When a car is not used for a long time, should the positive or negative terminal of the battery be disconnected?

[DeNaomi]

When a car is not used for a long time, the negative terminal of the battery should be disconnected. Disconnecting the negative terminal cuts off most of the standby power consumption in the vehicle, allowing the battery to discharge naturally. Removing the negative terminal can help the car stay parked for a longer period and better protect the battery. The reason for disconnecting the negative terminal first is that the negative terminal of the car battery is connected to the car body, which is made of metal, meaning the entire body is connected to the negative terminal. If the positive terminal is disconnected first, it may easily lead to electrical conduction. Generally speaking, disconnecting the negative terminal of the car battery will not cause any problems for one to two months. However, long-term parking can still affect the car battery and other components. For example, prolonged parking can cause tire deformation leading to premature tire failure, oxidation and deterioration of engine oil, and paint peeling.

[McDaniella]

Disconnecting the negative battery terminal is the proper procedure. Even when a vehicle is left idle for extended periods, the battery will still gradually discharge. Removing the negative terminal completely cuts off the power drain from onboard electronics. If you disconnect the positive terminal instead and accidentally touch the wrench to the vehicle's metal body, it could cause a dangerous short circuit with sparks flying. Our workshop foreman always says 'disconnect negative, never positive' - since the vehicle frame itself is connected to the negative terminal, removing it effectively shuts off the entire electrical system. As a side note, if you're planning to store the vehicle for 3-4 months, it's advisable to recharge the battery every two months. Otherwise, you might return to find you need a brand new battery, which would be counterproductive.

[JourneyLynn]

I'd say disconnecting the negative terminal is the easiest solution. Just last week, I handled my neighbor's SUV that had been parked for six months - removing the negative battery terminal completely cuts power to the system. When disconnecting the positive terminal, you need to be extra careful not to let tools touch the chassis, as all metal parts of the frame are connected to the negative terminal - a single slip could cause sparks to fly. Actually, after disconnecting the cable, it's best to wrap the negative terminal with insulating tape to prevent accidental grounding and current leakage. Also, remember to unplug power-draining gadgets like dashcams during long-term parking - I've seen cases where people forgot to unplug their dashcams and completely drained the battery in just two months.

[NolanAnn]

Let me give you the conclusion directly: prioritize disconnecting the negative terminal. Last year, my old Jetta was left unused for four months while I was abroad, and the mechanic taught me this trick. The principle is simple—the entire metal frame of the car serves as the negative circuit, and disconnecting the positive terminal offers less working space and risks sparking. To disconnect the negative terminal, just insert a wrench into the clamp screw and turn it counterclockwise twice to loosen it—the whole process takes just ten seconds. One important note: don’t lock the car before disconnecting, and leave a small gap in the driver’s window for ventilation. I learned this the hard way—after disconnecting, the central locking system engaged, and I had to climb in through the trunk to fix it later.

[RebeccaFitz]

Actually, disconnecting the negative terminal is equivalent to cutting off the main power switch for the entire vehicle. Remember the current circuit from middle school physics? The car's steel frame acts like the negative wire—disconnecting the negative terminal completely breaks the circuit. Removing the positive terminal is not only dangerous but also risks short circuits if it touches other metal parts. Last time I helped my cousin with his idle car, I found his car charger was still plugged into a power bank. Small devices like this can still drain power if left connected, so it's advisable to check the cigarette lighter and USB ports before disconnecting. For long-term parking, it's best to start the engine for about twenty minutes each month to recharge the battery.