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Many of Digital Matter's new range of Battery Powered Devices (check them out on our website!) are fitted with a Battery Meter (Coulomb Counter).
This device tracks the energy consumption of the battery in mAh, and the device then reports this data to Telematics Guru.
Devices without a battery meter still report other statistics which are displayed in the battery management tool.
Due to the battery chemistry of Lithium batteries, it is hard to predict the remaining battery life accurately from battery voltage alone, and a 'Battery Good' flag is set or cleared on older devices, depending on the measured battery voltage, to allow for low battery alerts.
How does it work?
If we know the capacity of the batteries is 3000mAh, and the device reports it has used 1500mAh since the last reboot, we know the batteries are at 50%.
If the device has used 20% of it's battery in 20 weeks, this equates to 1% per week, and therefore we know that the total battery life is 100 weeks. From there we can say that there is 80 weeks remaining at the current usage.
This is obviously affected by device parameter changes.
When using the device in a new application, with a certain set of settings/reporting rate. A device can simply be placed in the field with the required settings and left running for 1-2 weeks. Then the predicted life time can be determined with greater precision than estimates based upon lab-measured device current draws, and guesses as to how often the device will actually be used.
Using the Battery Management Tools in Telematics Guru
To view battery statistics, head to Assets -> Battery Management. The user will require the "Manage Assets" permission to view this page.
You will be taken to this view:
The Grid is shown with asset information.
Devices that do not have a battery meter will not display a percentage or remaining capacity estimate, however the other data will be shown.
Click on the asset name (1) to view the device performance counters and battery percentage graph.
When not hovering over the graph, the current counter values are shown. However along the graph to display the counter values at that point in time. Red dots on the graph indicate a counter reset, which is generally due to a hard reset (devices removed and reinserted)
Sudden drops in the graph may indicate an issue. And comparing this to the counter values can help in debugging.
For example, if the Failed GPS fix value increases greatly during the time of increased battery usage, this could indicate the device may have been moved to a location with no GPS signal, and is using battery excessively due to attempting to get a fix for the full GPS Timeout period (generally 60s) on each attempt.
Click on the icon shown in (2) to open the Google Maps page of the device location.
Click on (3) to open the device in OEM Server
Click on (4) to view the assumptions made when calculating the battery percentage and remaining battery life, they are shown below:
Factors Affecting the Remaining Battery Estimate
Please take note of the following:
- Use the battery type recommended for the product. If there are different battery options for a product, the firmware needs to be set up for the different battery capacity.
- Do not mix battery types.
- Use brand new batteries. Counters are reset on a Power On Reset. Fresh batteries are essential for useful predictions.
- Cold temperatures will reduce the battery capacity, which is not accounted for in the device counters.
- Battery failure is possible. This is more likely in extreme temperatures.
- These predictions are based on average historical data for each device. Changes to device settings may result in performance that does not match the predictions.
Battery Management Reports
TG supplies many pre-configured reports as well as reports that can be customized. To view all reports, click on Reports>>All Reports.
TG supports a Remaining Battery Life Estimate report.
To schedule the Remaining Battery Life Estimate report begin on the dashboard by navigating to Reports>>Schedule Reports and click on 'new'. You are able to then select Remaining Battery Estimate Report in the drop down list of 'Report Type'. The schedule and recipients can be modified when editing this report. Once complete select 'save' and the report will be saved and can be managed in scheduled reports from the dashboard, Reports>>Scheduled Reports.
Schedule this report each week to ensure you are performing regular health checks on your battery powered devices, and catch small issues before they become big problems.