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Reply To: Monitoring power consumption

Home Forums Mayfly Data Logger Monitoring power consumption Reply To: Monitoring power consumption

#14656
neilh
Participant

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.
https://github.com/neilh10/ModularSensors/wiki/Test-equipment-cable-monitor-LiIon

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)
https://github.com/neilh10/ModularSensors/wiki/Test-Equipment-FTDI-cable

Using this arrangement, sampling every 2secs to get an idea of the instantaneous current
https://github.com/neilh10/ModularSensors/tree/release1/tools/current_logging

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