Hi people,

    i'm playing with these great ZigBee modules from Maxstream (XBEE). 
They are really interesting and powerful..

    My problem is related to battery life.

    According to the manufacturer battery life calculator available at:

    http://www.maxstream.net/support/battery-life-calculator.xls

    i could have a life of more than 3 years depending on the conditions 
i use my modules. Well, my conditions are quite good:

    - The module is in sleep all the time, waking up each 4 minutes, 
sampling ADC ports, transmitting data, and going back to sleep

    Theorically i should get at least a year, but when i tested it, my 
batteries did not last for 2 months! I'm using 2 alcaline AA batteries 
which gives 3V.

    Well, seems like the batteries still have energy, but their tension 
has gone to less than 2,7v, which will not power XBEE.

    The problem, is that there are no commercial batteries available 
with 2000mAh and 3 ou 3,3V with low voltage drops in the long time.

    Some engineers suggested me 9v batteries with a voltage regulator.

    Is it a good idea? Won't i loose too much in the voltage conversion 
(9-3=6v). At 50mA i'll spend 300mW just to drop the voltage???

    Well, i really don't know how to manage the batteries to give me 2 
years of life to my little remote sensor.

    Does anyone have any idea or clue?

    thanks a lot

Rafael
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