Spirit System

Dear all.
Maybe someone with more LUA expertise can helpe me.

Getting Main Battery voltage telemetry via Spirit ESC integration is great, however if I have mixed heli settings with different cell counts from 3S to 6S, 8S and 12S, therefore absolute Battery value don't tell me to much during flight but I would rather get average cell voltage reported, like 3.6V.
Having said, I started to look into LUA to get this solved. However I could not get any meaningful output.
Using mixed Scripts, I took RBV1 which reports 22.91V as input, asked for numbers of cells (6) to calculate output, but get value like 0.2 not even close to expected 3.82V. Beside, if I use like a Stick as Input it works 100/6 = 16.7.
What am I doing wrong here. Plan is to use this calculated average value as alarm trigger for announcement.
Any help is appreciated, many thanks.

SCRIPTS/MIXES/avcell.lua

-- Calculating average cell voltage from Main battery --
-- by Adrian May 2020
-- This script will ask user for number of Main Battery cells
-- based on reported Telemetry it calculates av. cell voltage

-- Selection of Telemetrie Source and number of cells used
local inputs = { {"Tele Source", SOURCE }, {"Number Cells", VALUE , 1, 14, 6 }}

-- returning the average cell voltage
local outputs = { "vcel" }

-- Calculating the average cell voltage
local function run(voltage, cell)
local avCel = voltage / cell
return avCel
end

-- Return statement
return { run=run, output=outputs, input=inputs }

Well, dived a bit more into it, I figured out that mixes are using 16-Bit signed integer doing division of 10.24 at the end to match 1024 to 100%.
return avCel * 10.24
Multiplying return by 10.24 gives correct value, however with mixes, I can't solve it, as there is also no decimal used. 3.4V eq. 3V

I'll investigate more, currently I'm thinking of using telemetry background function.
If someone has an idea or working script, let me know.

Thanks, Adrian

Finally I did manage it, by using a mixed Script with direct voice prompts to alert pilot.
This allows user to enter some parameters like cell count, telemetry source, voltage trigger level and alarm interval.

Load script onto SD Card SCRIPTS/MIXES
Enable it by adding it in the LUA Screen in your Transmitter.
There you should set parameters and see some values.
It requires telemetry to work.
Try like RxBt and Cellcount 1 to trigger alert, now select right source, like RB1V for me with HW ESC.

I did add some comments into the lua script to explain, feel free to use, play and change.

As *.lua extension is not allowed to upload, change it from .txt to .lua once downloaded.

Have fun, Adrian

I don't know enough about LUA scripts to comment on yours I'm afraid, but I thought that you might like to know that there are other ways of doing this using Special Functions - I used this approach from Oscar Liang https://oscarliang.com/taranis-logical- ... age-alarm/ - it includes some clever ideas like setting a timer for the low voltage alarm so that it needs to be below a specific value for a certain time period - that way you don't get lots of warnings on power climbs where the extra draw might drop the voltage momentarily.

I use this on different helis with 3, 4 and 6 cell batteries and just change the trigger voltage level for different helis, this wouldn't work if you used different sized batteries on the same heli though..

I'm not saying that yours isn't a good approach, just showing an alternative..

Hi Mikej, your absolutely right, this was the way I did it and it worked great.
However I missed a clear statement on cell voltage. With different cell packs on different birds it was hard to tell how bad the level was without doing the mental arithmetic. That's why I came up with it, as cell voltages tells me more than pack voltage. I' absolutely with you. No need if you just wan't a low battery alarm.
I might think about implementing the delay as well, this is a great point you mentioned. Once ready and tested, I'll share. Thanks for your input.