Safely disconnect and remove a car battery by taking off the negative terminal first.
Switch off the ignition, remove the key, and let the engine cool. Wear safety glasses and gloves — battery acid is corrosive and terminals can spark.
Loosen the nut on the negative (-) clamp, usually black, with a wrench and lift the cable off. Removing the ground first prevents your wrench from causing a short if it touches metal.
Loosen and remove the positive (+) clamp, usually red. Tuck both cables aside so they can't fall back onto the terminals while you work.
Unbolt the clamp or bar that secures the battery in its tray. Keep the bolts together so you don't lose them before reinstalling.
Grab it by the carry handle or both ends and lift evenly — a typical battery weighs 30 to 50 pounds. Keep it upright to avoid acid spills and set it on a stable surface.