Which Battery Terminal Must Be Disconnected First And Why?

Which battery terminal should be disconnected first?

When removing the old battery, remember to first disconnect the cables from the negative terminal, which is usually black and has a minus (-) sign then disconnect the cables from the positive terminal, which is usually red and has a plus (+) sign..

Why do you connect the positive terminal first?

Connect positive first, negative having less potential won’t arc. The higher the voltage, the greater the chance of arcing and fusion. On a car if negative first and you are touching any metal part of car, when attaching positive there is possibility of arcing through you. Your body becomes part of the circuit.

Why do you disconnect the negative terminal first?

By removing the negative battery cable you are disconnecting the battery from the chassis of your vehicle. If you begin to remove the positive side before the negative and your wrench would make contact with any part of the vehicle, then you could cause a short in the system.

When a battery is disconnected the earth lead should always be disconnected first because?

Because the negative end of the battery is connected to ground. It is only a slight advantage to disconnecting the positive terminal. The reason for this is because while connected, any part of the chassis will complete the circuit and the chassis is one big wire that is easy to bump into.

What happens if you connect the negative terminal first?

The negative cable is connected to the body/chassis of the car. … If you connect the negative first, then the positive, if you happen to touch the wrench to something metal while it is touching the positive terminal, that’s a short – because the chassis is already connected to the negative battery terminal.

Do I have to disconnect both battery terminals?

No, it won’t. You can disconnect whichever terminal you want, or even both, it won’t discharge. Whichever one you choose results in an open circuit so no current can possibly flow.