Estimated Battery Lifetime

The resulting solution must run on batteries (coin type ideally) and I wanted to get a sense of the operating time between battery changes.  The spreadsheet utilized the cells in red as variables. Assuming a wake up during of 30ms and sending a sample every 100 seconds, I can run for an acceptable amount of time.  The problem occurs when I include a 78L33 level converter, 555 timer, and a sample sensor like the LM35. I will need to look into this as this might be a show stopper on the battery only constraint.


I have set up my test circuits to using a 555 timer and create a 99% duty cycle for a duration of 100 seconds or so. It does wake the xbee up and transmits to the host software. Now I need to re-evaluate things from a power consumption side.

I will measure the actual current when I build the prototype.

Device Current
Xbee Sleep 0.01 mA
Xbee TX 45 mA
Xbee RX 50 mA
Battery 200 mAh
555 timer 0.1 mA
LM35 0.06 mA
78L33 5.5 mA
Level Converter (5 to 3.3 V)
Sleep Period 100 seconds
Tx 1 per wakeup
Rx 1 per wakeup
Wakeup Duration 30 ms
Aprrox Wakeups per 24 hr 864 count
Approx wakeup duration per 24 hr 25920 ms
XBee Current per wakeup 95 mA
Xbee mA per 24 hours consumed during wakeup 0.684 mA
Xbee mA per 24 hours consumed during sleep 0.009997 mA
mA per 24 consumed 555 2.4 mA
mA per 24 consumed LM35 1.44 mA
mA per 24 consumed 78L33 132 mA
# of days for one battery w/o 78L33 44.0 days
# of days for one battery 78L33 1.0 days
# of days for one battery w/o 78L33,555, LM35 288.0 days