(Thread edited due new information)

Seems pretty obvious, but I have not seen anywhere.

Easy calculations. 4310 mAh bateries, at 3.7 V, (taken from japanese nintendo site) give us 16 Wh. 

Nintendo said 2.5 to 6 hours, this leads to near to 2.7 to 6.4 W.

Also, here: http://www.tweaktown.com/news/55938/switchs-4310mah-battery-takes-3-hours-fully-recharge/index.html specifies dock mode changing wattage. 39W. Suposing It still charges while playing at high-end level, 39W would be the maximum power it sucks.

And what can we expect from these Wattages?

I didn't realise 2.5 hours was the lower end. That's a bit too short for my liking.

Anyway, I would expect it to suck in more juice once docked as I expect the performance to be improved when docked too. The limiting factor at that point would be heat so it would depend on how much extra cooling the dock could provide.

Note: I haven't been following Switch news that closely so I'm only going by what would be logical in my mind.

What about the small batteries in the joycons do they help provide console power in portable mode. Would seem wierd if they just take their power off the main tablet in portable mode so those batteries remain charged when used as a portable and yet when you put the tablet on the table with the little stand they will need to be charged for wireless operation then.

Docked mode definitely can take much more current. 8.6w is 1.72A at 5V and its only the gpu that will need more power plus perhaps some additional power for usb output etc. I guess 3A output would cover it plus allow some charging current too or 3.5-5A would allow more rapid charging plus docked performance.

I expect ~3.8 V in such a form factor.

Nvidia Shield tablet K1 has 3.8 V (5100 mAh, 19.38 Wh), iPad Mini 4 has 3.82 V (5124 mAh, 19.32 Wh), PSVita has 3.7 V.

So I expect 3.8 x 4310 mAh = 16.4 Wh, this leads to 2.7 - 6.5 W in portable mode and probably around 20 W in docked mode.

Probably atleast 4 times that 8.5watt range.

I wouldnt be surprised if its like 35+ watts range when docked.

Its less than the 80watts or so a PS4 slim uses.

But then again its like 1/3rd the performance, so it makes sense it uses less power.

Zelda is just abit under 3hours supposedly.

So the its only the most demanding games that ll have 2.5hours. Most will probably be around 3.

The more important information of the added specs for me is the weight of the device.

I was worried about a brick like the Shield handheld (579 g), but the 398 g of the Switch (with Joy-Cons attached) is okay for me.

My 3DS XL ain't much lighter. I made a comparison of the dimensions and weight of different handhelds/tablets and game controlelrs:

According to teaktown is a 3.7v one. They cite Ninty japan site as their source. Here is their very in deph analisis: http://www.tweaktown.com/news/55938/switchs-4310mah-battery-takes-3-hours-fully-recharge/index.html

Further Analisis:
http://www.tweaktown.com/news/55965/nintendo-switch-battery-life-analysis/index.html

That's some good info plus i'd forgotten about lithium ion battery packs having 3.6-3.8V output.

0.4kg seems too heavy to me. I have a 3DS XL but tend to use that home and use a standard 3DS for travelling. It's not ridiculous in weight but its not the compact light weight design that Nintendo have been famous for. 

I certainly feel Switch needs to get lighter and smaller in the future but maybe I'm wrong perhaps that weight will be accepted.

Thanks!

Thread edit.

Wow, nice informations.

So, joy-con at 50g each seems pretty light. The lightest (100g)way to play in history with full button configuration(2 analog sticks, 4 shoulder buttons and face buttons). Also, joy-con grip is kinda heavy... 98g for a piece of plastic that conect 2 joy-con.. :(

If is confortable enough, I choose my configuration! Joycons only when on TV, and tabletop while on-the-go. =)