Saving battery life

Discussion in 'Hardware' started by blblblbl, May 31, 2006.

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  1. Daring

    Daring Moderator

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    There seems to be a great deal of interest in watching DVDs on tablets/notebooks. My experience has been that getting 2-3 hours of time out of a notebook while watching a DVD is pretty good. However I regularly get 4-5 hours of normal use when not using a DVD.

    By ripping the DVD to my HD, I am able to get 3-3.5 hours, about an hours savings. This got me thinking, that at least part of what is eating my battery life is the constant spinning of the HD. By converting to DivX a two hour movie can be reduced in size to about 800M-1G. This is small enough to fit entirely in RAM with the OS loaded (I have 1.5G).

    So here is my question (I know you've been waiting ;) ), is it worthwhile to set up a RAM disk of some sort to copy the file in there and then play it from the RAM disk. This way the HD could spin down.

    I'm not interested in going through this exercise to get another 10 minutes. If it will consistently push me over the 4 hour mark it may be worthwhile. I really don't want to invest a ton of time in this if the general consensus is that the savings will be negligible.
     
  2. Brian

    Brian Scribbler - Standard Member Senior Member

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    Geez, I don't know but I can't imagine the benefit would be worthwhile. You'd see more impact by turning your backlight down a notch. Also consider disabling your wireless radios, that would have a tiny benefit.
     
  3. Dustin

    Dustin Pen Pal - Newbie

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    You must have a gigantic harddrive, if you really want to squeeze out some more time you might want to try useing headphones and as brian said turning the screen brightness down.

    If your really ambishous on this idea i guess you could put the DVD on a portable flash card, then your harddrive wouldnt have to spin at all.
     
  4. Daring

    Daring Moderator

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    Gigantic hard drives really aren't required. As I mentioned, when you convert a 2 hour DVD to DivX it only requires about 1G. This means I could have 20 hours of watching in <= 10G.
    Headphones already in use (the sound out of the speakers really isn't that great and would disturb my fellow passengers), screen brightness depends on setting. In airport terminal 75% on plane 50-60%.
    No need. The idea was to load it on a RAM disk and use the computers memory, which I am already taking the hit for anyway.
     
  5. cochise

    cochise Pen Pal - Newbie

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    I usually only get 2-3 hours of DVD time on my tablet as well...that usually is enough for me. But I suppose if you wanted more time you should first start out by dialing down smaller steps, like the dimness of the light like mentioned. If you have an idea to get the job done better...I would suggest trying it out and seeing if it works firsthand.
     
  6. Gautam

    Gautam Moderator

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    This is a question that techies have tusseled with for years.

    The bottom line is that the energy consumed in reading/writing to optical discs (CD,DVD,etc) will always be higher than to a hard drive (magnetics discs stacked on a platter)

    In order to get improved battery life, you could definitely watch movies from your hard drive as opposed to from a DVD. HOWEVER, you would only get a trivial battery consumption difference between an uncompressed and compressed DVD (compressed via DivX, etc). The only reason you would compress a DVD is to save space.

    There are also a suite of battery monitoring programs available, many of which do interesting things apart from the normal screen dimming, processing speed reduction, etc.
     
  7. nfwolfpryde

    nfwolfpryde Scribbler - Standard Member

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    Daring, making a RAM disk sounds like a great idea actually. What you're trying to do is make a machine with that won't access the HDD while watching the movie, which is a tremendous battery hog.

    But... you have to have the laptop on. All the time. It's erased as soon as you shutdown. So you'd have to rip/encode/watch the movie in one whole sitting. Unless of course you just have a database of movies (No doubt all obtained legally), and you copy a movie from your HDD to your RAM drive and THEN watch the movie. That sounds doable.
     
  8. okashira

    okashira Scribbler - Standard Member

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    sounds like a reasonable Idea. or you could just use a flash drive.

    I'm assuming you've undervolted your cpu?
    run your (pentium M?) forced at 800mhz and 0.7 V should net you at least another 30 minutes.
     
  9. blblblbl

    blblblbl Pen Pal - Newbie

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    but how're you "ripping" the DVD? are you copying byte-by-byte or encoding it to some other format?

    if you're doing encoding or compression at the same time, it could take quite a bit of cpu power... thus draining the battery...
     
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