The Li-Ion Battery Pack (pictured below) is designed to be used with 2 fully charged C-cell batteries to power a model 2000, 4000, 6000 or PainSmart™ infusion pump for an extended period of time without being connected to a power outlet. The battery pack allows the user to operate the pump for a minimum of 24 hours (at 125mL/hr) in addition to the run-time supplied by the disposable C-cells in the pump. To ensure an adequate low battery warning period, the battery pack should always be used with 2 fully charged C-cell batteries installed in the pump.