How thick should the cables be for jump-starting a car battery?
2 Answers
For jump-starting a car battery, generally 2.0*2.5 pure copper national standard cables are sufficient, and 16 square millimeter copper cables will work. The current during startup is very large, while the normal operating current is several tens of amperes. Additional information: 1. Requirements for charging cables: The thickness of the cables has model requirements, usually calculated in square millimeters, and is generally indicated on the car's circuit diagram. The battery connection cables must handle the starting or charging current. Depending on the starter's power, cables of 25 square millimeters or more are generally required, while charging cables are typically 6 square millimeters. The battery cables consist of two separate wires, and the charging connection cables are integrated into the wiring assembly. 2. Precautions: When purchasing cables, not only the thickness but also the length matters. If the jump-start cables are too long, they can easily lose power, making it impossible to start the vehicle. It is generally recommended to use jump-start cables that are 3-4 meters long. Additionally, avoid purchasing cables that cost only a few dollars, as their quality is very unreliable. They are not only prone to leakage but may also damage the car.
I've been driving for over a decade and have experienced several jump-start situations. The key is to use jumper cables thick enough—at least 4 or 6 gauge, with a cross-section of around 10 square millimeters. This ensures they can handle the hundreds of amps needed for engine cranking. Thin cables heat up rapidly under high current, potentially melting the insulation and causing a fire, which is no joke. Especially in winter when battery voltage drops, the demand increases. Keep the length short, ideally under 1.5 meters; if longer cables are necessary, like for cross-vehicle rescues, upgrade to thicker 2-gauge cables to compensate for voltage drop. I prefer branded jumper cable sets with clear specifications on the packaging—reliable and hassle-free. Regularly inspect cables for damage or corrosion to prevent issues. Safety always comes first—never cut corners with household wires. Once, I nearly damaged a friend's car doing that.
