Flat battery before flight – warning

(I wrote this in finnish to kopterit.net-forum and was pointed out that it could be added here also.)

This is well known, useful alarm for Jeti, found on various forum’s in the world wide wait. This is just my view on it.

It happens really easy that You connect a empty or half-empty battery to Your model and go flying. This ends rarely in happy feelings so why not create an alarm for it.

What we need is a way to monitor battery-voltage only a few moments after plugging it in. We can’t keep this alarm active the whole time since the alarm-threshold needs to be relatively high.

So, here it goes, in few simple steps.

This method does not work in every configuration, for example speed on sensors and/or your beep-code usage might interfere with this way. You should try second method in that case, found here.


Make a telemetry-control that activates when battery-voltage is for example over 5 volts:


Make a sequence (For me it’s Q1) that is active (100%) only a few seconds, define the switch as the telemetry control You just did (for me that was MX1)


Make sure in the Advanced-side to choose”Asymmetrical” and “Always finish the sequence”


Make a another telemetry-control, choose the threshold as  “cell-count x 4.1”. This means that if the battery’s cell-voltage is lower than 4.1 volts (LiPo) we judge it as used and not fully charged. Remember to choose right condition “X <” also put the duration as 0.2 seconds.


For this telemetry control define the switch as the sequence You just made (For me in this case Q1) and remember to define it as reverse.


Lastly define a warning for this in “Sounds on event”, the activating switch is the second telemetry control You made.


You can see in the picture above I have the same event three times with different delays. I get the warning three times with 2,5 second between them. This is not a necessity.

Extra safety when using LiPo’s is never a bad thing, this also prolong’s the life-expectancy of Your batteries :)

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