For Jeti Transmitters with Lua
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Graphic and numerical representation of Jeti Centralbox and similar dual-power supplies.
Warning for exceeding or falling below threshold values.
Here is an example of the power supply for a large glider. Two LiFe batteries with 2S are used. Similar to a LiPo tester, the capacity of the batteries is displayed in percentage. This percentage is calculated based on the voltage and is independent of the settings in the box. It is a current state! Furthermore, the individual supply voltages and the average cell voltage (calculated!) are displayed. The inputs for the number of cells and the alarm are shown in purple.
In the lower part, the current consumption is displayed, summed up as well as individually for battery A and B. In the bottom right, the display shows the maximum measured total current of a flight.
Acoustic warnings:
- High current at power-up (blocked landing gear, etc.)
- High continuous current (for approximately 1.5 seconds)
- High current peak
- Voltage alarm for receiver battery
The first time the alarm value is undershot, an audible announcement is made. If the second battery falls below the threshold, an additional warning tone is added.
Limitation
Lithium iron and lithium-ion batteries have the property that they maintain a constant voltage over a wide range. In addition, the voltage measurement of the Centralbox is only accurate to one-tenth of a volt, which means that the display between approximately 30 and 90% is very rudimentary, while with lithium polymer batteries, the trend is displayed very nicely. Nevertheless, the display is much more meaningful again below about 30%, and therefore still of great use.
Installation
Download: Downloads English
Basic installation as described here, then:
Select “calca-Box” in the main menu.
Choose power supply for the two inputs. It can also be selected as BEC or None. If using a BEC, set the cell count to “1”.
Select at what capacity the warning should be triggered.
Select sensors for voltage and current. For alternative dual-power supplies such as Powerbox, only voltage sensors can likely be chosen.
Choose threshold values (warning thresholds) for current. Warning will occur immediately for startup and peak currents, with a delay for continuous current.
An example from practice: The power supply consists of a LiFe battery and the ESC’s BEC. The orange color of the display occurs 5% before reaching the alarm threshold; otherwise, no warning is issued.
The LiFe battery is now red; a warning was issued at 25%. The BEC turns orange when below 5 volts and would trigger the final warning with a preceding warning tone if it falls below 4.8 volts.
Practice
The alarms are discrete, so it’s a good idea to try them out first by intentionally setting the thresholds too tight. Only the alarm for “High Startup Current” is sharp because it could indicate a blocked servo. Typically, immediate action must be taken.
During flight, I occasionally hear the warning tone for high peak current when I execute a fast roll at high speed. Similarly, the warning for high continuous load comes when I fully extend the butterfly and am still a bit too fast.
Once everything is set up and working, you can adjust the thresholds to be more realistic so that no warning tones occur during normal flight.
Enjoy using the app!