17 Manual Number 9018047 • Revision L, January 6, 2022
Heating
The TB17 has the ability to be operational at temperatures down to -40°C (-40°F) utilizing
the internal, self-powered heater. The TB17 is designed to support an engine start with no
special considerations down to approximately -5°C (23°F), depending upon the engine start
profile. Below this temperature, the performance of the unit begins to decrease in current
and energy delivery as the electrolyte in the cells begins to thicken and the internal
impedance increases to retard ion flow. In order to address this, each battery module
contains an individual heater which is powered by the cells themselves, even at very low
temperatures. Refer to Table 4.1 for specific conditions governing heater operation.
Heater Operation Condition
-1/-3 Units
-2/-4 Units
Battery is in
Sleep Mode
Heater is disabled Heater is disabled
Battery is in
Active Mode
Heater is enabled
See below
Heater enable pin is grounded (-2/-4 Units
only)
N/A
Heater is enabled
Heater enable pin is open (-2/-4 Units only).
Note: Battery may be in
Sleep Mode
or
Active Mode
N/A
Heater is disabled
Table 4.1
Heater Operation Condition
When the heater is enabled, it is active/on when the temperature of the battery is below
+10°C. The heater will automatically turn off when it r15°C. The unit will continue
to monitor its temperature and turn the heater on again as needed any time the
temperature drops below +10°C and the heater is enabled. This will continue during flight
as needed. Pre-heat time will vary depending on temperature but can be fully warmed in 12
minutes or less after turning the heaters on. Refer to Figure 4.1 for heating time (to +15°C)
based on ambient temperature.
Figure 4.1
Battery Heating Profile
‐40
‐30
‐20
‐10
0
10
20
0
2
4
6
8
10
12
14
Temperature (°C)
Time (Minutes)
TB17 Battery Heating Profile
‐40 C Ambient
‐20 C Ambient
0 C Ambient
Summary of Contents for TB17 Series
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