And if you dont want to mess around with hardware you may use either
PowerTossim or Avrora to estimate energy usage for each sensor node. You can
later on use the hardware options to verify if you like.

On 1/20/07, Michael Schippling <[EMAIL PROTECTED]> wrote:

I didn't know about that chip...pretty cool, but will still only
approximate things based on some set of 'ideal' conditions. I'm
sure we've all had the low-battery warning on some device happen
at seemingly random times before full failure...

But there is a nice app-note on using voltage as a charge indicator:
http://www.maxim-ic.com/appnotes.cfm/appnote_number/121

thanks
MS

Jacob Sorber wrote:
> If you aren't afraid of a little hardware work, you can also use a fuel
> guage IC like the DS2770 from Maxim/Dallas.  That will give you better
> accuracy, if you really need it.  If you approximate battery energy
> using voltage, just keep in mind that it is not linear and that it is
> different for each battery.  You should either check the battery specs,
> or estimate the curve experimentally.
>
> Jacob Sorber
>
> On 1/18/07, *Michael Schippling* <[EMAIL PROTECTED]
> <mailto:[EMAIL PROTECTED]>> wrote:
>
>     If you mean battery energy, you probably can't because there is no
>     provision for measuring current draw. You can approximate it with
>     the battery voltage and knowledge of the discharge characteristics.
>     I also recently suggested measuring the voltage before/during doing
>     something that draws a lot of current.
>
>     MS
>
>
>     paul jhon wrote:
>      > Hello,
>      >
>      > I need to compute the initial energy of the sensors
>      > and its remaining energy at every moment.
>      >
>      > Can you please tell me how to do this in TinyOS2.x?
>      >
>      > thank you so much for your answer.
>      > Paul
>      >
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