Battery Life Estimation: First try

Richard A. Smith richard at
Fri May 2 16:24:10 EDT 2008

Over the past week or so during my walk to and from 1cc I've been
pondering about about battery life estimation.  I've also had a
conversation with a G1G1 user who made me realize that it really doesn't
even have to be that accurate.  It just has to be reasonable.

Since my power logging script already had most of what I needed, I
added the ability for it to make lifetime estimations based on the the
ACR readings.  Its a pretty simple first guess.  Comments and/or 
improvements welcome.

This script does 2 different ttl calculations every loop.  One is based
on the ave current draw from the start of the script and the 2nd based
on the power draw since the last loop.  My initial loop time was 60 seconds.

Since its in log format I can compare the estimations vs reality.  Using 
the time from the start of the script until the time that the EC reports 
LOW as the official marker I'm getting errors ranging from 66% to 1%

The script is available at:

Richard Smith  <richard at>
One Laptop Per Child

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