Tablets

Technician of 5 years here. This really does have me stumped so any further advice would be appreciated. I have 3x iPADS = 2X iPAD 5, AIR 2 here. All are draining more than 30% overnight on standby. Latest iOS installed at the time of writing this (12.1). Freshly flashed so no apps installed or running in the background when these multiple
"overnight drain tests" where completed. Charged to 100% before each test.

Lets start with the AIR 2 (3G)
Manufacture date = 2014
Battery percentage capacity reading = 99%
cycle count = 184
Tristar/Hydra = pass. PP5V0_USB (Tigris) is not shorted to ground.
Dock test = pass. Diode mode measurement to check the Dock Flex assembly for proper connection to the MLB. Rail 1-3 and 5-7 are connected to Tristar/Hydra. Changed to a new battery. Tested drain overnight again. Issue is still present.
All the same test were completed on the following pads. All yielded similar results.

iPAD 5 Manufacture date = 2017
Battery percentage capacity reading = 98%
cycle count = 114
Tristar/Hydra = pass. PP5V0_USB (Tigris) is not shorted to ground.
Dock test = pass. Diode mode measurement to check the Dock Flex assembly for proper connection to the MLB. Rail 1-3 and 5-7 are connected to Tristar/Hydra. Changed to a new battery. Tested drain overnight again. Issue is still present.

iPAD 5 Manufacture date = 2017
Battery percentage capacity reading = 100%
cycle count = 9
Tristar/Hydra = pass. PP5V0_USB (Tigris) is not shorted to ground.
Dock test = pass. Diode mode measurement to check the Dock Flex assembly for proper connection to the MLB. Rail 1-3 and 5-7 are connected to Tristar/Hydra. Changed to a new battery. Tested drain overnight again. Issue is still present.

Has left me scratching my head.…..