The battery loses its charge
It might come as a surprise, but your car is still working even when you're not driving it. "Just like your laptop or cell phone, your car battery is running the computer inside your vehicle at all times," says Joe Akers, director of operations at Cowless Nissan in Woodbridge, Virginia. If you're not going to be driving your car for a few weeks, Akers recommends placing your vehicle on a trickle charger. "These chargers continue to supply power to a car battery when the vehicle is not in use," Akers says. Oh, and don't forget to remove the phone charger, dash-cam, and any other power-consuming devices plugged into the cigarette lighter port. "These devices slowly seep your juice, too," notes Jesse Yuvali owner of Jesses' Garage European Auto Repair in Sarasota, Florida. While you're at it, never leave these things in your car.
9 Things That Can Happen To Your Car When You Don't Drive It, Source:https://www.rd.com/advice/things-that-happen-to-your-car-when-you-dont-drive/
