Throttle timer in Taranis measures time based on throttle level. It can used to “guess” when you should land without monitoring current draw or voltage of the battery. In this tutorial I will show you how to setup Throttle Timer in Taranis TX.
This tutorial should work on any OpenTX compatible radios including the Taranis Q X7, X9D, Horus X10 and X12.
Don’t forget to check out our many other Taranis Tutorials and Hacks.
How Does Throttle Timer Work?
The throttle level determines how fast the timer runs. At 100% throttle, the timer runs at full speed while at 50% throttle it counts at half speed. At 0% throttle the timer simply stops. So basically, the more you use your throttle, the faster the timer goes.
I really like the idea of throttle timing, especially for little micro quads and Tiny Whoops. It’s common that they don’t have voltage monitoring, not to mention current sensor. A simple throttle timer is perfect.
There are two different throttle timers in the Taranis:
- TH% – timer counts down to 0
- THs – timer starts at 0 and counts up
We will be using TH% in our tutorial.
Limitations
Throttle timer is not as accurate as monitoring voltage and “mah drawn” directly, because it assumes throttle level is linear with current draw. In reality current draw actually goes up much more quickly with throttle.
But assuming you are fairly gentle with throttle, and with some calibration, it can give good result and still be better than using a simple timer.
It actually shares a similar concept to “virtual current sensor” in Betaflight and Cleanflight in case you are interested.
Determining Flight Time at 100% Throttle
First of all, we need to find out the flight time at 100% throttle.
It’s impossible to fly your quadcopter at full throttle for a whole battery, this will probably either kill your battery, your ESC or Motors.
So we basically have to guess… Then we can keep tweaking it to improve our estimation.
Calculate the Initial Estimation
If you know the maximum current draw of your motor and prop combination at 100% throttle, you can calculate the flight time using
Time = Battery capacity / Current Draw
For example, for a 1500mAh battery, and 80A of current draw at 100% throttle, the flight time would be 1.5/80 = 0.01875 hours = (0.01875 * 60) mins = 1.125 mins.
You can also look up motor thrust test data, but generally they are higher than what you would expect in real life, therefore you might want to reduce it by 20% to 25%.
For example for a motor and prop combo that draws 30A at 100% throttle, reduce it to a more realistic number such as 30*75% = 22.5A.
I don’t know the Amp Draw, What to do?
If you don’t know the current data about your motor, you can just time a gentle flight until the voltage alarm goes off. Then use 1/2 or 1/3 of that as your first guess for 100% throttle flight time.
For example, if your flight time is 4 mins, the estimation for 100% throttle flight time would be 4mins * 50% = 2 mins.
Setup Throttle Timer in Taranis
Once you have the flight time figured out, we can now setup the timer in the Taranis.
Go to the Model Setup page, scroll down to Timer 1. choose TH% as your first option, and enter your flight time there.
Now as soon as you move your throttle, the timer will start counting. To reset it, long press the enter button, select “Reset“, and “Reset Timer 1“.
Tweaking Flight Time
To improve the accuracy of your flight time, you will have to tweak it. Ideally the timer should end when the battery reaches 3.6V per cell. It’s not 3.5V because it’s better to leave some margin for error. The process will involve constantly landing your quad and checking voltage.
Unfortunately, throttle timer doesn’t work well if you have multiple varieties of battery capacity. If you have a different size battery you will need to adjust the flight time.
Setup the disarm switch to reset timer
You can use your the disarm switch to reset the timer, and it only takes 1 special function.
