See airframe manufacturer's maintenance manuals or STC for instructions specific to a particular aircraft model. Desconnect any external power supply. Open battery compartment access panels. Disconnect battery quick disconnect plug or remove terminal bolts and disconnect battery cables from battery terminals. Always disconnect the ground cable first and install the ground cable last Disconnect battery ventilation tubes, if any.
Unlock battery hold down clamps and remove.
Carefully remove battery. Batteries are heavy. Use appropriate lifting devices or equipment. Use battery handles where provided. Desconnect any external power supply.