Gen 3 Kits are no longer shipped with a backup battery
With the updates to the hardware components in the Gen3.5 display, there is no longer a need for the backup battery.
In previous display versions, a backup battery was used to ensure that the display operation system, did not reset during engine cranking.
Photo below of the now redundant backup battery
In the latest Gen 3.5 Display, the hardware has been optimised to reduce power requirements and a new power control circuit has been implemented so the display operation system will not reset during engine cranking (even without a backup battery).
However older Gen3 displays will still require a backup battery to be installed and functioning as part of the service process.
The differences between the Gen3 and Gen3.5 displays are shown in the pictures below - of the rear panel of each type:
Rear panel of Gen V3 Display
Rear panel of Gen V3.5 Display