for two or three months won't be a problem. Just remember to turn off all electrical devices before disconnecting the battery, otherwise the anti-theft system might trigger an alarm.

[AmaraAnn]

I alternate between driving my two cars, and one of them often sits idle for more than half a month at a time. Based on actual tests, batteries with start-stop functionality tend to last longer—they can hold a charge for up to a month without dying, while regular batteries usually max out at around 20 days. Once, I had a dashcam with 24-hour parking surveillance running in the car, and it drained the battery completely in just five days. Now I’ve learned my lesson: before long-term parking, I make sure to check if power-hungry devices like the GPS and anti-theft system are completely turned off. Battery lifespan also plays a big role—by the fourth year of owning this car, it needed a jump-start after just a week of sitting idle. I recommend car owners use a voltmeter to check the battery before long-term parking; a reading above 12.4 volts is considered safe.