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When connecting your battery, connect the positive (red) first and the negative (black) second. When removing the battery, disconnect the negative (black) first and the positive (red) second. Been doing this for nearly 30 years. ALWAYS connect the positive post first.
If you connect the negative first you have made a connection from  the battery to the whole body of the vehicle. When you then connect  the positive using a spanner (wrench)â¦ and whilst(while) touching  the positive terminal connect with the body of the vehicle with the  other end you will cause a short circuit.