A method and system for swapping batteries in an electric vehicle is disclosed. The method includes dismounting a first battery assembly, moving to a second battery assembly and mounting the second battery assembly onto the vehicle. Mounting and dismounting are accomplished by an onboard mounting and dismounting system. The method can be used in a zero infrastructure environment such as an underground mine since mounting and dismounting are accomplished by components on the vehicle itself. An auxiliary battery pack powers the vehicle during between dismounting a battery pack and mounting another battery pack.