The Joy-cons have their own battery though, so they shouldn't draw any power from the main unit battery, unless the tests were done with depleted Joy-con batteries.
I even read somewhere (maybe Reddit?) that once the main console runs low on battery, the console starts sipping power from the Joy-con batteries, if they have enough charge left. As the Joy-cons supposedly last ~20 hours, that should be the norm if both are fully charged, therefore further increasing the available power for the main console from 16 Wh to ~19 Wh.
In general I would be really interested in trying to calculate the power consumption for all of the parts based on the Zelda runtime, so we can have a better guess on the actual hardware and clockrates of the SoC.
For the Display, the closest one with power measurements i could find is the Mate 8 Display
http://www.anandtech.com/show/9878/the-huawei-mate-8-review/6
Only 6" instead of 6,2", but also 1080p instead of 720p, so power consumption should be fairly close. I haven't seen a switch in person yet, but from reading a lot of first impressions, i would guess that the switch is brighter than the 3DS and Wii U Display, but doesn't come close to modern smartphones. So somewhere between 200 and 300 nits sounds reasonable, which would correlate to between 0.8 and 1 watt.
(For comparison, the 3DS got around 150 nits, while the new 3DS managed 161 nits according to
https://www.welt.de/wirtschaft/webw...eue-Nintendo-3DS-hat-den-Zocker-im-Blick.html)
The SoC calculations were already done before in this thread (assuming 4 Cores), iirc that resulted in:
~2,5 watt: Eurogamer clocks, A57 @20nm (1,83 + ~0,7)
~1,5 watt: Eurogamer clocks. A57 @16nm (1,16 + ~0,4)
~6,5 watt: Foxconn clocks, A57 @20nm (5,46 + ~1)
~4,3 watt: Foxconn clocks, A72 @20nm (~3,3 + ~1)
~4,2 watt: Foxconn clocks, A57 @16nm (3,65 + ~0,6
~2,8 watt: Foxconn clocks, A72 @16nm (2,2 + ~0,6)
All the values with a ~ are estimations, mostly based on
http://www.anandtech.com/show/8811/nvidia-tegra-x1-preview/3
The other values come from:
http://www.anandtech.com/show/9330/exynos-7420-deep-dive/5
http://www.anandtech.com/show/8718/the-samsung-galaxy-note-4-exynos-review/6
http://www.anandtech.com/show/9878/the-huawei-mate-8-review/3
I think those numbers might be accurate up to +- 20% of the actual value
Wlan shouldnt be active while playing Zelda, or atleast power draw should be negligible
Joy-cons have their own battery.
Do we have any information about the Speakers?
No idea about the Ram, that might be one of the bigger power consumers while playing.
Nand and microsd should also be negligible.
Did i forget anything?