Customers are affected by power outages due to supply shortage, maintenance and other unexpected events. Utilities are evaluated by the authorities on metrics such as SAIDI and SAIFI that are based on the outages' duration and frequency. During outages, islanding is often used to supply backup power to a subset of the load by using local energy sources such as batteries or micro-generation. Due to the limited capacity of secondary supply, Adaptive Dynamic Islanding is used to dynamically allocate the energy among the customers during outages. Battery characteristics such as lifetime and available capacity depend on the usage patterns. Therefore, when battery is used as the secondary source for islanding, it is important to schedule the supply to satisfy the customer demand and improve reliability metrics while taking into account battery capacity and energy costs. Towards this, we propose a method for optimally scheduling supply from a shared battery among a set of customers during Adaptive Dynamic Islanding. Additionally, we also present a pricing mechanism to bill the customers for their consumption during islanding based on their usage patterns. This helps in avoiding penalizing customers for the usage behaviour of others in the community using the same shared battery. We show experimental results based on real consumption data and battery specifications.