Peak Shift is an optional feature that reduces power consumption by automatically switching the system to battery power during certain times of the day, even if the system is plugged into a direct power source. Peak Shift feature is a utilitarian feature for the power conscious who want to streamline power consumption from mainlines. Essentially Peak Shift feature is presented to the user in BIOS F2 screen as shown below:
The user can enter values for peak shift start, peak shift end and peak shift charge start. These values are for each day of the week. These values are basically time fields in 12- hour time format. The user can also specify AM/PM. Then the user can enter battery threshold ranging from 15% to 100%. Finally the user can either Enable or Disable peak shift for the weekdays with an ‘Enable Peak Shift’ check box. The import of the salient above fields is explained below.
When peak shift is enabled, the following takes place using the user set daily times and threshold value:
- From “Peak Shift Start” until “Peak Shift End”, AC power is not used unless “Battery Threshold” is reached. Even is the system is connected to AC power, the machine only uses battery power until threshold is reached. Also during this period quite naturally battery does not charge. When battery threshold is reached the system switches to AC power but does not charge battery.
- From “Peak Shift End” until “Peak Shift Charge Start”, AC power is used when available but the battery does not charge.
- Apart from the span between “Peak Shift Start” and “Peak Shift Charge Start”, AC power is used when available and battery is also able to charge.
The validation that goes into place when enter peak shift times is that Peak Shift Start<=Peak Shift End<=Peak Shift Charge Start. In other words Peak Shift Start time must be less than or equal to Peak Shift End time and Peak Shift End time must be less than or equal to Peak Shift Charge start time. Otherwise BIOS F2 and DCPP complains to user to adhere to this validation.
Dell Command Powershell Provider(DCPP) has strived hard to present to the user Peak Shift feature as closely adhereing to BIOS F2 screen as possible. DCPP provides the below 3 attributes for facilitating Peak Shift feature:
As seen in the above screen shot DCPP facilitates Peak Shift through 3 attributes viz Peakshift, PeakShiftBatteryThreshold and PeakShiftDayConfiguration. ‘PeakShift’ is a simple attribute that takes only values ‘Enabled’ and ‘Disabled’. ‘PeakShiftBatteryThreshold’ is an integer attribute that accepts values between 15 and 100(similar to F2). The generic usage of the above attributes is shown in the screen below:
‘PeakShiftDayConfiguration’ is a more custom token which needs more discussion on its usage. Similar to table in which F2 screen provides for changing data related to independent weekdays, PeakShiftDayConfiguration allows the user to get and set day-wise information. To view current day wise settings for Peak Shift the below command must be used and also depicted is a screen shot:
Dir PeakShiftDayConfiguration|Select –ExpandProperty CurrentValue
As seen in the above screen shot, the user can avail Peak Shift info quite similar to F2 screen. The table is listed as Day of week, its StartTime, its EndTime and ChargeStartTime. All these fields have same import as in F2 screen. To set Peak Shift data for a day of week, we have to run the below command and below is depicted a screen shot also:
Set-item PeakShiftDayConfiguration Tuesday –StartTime “11:30” –EndTime “12:30” –ChargeStartTime “14:30”
As seen above, the user has changed Peak Shift data for ‘Tuesday’ with the shared command. Similar to F2 the validation exists viz StartTime<=EndTime<=ChargeStartTime
NOTE: If either system or admin password is set, then during set operations password must be provided with a –Password switch. Example below:
Set-item PeakShiftDayConfiguration Tuesday –StartTime “11:30” –EndTime “12:30” –ChargeStartTime “14:30” –Password myAdminPassword