How long can a car battery last after disconnecting the negative terminal?

[OKimberly]

After disconnecting the negative terminal of a car battery, it can last for about 60 days. Below are specific details about car batteries: Introduction: A car battery, also known as a storage battery, is a type of battery that converts chemical energy into electrical energy. Typically, the term "car battery" refers to a lead-acid battery, which mainly uses lead and its oxides as electrodes and a sulfuric acid solution as the electrolyte. Classification: Ordinary batteries, dry-charged batteries, and maintenance-free batteries. Principle: It uses a lead plate filled with sponge lead as the negative electrode, a lead plate filled with lead dioxide as the positive electrode, and a 22-28% dilute sulfuric acid solution as the electrolyte. During charging, electrical energy is converted into chemical energy, and during discharging, chemical energy is converted back into electrical energy.

[BrynleeMarie]

I think this is a pretty common issue, especially since many people leave their cars unused these days. If you disconnect the negative terminal of the car battery, it can prevent unnecessary power drain from the electrical system. How long the car can sit depends on the specific conditions. From my own experience, leaving it for two to three weeks is usually fine if the battery is still healthy. But if it exceeds a month, the battery's self-discharge will gradually drain it, and once the voltage drops below 12 volts, it can easily get damaged. Once, I came back from a month-long business trip and had trouble starting the car—I had to quickly charge it to save the battery. I recommend checking the voltage at least once a month, either with a multimeter or by simply starting the engine to recharge. Don’t leave it unused for too long to avoid battery degradation and replacement costs, which can run into hundreds of dollars. For long-term parking, it’s best to use a smart battery maintainer to avoid unnecessary hassle.

[VonIsabelle]

Hey, I've heard from the older generation that disconnecting the negative terminal of the battery can indeed extend storage time. Normally, a car can sit for three to four weeks without much worry. But don't think you can leave it indefinitely—over time, the battery will slowly discharge on its own, especially during summer or winter when temperature fluctuations are greater, causing the charge to drop even faster. I remember one time I left my car in the garage for two months without touching it, and when I came back, the battery was completely dead. I had to replace it, wasting money. So now, if I plan to leave the car unused for a long time, I start it every four weeks to let it recharge. I also clean the terminals to avoid rust. Overall, safety first—don't push your luck.

[DiLuna]

From a technical perspective, disconnecting the negative terminal cuts off the circuit, preventing power drain by vehicle devices. However, batteries have natural discharge, typically at a rate of 2%-5% per month. So how long can a car be safely parked? Generally, three to five weeks is fine, but exceeding six weeks carries risks—voltage may drop below 10 volts, potentially damaging the battery or causing starting difficulties. It's advisable to store the vehicle in a cool place, such as a garage with stable temperatures. After storage, it's best to use a charger to ensure the voltage remains above 12.6 volts. Don't overlook these small details—they can extend battery life and save money.