Car Battery Remove Negative Or Positive First. 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. If you remove the negative clamp and inadvertently complete a circuit to ground there will be no current flow.

DISCONNECTING YOUR BATTERY. When disconnecting the cables from the old battery disconnect the negative first then the positive. You should always remove the NEGATIVE terminal cable first.
Do you remove the positive or negative first on a car battery.
The one with the nipple is the positive sign and the flat side is the negative. The exact installation method will vary depending on whether you are installing a top-post or side-post battery. The nut on the negative terminal of your battery can be held against if you grab a sockets from your kit. Second always remove the batterys ground clamp before loosening the positive.

