Notion Ink

How to discharge your Adam with-in 6 hours?

Posted in Uncategorized by Rohan Shravan on October 29, 2010

Dear All,

I wrote in the last post that you can easily get 15 hours from the device. My personal use case is different and so will be yours. Blogs world over picked up this line as posted as Adam gives 15 hours. I don’t think that’s the right way to look at it.

You might have noticed that your phone might work for 2 full days and might require 2 charges a day. Based on the use cases devices claiming 10 hours have ended in 4 hours (3D gaming). Clearing this confusion is extremely important, so here we are with the post “How to discharge your Adam in 6 hours only?” Here is the list which we have compiled:

  • Play 1080P¬†continuously¬†with full brightness and at full volume (displayed as 1024 on Adam and not via HDMI to TV) (no idle time) (Adam has BIG speakers)
  • Play YouTube Flash videos on Wi-Fi or 3G network (no idle time)
  • Use Streaming 3D maps on 3G network with GPS
  • Record HD Video and stream it over the Wi-fi networks
  • Play an augmented reality 3D game with camera input over the network (wi-fi of 3G)

There can be so many use cases where you can discharge it much faster than your normal use case, so be cautious when you read “Adam claims minimum 15 hours of battery”! There tests are on full display, full volume which is never going to be true. Pixel Qi display is 10 times efficient so a huge drop here, if you use earphones, you get more juice and so on..

Will be posting that interactive chart so we all would know our own usage times.

Warm Regards

267 Responses

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  1. josh said, on October 29, 2010 at 12:37

    hopefully alot outside wih backlight off, I plan to use this outside mostly and use my netbook inside.

    • mobz said, on October 29, 2010 at 12:40

      Rohan, do you’ve any idea how long can the adam last just using the pixel Q screen for reading a pdf with everything else off? perhaps other than wifi?


    • hasibanin said, on October 29, 2010 at 15:42

      guess it’s so long that the test is not finished yet!

    • Mufeed said, on October 29, 2010 at 16:03

      I am wondering about that too. My main usage for adam will be for reading.

    • Pingu said, on October 29, 2010 at 16:44

      Does this tablet have the same ebook reading functionality of the OLPC with a Pixel Qi screen? Apparently if it’s displaying a static image the computer can go to sleep while the monitor is still displaying the still image.

      Search for “swizzling”. It seems technically unrelated to the Pixel Qi screen, it’s more about the display controller chip, but it seems like a great idea anyway since without the backlight the power draw would be much lower and perhaps make this power saving worthwile where it wouldn’t be with a normal screen.

    • Thomas said, on October 29, 2010 at 20:15

      The screen uses around 0.5 watts (that is about 5x more efficient than normal lcd, not sure where Rohan is getting his info, I’m getting it from pixel qi website) when backlight is completely off. I’d guess the rest of the system can run for less than 0.2 watt if you’re really not doing much else. That’d give around 24 whr/0.7watt = 35 hours. Maybe even more.

      I really think Rohan should make that calculator, people are going to get confused by all this. Although I really like the honesty. Gives me hope.

    • Thomas said, on October 29, 2010 at 20:39

      Just a bit of info for people.

      The screen uses power to hold the image and power to light it with LED backlight. In pixel qi you can turn off the led backlight completely, but you still need to refresh the picture, which does cost some power.

      Screen power usage according to pixel qi:
      BL OFF: 0.41 watt (30 fps) or 0.54 watt(60 fps). BL ON: 2.5 watt (total).

      1080p playback takes around 0.5 watt according to nvidia, so full screen brightness plus 1080p playback would be around 3 watts. Now, add speakers at full power to that… I dunno… Rohan says they’re pretty loud… 1 watt? That’s 4 watts total.
      24 whr /4 watt = 6 hours.

      Turn off backlight, then it’s only 2 watts. Use headset and it’s (im guessing here, it’s probably less) 1.5 watt, so: 24/1.5 = 16 hours of playback.

