A computing device comprising: a battery system having multiple batteries; a power management system configured to: associate a discharge parameter with a particular battery of the multiple batteries, the discharge parameter configured to cause servicing of a system load for the computing device by: first discharging the particular battery down to a charge level specified by the discharge parameter; and then switching among using one or more of the multiple batteries at a time to service the load; expose functionality operable to enable adjustment of the discharge parameter to specify different charge levels and thereby selectively control a tradeoff between device performance and reliability of the multiple batteries for different usage scenarios; adjust the discharge parameter to adapt to a current usage scenario, responsive to a directive received via the functionality; service the system load for the current usage scenario in accordance with the discharge parameter as adjusted; and the power management system including a power manager module implemented as a component of an operating system for the computing device and a power controller including distribution circuitry operable under the influence of the power manager module to selectively charge and discharge the multiple batteries, the power manager module configured to adjust the discharge parameter automatically based on an assessment of a combination of cycle counts of the multiple batteries and power requirements to support the current usage scenario for balancing the device performance and reliability of the multiple batteries. a battery system having multiple batteries; a power management system configured to: associate a discharge parameter with a particular battery of the multiple batteries, the discharge parameter configured to cause servicing of a system load for the computing device by: first discharging the particular battery down to a charge level specified by the discharge parameter; and then switching among using one or more of the multiple batteries at a time to service the load; expose functionality operable to enable adjustment of the discharge parameter to specify different charge levels and thereby selectively control a tradeoff between device performance and reliability of the multiple batteries for different usage scenarios; adjust the discharge parameter to adapt to a current usage scenario, responsive to a directive received via the functionality; service the system load for the current usage scenario in accordance with the discharge parameter as adjusted; and the power management system including a power manager module implemented as a component of an operating system for the computing device and a power controller including distribution circuitry operable under the influence of the power manager module to selectively charge and discharge the multiple batteries, the power manager module configured to adjust the discharge parameter automatically based on an assessment of a combination of cycle counts of the multiple batteries and power requirements to support the current usage scenario for balancing the device performance and reliability of the multiple batteries. associate a discharge parameter with a particular battery of the multiple batteries, the discharge parameter configured to cause servicing of a system load for the computing device by: first discharging the particular battery down to a charge level specified by the discharge parameter; and then switching among using one or more of the multiple batteries at a time to service the load; first discharging the particular battery down to a charge level specified by the discharge parameter; and then switching among using one or more of the multiple batteries at a time to service the load; expose functionality operable to enable adjustment of the discharge parameter to specify different charge levels and thereby selectively control a tradeoff between device performance and reliability of the multiple batteries for different usage scenarios; adjust the discharge parameter to adapt to a current usage scenario, responsive to a directive received via the functionality; service the system load for the current usage scenario in accordance with the discharge parameter as adjusted; and the power management system including a power manager module implemented as a component of an operating system for the computing device and a power controller including distribution circuitry operable under the influence of the power manager module to selectively charge and discharge the multiple batteries, the power manager module configured to adjust the discharge parameter automatically based on an assessment of a combination of cycle counts of the multiple batteries and power requirements to support the current usage scenario for balancing the device performance and reliability of the multiple batteries.