Current-controlled policies for battery-driven dynamic power management

The availability of multi-battery power supplies adds new degrees of freedom to the problem of increasing the lifetime of a battery system. Proper battery management policies, that decide which battery must be connected to the load, at any point in time, can exploit the additional flexibility offered by the power supply to maximally extend battery lifetime. In this paper, we introduce a novel class of battery management policies based on the fact that the amount of charge a battery can deliver depends on the discharge current drawn from the battery itself. These policies are named current-controlled because the choice of the battery pack to be used at any point in time is driven by the instantaneous current load required by the system. We have explored the applicability of current-controlled policies in the realistic case of a personal digital organizer with various operational modes. Results have shown that battery lifetime extensions over the case of traditional battery discharge are in the range 14-19% for a typical usage profile.