      The thing about pixel qi is that the screen is always using ambiant light, so even if you have the backlight on, you don’t need it as high as you’d normally need with ie. an ipad. So the screen will be using between 0.5 watt and 2.5 watt depending on your setting. Simply talking about ‘battery life using the tablet’ is absurd… It depends, it really, really depends when you have pixel qi.

    • Vladimir Kelman said, on October 29, 2010 at 22:00

      Excellent question! I hope to hear an answer from Rohan. Indeed, reading books in ePub / PDF on Adam’s Pixel Qi screen is one of the main attractions.

  2. peter said, on October 29, 2010 at 12:37

    thats sick
    I wanna see a laptop/tablet run a heavy 3D game on battery mode for 5 hours

    • Arioch said, on October 29, 2010 at 16:00

      that’s relatively simple.
      You just need to carry batteries of some laaaarge truck in your backpack. And some wiring.
      More civilised but less efficient way would be to have some industrial-grade UPS in you backpack, but this would have losses into conversion to AC 220V/110V by US and back back Adam.

      However you can not overrun simple rule that modern chemistry only allows limited xxx W-hr per cm-cube of battery volume. Maybe alcohol fuel cells, whenever they be made mainstream, would change it.

    • James said, on October 29, 2010 at 16:18

      wouldnt bother converting it back up and then back down again. waste of energy

    • Arioch said, on October 29, 2010 at 17:18


      Yes, that is more effective.
      But with all that self-made wiring, they may think of you that you have TNT in your backpack. At least some hysteriac would.

      Though in rural areas that would be more practical. And you’d easier find some lorry or tractor to charge them :-)

    • James said, on October 29, 2010 at 18:53

      Lol, maybe Rohan should think about designing a built in Dynamo! That would solve people coming after you for using there plant to charge your adam!

    • James said, on October 29, 2010 at 18:55


    • josh said, on October 29, 2010 at 23:17

      a ion 2 netbook might be able to do this not sure

  3. matt said, on October 29, 2010 at 12:38

    it lasts somewhat like a netbook then :)

    • sunchicax said, on October 29, 2010 at 23:11

      Hm, dunno if you are being serious (my irony detector sounded, but not too loudly, so it could be a false positive, haha :)), but just to clarify… Yes, some netbooks will give you 6+ hours at half-brightness editing text documents… If you tried to do what Rohan described above on a netbook, you would simply fail because netbooks can not render HD video or play GPU/CPU intense games. If you play a standard definition video, I seriously doubt you can ever get more than 3-4hr from a netbook. And that’s with a 6-cell battery that makes your it weight at least twice more than Adam…

      In short, the only mobile devices that are able to perform a set of actions Rohan described here are full-blown laptops (and only some of them, btw, and that’s if we forget about the GPS). And performing them will squeeze the juice out of your laptop battery in an hour or so (at most two). So 6 hours of this kind of activity is a spectacular news, I don’t understand why everyone is whispering “disappointment”.

  4. suresh said, on October 29, 2010 at 12:38

    Great….Nothing to hide nothing to worry

  5. bob said, on October 29, 2010 at 12:39

    Very disappointing but to be expected.

    • iamapirate said, on October 29, 2010 at 18:04

      What is? That you can discharge your adam in 6 hours? Would you really want to watch HD 1080p from 10am to 4pm straight? I wouldn’t. I’d maybe watch a film, but then that’d be it – and it’d get charged nightly anyway (well, if it needed it)

    • KShu said, on October 29, 2010 at 21:04


    • bob said, on October 30, 2010 at 05:04

      I meant the blogs taking what Rohan said out of context. Sorry i didn’t clarify. Now they’ll probably say he’s backtracking on his promises, which I don’t think he is so far i’m really impressed by the effort Rohan seems to be putting in. In fact 6 hours is actually pretty epic compared to most other devices, and thats without PQ.

    • iamapirate said, on October 30, 2010 at 15:57

      @bob: ahhh ok, that makes more sense now!
      @KShu: shut it! :P ahah

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