BangleApps/apps/batchart

Summary

Battery Chart contains a widget that records the battery usage as well as information that might influence this usage.

The app that comes with provides a graph that accumulates this information in a single screen.

How the widget works

The widget records data in a fixed interval of ten minutes.

When this timespan has passed, it saves the following information to a file called bclogx where x is

the current day retrieved by new Date().getDay():

• Battery percentage
• Temperature (of the die)
• LCD state
• Compass state
• HRM state
• GPS state

After seven days the logging rolls over and the previous data is overwritten.

To properly handle the roll-over, the day of the previous logging operation is stored in bcprvday.

The value is changed with the first recording operation of the new day.

How the App works

Events

The app charts the last 144 (6/h * 24h) datapoints that have been recorded.

If for the current day the 144 events have not been reached the list is padded with

events from the previous bclog file(s).

Graph

The graph then contains the battery percentage (left y-axis) and the temperature (right y-axis).

In case the recorded temperature is outside the limits of the graph, the value is set to a minimum of 19 or a maximum of 41 and thus should be clearly visible outside of the graph's boundaries for the y-axis.

The states of the various SoC devices are depicted below the graph. If at the time of recording the device was enabled a marker in the respective color is set, if not the pixels for this point in time stay black.

If a device was not enabled during the 144 selected events, the name is not displayed.

File schema

You can download the bclog files for your own analysis. They are CSV files without header rows and contain

timestamp,batteryPercentage,temperatureInDegreeC,deviceStates

with the deviceStates resembling a flag set consisting of

const switchableConsumers = {
 none: 0,
 lcd: 1,
 compass: 2,
 bluetooth: 4,
 gps: 8,
 hrm: 16
};