|Re: 15C Reissue is actually a carefully disguised printer?|
Message #5 Posted by Katie Wasserman on 24 Aug 2011, 12:15 p.m.,
in response to message #4 by Michael de Estrada
What is the battery life on the 12C+ ?
So-so. Here are my approximate current measurements:
OFF = 0.004 mA
ON/idle = 0.05 mA
ON/running AMORT or tight loop = 20 mA
The two CR2032 cells have a combined capacity of about 450 mAh (depending on brand) at a standard current draw of 0.2ma. So the OFF state current draw is fine, implying a "shelf life" of 12 years.
The ON/idle state implies a lifetime of about 1 year, still pretty good.
However the running time is horrible, since the capacity of these cells drops precipitously beyond their standard rating of .2 ma. Manufacturers don't rate these to work at 20ma, so I can only guess (or test, I suppose) the capacity at 20ma. If I had to guess I'd say it's about 40mAh. Giving the calculator about 4 hours of continuous run-time use -- it might be less than this.
If you're not running "loopy" programs however, the quick 20ma current burst won't kill the batteries nearly as fast as a continuous draw. So basic math functions should allow for decent battery life.
Edited: 24 Aug 2011, 12:15 p.m.