The reason they say to remove the negative first is because it is safer for you. The negative cable in all modern cars is attached to the chassis of the car. SO when you put your wrench on the negative post to loosen it, and the wrench hits the chassis, nothing happens.
Why do you disconnect the positive terminal first?
The reason for disconnecting the -ve terminal first is because it disconnects the whole bike ( or automobile ) frame from the battery: it's a safer. Consider case A: Disconnect -ve terminal first. You are using a wrench ( spanner if you are British ) to undo the bolts on the battery terminal…
Can I disconnect the positive terminal first?
When disconnecting the cables from the old battery, disconnect the negative first, then the positive. Connect the new battery in the reverse order, positive then negative.” When you are replacing your car battery, It isn't always easy to remember the order in which to disconnect and reconnect the terminals.
What happens if you disconnect the positive terminal of the battery?
If you're disconnecting the positive terminal first, and the spanner touches any part of body or engine, you'll get a massive spark and potentially damage your battery also. By disconnecting the negative first, you eliminate the risk of *grounding” your battery on the car body or engine.
What happens if you disconnect the positive terminal first?
If positive terminal is removed first then chances of a spark are more if this terminal touches the body through the metal spanner or wrench you are opening with is grounded accidentally and may end in flames because lot of combustible material is around. And chances of this accidental touch are very high.
What happens if you connect the negative terminal first?
It is only a safety issue. If you first connect the negative cable, then when you connect the positive cable there is a chance the wrench will complete a circuit between the battery and the chassis of the car. This will at a minimum generate a spark, but that spark could eject molten metal toward you causing injury.
What does disconnecting negative terminal do?
Hence by disconnecting the negative side of the battery, It electrically isolate every electrical component from any kind of accidental short circuits, making it much safer especially if there is any fuel leaks or gas fumes..