How to determine the current consumption for a device like xbee? which draws 120mA current when transmitting only.Rest of the time it takes 1mA.

In our application the xbee transmits 5 packets per hour.the transmission time is 1second/ transmission.

How to determine the average current of the xbee per hour ? if considered, the xbee works as the above said scenario.

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    \$\begingroup\$ You forgot to ask a question. What's the problem? \$\endgroup\$ – Transistor May 13 '18 at 13:32
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    \$\begingroup\$ 5 times each hour. For how long each of the 5 times? \$\endgroup\$ – Marla May 13 '18 at 13:39
  • \$\begingroup\$ Still no question after your edit. Just a question mark in the wrong place instead of an 'r'. You still haven't explained what the problem is or where you are stuck. \$\endgroup\$ – Transistor May 13 '18 at 13:44
  • \$\begingroup\$ 1 second is the time it takes to transmit. \$\endgroup\$ – Shiv May 13 '18 at 13:45
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    \$\begingroup\$ @Shiv that is not a question. You must ask a question. \$\endgroup\$ – Marcus Müller May 13 '18 at 14:17

It seems that you are stuck with the mathematics and not the electronics.

Information given:

  • Quiescent current: 1 mA.
  • Transmit current: 120 mA.
  • On time per hour: 5 x 1 s = 5 s.

Other factors:

  • Seconds per hour: 3600.

Average current:

$$ I_{AVG} = \frac {I_{ON} t_{ON} + I_{OFF} t_{OFF}}{period} = \frac {120 \times 5 + 1 \times 3595}{3600} = 1.16 \ \mathrm{mA}$$


There's also a possibility to measure the average current, which is especially useful if you're unsure about the numbers. There are existing tool for this task you can buy (power meters, data loggers with current sense amplifiers) or you could build your own using a cheap MCU with an analog input and an opamp. Of course, if you build your own tool, you will need to extensively test and calibrate it before use.


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