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Battery capacity calculation

Battery capacity calculation. For example. Example Non beacon Star network JN5139R1 Binary size = 16kbytes Continuously performs the following actions a. wakes from sleep b. Reads data from a sensor via I2C interface c. performs a clear channel Assessment (CCA)

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Battery capacity calculation

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  1. Battery capacity calculation

  2. For example • Example • Non beacon • Star network • JN5139R1 • Binary size = 16kbytes • Continuously performs the following actions a. wakes from sleep b. Reads data from a sensor via I2C interface c. performs a clear channel Assessment (CCA) d. transmits a data frame containing a payload of 64 bytes e. sleeps (without holding the memory contents ) for 10 minutes f. go to (a) I = Q/V [amp] or Q=I t [coulomb]

  3. For example • Waking from sleep oscillator start time = 2.5msec Application load time = 0.84 per 1kbyte time to wake from sleep = (0.84 x 16 ) + 2.5 = 15.94 msec when loading the binary, current = 9 mA total charge = time to wake from sleep( 15.94 msec) x loading current(9 mA) = 143.46 uC • Read data from sensors when read sensor, current = 9 mA reading time 5 msec total charge = reading current ( 9 mA ) x reading time ( 5 msec ) = 45 uC • Performs clear channel assessment ( CCA ) BackoffPeriod ( ms) = ((2 x 2) -1) x 20 / 62.5 = 0.96 ms CCA Period ( ms ) = 0.128 ms Rx radio receiver currrent = 34 mA CCA charge = CCA period ( 0.128 ms ) x Rx radio receiver current ( 34 mA ) = 4.352 uC CCA back-off charge = backoffperiod ( 0.96 ms ) xRx current ( 12.8 mA ) = 12.29 uC

  4. For example • Transmitting Data Data Frame Transmission Period (ms) = (HeaderSize + PayloadSize ) x 8/250 Data Frame Transmission Period (ms) = ( 15 +64 ) x 8 / 250 = 2.528 ms total charge = Data Frame Transmission Period ( 2.528 ms ) x Tx radio current ( 34 mA ) = 85.952 uC • Sleep sleep current = 0.0013 mA sleep time = 10 minute – transmitting time = 599975.444 msec total charge = sleep current ( 0.0013 mA) x sleep time ( 599975.444 msec ) = 779.968 uC • Total charge wake from sleep + Read sensors + CCA back-off + CCA + Transmit data + sleep total = 1071.022 • Average Current per second Average Current = total charge consumed / time = 1071.022 / 600 ( 10 minutes ) = 1.78 uA • Calculation capacity capacity = I average x T runtime capacity = 1.78 uA x ( 50years x 365days x 24hours) = 779.64 mAh • Conclusion in normal case, AAA battery has a 1000 mAh, so battery life time will be expected 50 years.

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