A:AnswerThanks for your inquiry Jack. The replacement battery of BN1050M is APCRBC158. You may also refer to page 16 of the user guide for confirmation: https://download.schneider-electric.com/files?p_Doc_Ref=SPD_BU-UM-TME13690_EN&p_enDocType=User+guide&p_File_Name=BU_UM_TME13690_EN.pdf