Every 3-6 months, aerospace batteries must be removed from the aircraft, the electrolyte dumped out and fresh electrolyte added, and the batteries charge-cycled to remove the NiCd “memory effect.” Under a supplemental-type certificate (STC), Æsir is planning to introduce a battery for the Cessna Citation series first and then for the Boeing 737. The Citation has approximately 8,500 deliveries to date, and the 737 has over 7,000.