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Reply To: Monitoring power consumption

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    I’ve been using the INA219 and contributed sensors\TINA219
    I’ve used it for measuring a working Mayfly on the lab bench. For  field monitoring, I would think you need a coloumb counter ~ eg LTC2941 ~ I have an adafruit version but haven’t tried it.

    On the lab bench I have the INA219 on a separate Mayfly with console and put in in series with the target systems LiIon battery.

    For measuring a working Mayfly current I disconnect all other sources of power, and even have a special version of the FTDI cable to plug into the FTDI debug (instead of USB data/power) with the Ftdi Tx cut (as its held high and leaks current)

    Using this arrangement, sampling every 2secs to get an idea of the instantaneous current

    There has been past discussion on Mayfly sleep current. IMHO I’ve got to be in reasonable shape, but perhaps not meeting what a calculated minimum suggests it could be. https://github.com/EnviroDIY/EnviroDIY_Mayfly_Logger/issues/21

    I figured for reliability of systems in the field a software based Battery Management System was more viable than trying to tweak down the sleep current. The target is reliable data collection, and reliable delivery for low cost LiIon/4Ahr battery and solar panel/5W.  Note the Mayfly Vbat monitor becomes non-linear at about 3.6V

    The figures I got for Mayfly sleep was 2~4ma.  I have some notes that when I started taking measurements it was about 5mA. I did some tweaks got it down. Here are the measurements I made in my log with a Digi Xbee WiFi.
    <h3>2018Dec12 sleep Current readings</h3>
    with INA219 monitoring from another Mayfly
    1st time through from RESET
    02:13:24.972 mA: 3.80, V: 0.908
    02:13:26.971 mA: 1.90, V: 0.936
    02:13:28.972 mA: 2.10, V: 4.048
    02:13:30.973 mA: 7.70, V: 4.044
    02:13:32.972 mA: 4.00, V: 4.048
    02:13:34.999 mA: 3.60, V: 4.048
    02:13:36.999 mA: 38.20, V: 4.020 <sensors starting

    02:13:38.999 mA: 38.20, V: 4.024
    02:13:40.999 mA: 38.20, V: 4.020
    02:13:42.999 mA: 38.20, V: 4.020
    02:13:44.999 mA: 38.20, V: 4.020
    02:13:46.999 mA: 105.30, V: 3.972 <1st time Xbee including setup
    02:13:48.999 mA: 90.00, V: 3.972
    02:13:50.999 mA: 107.20, V: 3.968
    02:13:52.999 mA: 106.80, V: 3.968
    02:13:54.999 mA: 107.20, V: 3.968
    02:13:56.999 mA: 106.70, V: 3.968
    02:13:58.999 mA: 53.80, V: 4.000
    02:14:00.976 mA: 107.50, V: 3.964
    02:14:02.977 mA: 121.90, V: 3.964
    02:14:04.976 mA: 106.80, V: 3.960
    02:14:06.977 mA: 106.80, V: 3.964
    02:14:08.977 mA: 106.40, V: 3.964
    02:14:10.976 mA: 121.10, V: 3.960
    02:14:12.977 mA: 106.60, V: 3.956
    02:14:14.978 mA: 107.40, V: 3.956
    02:14:16.979 mA: 3.60, V: 4.028    <off sleep
    02:14:18.978 mA: 3.60, V: 4.032
    02:14:20.979 mA: 3.60, V: 4.032
    02:14:22.980 mA: 3.60, V: 4.036
    02:14:24.978 mA: 3.60, V: 4.03