which is negative and positive on a car battery

[LeAngela]

The positive terminal on a car battery is marked with a plus sign (+) and is typically covered by a red cap. The negative terminal is marked with a minus sign (-) and has a black cap. Connecting jumper cables or a charger to the correct terminals is critical for both safety and proper vehicle operation. The positive terminal is the power source connected to the vehicle's electrical system, while the negative terminal is the ground connection, completing the circuit.

Mixing up the terminals can cause severe damage. Reverse polarity—connecting positive to negative—can fry your car's electronic control unit (ECU), fuse box, and other sensitive electronics, leading to extremely expensive repairs. It can also cause the battery to overheat, potentially resulting in a rupture or explosion.

When jump-starting a car, always follow the correct sequence: connect the positive (+) clamp to the dead battery's positive terminal, then connect the other positive clamp to the booster battery's positive terminal. Next, connect the negative (-) clamp to the booster battery's negative terminal. Finally, attach the last negative clamp to an unpainted metal surface on the dead car's engine block, not the negative terminal of the dead battery. This final connection away from the battery minimizes the risk of sparking near battery gases.

For quick reference, here are the key differences:

Feature	Positive Terminal (+)	Negative Terminal (-)
Color Code	Red	Black
Symbol	Plus Sign (+)	Minus Sign (-)
Function	Power Output (to car systems)	Ground Connection
Connection Point for Jumper Cables	First clamp connected, on both batteries	Last clamp connected; to engine block on dead car
Risk of Incorrect Connection	Short circuits, severe electrical damage	Completes a dangerous reverse-polarity circuit

Always double-check the symbols and colors before making any connections. If you're ever unsure, it's best to consult your owner's manual or call for professional assistance.

[StLillian]

I learned this the hard way. Positive is red, negative is black. The big deal is that if you hook up jumper cables backwards, you can zap your car's computer. That’s a repair bill you really don't want. My rule is red to red first, then black to a clean metal part on the engine of the dead car. Just keep the black clamp away from the dead battery itself to avoid sparks. It’s a simple check that saves a ton of trouble.

[Lilian]

It's all about safety. The positive side is the source, and it's clearly marked with a '+' and is almost always red. The negative side is the ground. The key is to always connect and disconnect the negative cable last when working on the battery. This prevents your wrench from accidentally short-circuiting between the positive terminal and any grounded metal, which would cause a huge, dangerous spark. Color and symbols are your best friends here.