In case anyone stumbles across this with the same problem, this solution seems to work: (the other scheme alias names I have are "HighPerformance" and "PowerSaver")
<Power> <Policy> <Settings> <Battery> <SchemePersonality> <Default SchemeAlias="Balanced"> <Setting> <CriticalAction> <AcValue>3</AcValue> <DcValue>3</DcValue> </CriticalAction> <CriticalBatteryLevel> <AcValue>5</AcValue> <DcValue>5</DcValue> </CriticalBatteryLevel> <LowAction> <AcValue>0</AcValue> <DcValue>0</DcValue> </LowAction> <LowBatteryLevel> <AcValue>10</AcValue> <DcValue>10</DcValue> </LowBatteryLevel> <LowBatteryWarning> <AcValue>0</AcValue> <DcValue>0</DcValue> </LowBatteryWarning> <ReserveBatteryLevel> <AcValue>4</AcValue> <DcValue>4</DcValue> </ReserveBatteryLevel> </Setting> </Default> </SchemePersonality> </Battery> </Settings> </Policy> </Power>