Battery monitor feature v2 - based on INA219 Current&Power Monitor

[gvidinski]

I'm presenting you the new version of Battery monitor feature. It allows you, if UPS topology is used to power the board, to monitor the state of the battery by showing current battery voltage in mV along with it state in percent, current draw in mA and power consumption in mW(W).

This solution relies on TI INA219 Zerø-Drift, Bidirectional Current/Power Monitor IC With I2C Interface and can be used by simply attaching to the configuration an Adafruit INA219 Current Sensor Breakout board (Figure 1) or some of its clones.

Figure 1.

The UI is organized in the following manner. The feature can be enabled through the "Configuration" page. All the settings for the Battery monitor have to be entered form the “More settings” tab, under the “Enable battery monitor” checkbox (Figure 2).
When enabled (Figure 3) user may choose from a drop-down (Figure 4) between tree calibration settings already predefined by the Adafruit INA219 library, depending on concrete setup - 32V/2A, 32V/1A & 16V/400mA. But most important, in order to receive correct battery state percentage, the user will have to set the threshold voltage for both, the discharged [Battery U min (mV)] and the fully charged [Battery U max (mV)] state.
Then the actual battery state can be obtained at the “Device status” page (Figure5) in the form of “Battery status: -.--mV | -%”, "Current draw: ---mA" & "Power consumption: ---mW" (Figure 5.).

Figure 2.	Figure 3.
Figure 4.	Figure 5.

All the measurements are done by averaging 3 consecutive readings taken in periods of 1 second, then followed by 10 seconds pause period. In addition the Battery state data is added to the json result. This way users can track the state of the battery and also may develop customized battery state charts on their platforms.

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Build and testing was done using the PlatformIO under the Visual Studio Code IDE following the “Contributing Guidelines”.