How Preemptive Mode Works
Preemptive mode minimizes screen defrosting time but slightly reduces cold
storage battery life since the heaters enter a low power pre-heat stage before the
computer detects a rise in the ambient temperature.
The heater only enters the low power pre-heat stage once the following conditions
are met in the order listed:
1. The computer detects the ambient temperature has lowered below the set
2. The Heater enabled delay timer expires. A snowflake
3. The Pre-heat enabled delay timer expires.
Note: Once the computer enters the pre-heat stage, the icon changes from a
Pre-heating keeps the windows warm to minimize condensation and frost when
the computer is removed from cold storage allowing for quicker defrost times. The
heaters switch to full power to defrost the windows when the computer detects a
quick rise in the ambient temperature.
In Preemptive mode, the cold storage battery life ranges from a maximum of
6 hours to a minimum of 1.5 hours depending on the Pre-heat enabled delay time
set. The window defrost times range from zero to a maximum of one minute with
factory default settings.
You can configure the heater operation for your individual environment in
Enterprise Settings or by editing the computer registry values. To learn more, see
Configure the Heater
How to Manually Turn the Heaters On/Off
If you want to manually turn the heaters on or off while in cold storage, tap the
If the In freezer heater activation setting is enabled (Preemptive mode), the
Pre-heat enabled delay timer is not stopped if the icons are used to turn the heater
on or off. The timer continues to run and the heaters still turn on when the timer
If the In freezer heater activation setting is disabled, the Pre-heat enabled delay
timer is not used and pre-heating does not automatically start, but the snowflake
75 Series Mobile Computer User Guide
Heater enable temperature.
to a heater
or heater icon
can still be tapped to turn on the heaters for pre-heating.
in the status bar.
icon appears in the