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Horus X10 transmitter voltage low warning level

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Geoff S08/09/2019 21:11:43
3666 forum posts
26 photos

I was having an enjoyable flight with my DB Gypsy Moth this afternoon when I was forced to abort when the bossy young lady who lives in my Horus told me in no uncertain terms that the transmitter battery was low.

Of course I landed immediately and I never lost contact but I checked the level of the warning and it's currently (or perhaps voltagely) set to 7.1 volts. I'm not sure if that's what I set when I first got the transmitter or if it's the default.

What level do others have? When I checked the voltage reading on the transmitter itself it still had 2 bars (out of 4 IIRC).


John Privett08/09/2019 21:57:00
6049 forum posts
242 photos

Geoff - mine's set to 6.5v.

I honestly don't recall if I changed it or if that is the default. It's never given me an alert whilst flying and I charge the tx 'every now and again' - usually when it gets down to about 2 bars. It's showing 6.8v and 2 bars right now after a couple of lengthy slope sessions and a few power-model sessions since last charged. I'll pop it on charge now!

Geoff S08/09/2019 22:44:47
3666 forum posts
26 photos

I've just recharged it and it seemed quite quick - just about 2.5 hours. Never had the warning before but I'm only too aware that Lithium batteries (these are Lithium Ion 2S 2600 mAH so nominally 7.2v) can fall off a cliff at a certain point and I'd rather that not happen with a model in the air.

I think I'll stick to 7.1 for now.


Tim Ballinger09/09/2019 08:41:50
792 forum posts
290 photos

Mine is set at 6.5V , as the default setting when I received it. Never had it alarm and not sure I have ever let it go below 2 bars. Seems to last for ages but I don’t actually keep a log.


Masher09/09/2019 09:13:09
1106 forum posts
79 photos

Mine is set at 7.1V. Below is a plot from an actual X10S (not mine although mine is very similar) it clearly shows the difficulty in setting realistic alarm levels for this type of battery. I rarely fly for more than a few hours and charge every time anyway (force of habit) so no issue for me. IMHO 6.5V is living on the edge!

x10 volts.jpg

Edited By Masher on 09/09/2019 09:14:26

Denis Watkins09/09/2019 09:18:48
4449 forum posts
113 photos


You make this point very clearly Masher

Geoff S09/09/2019 11:19:57
3666 forum posts
26 photos

Thanks for that curve, Masher. It illustrates my 'falling off a cliff' analogy very well. It looks like my 7.1v is ultra safe and I may knock it back to 7.

I checked the state of charge on Saturday evening. It looked full and I mistakenly thought I'd recharged since I'd last flown. At least all it did was force me to abort the current flight and come home an hour earlier than I would have.

There's an option to calibrate the voltage measurement (I'm using Open TX) but I couldn't immediately see how it worked or how to do it and it was too late last night. It was reading a tad over 8v (8.18 IIRC) but it could be varied with the RH display control. Seemed odd but I'll look into it further today. I'd like to display the actual number rather than the hard to see bars but I'm not sure if that's an option.


Tim Ballinger09/09/2019 11:44:22
792 forum posts
290 photos

I have a switch set which gives a speech readout of tx (pos 1) and Rx volts (pos 2) from the Telemetry data. It is also in the parameters displayed if I cared to page through or set it at a higher priority so that it comes on the main screen.

In reality I rarely check while flying and rely on the voice alarms. Only ones that ever go off are for the lipo if I use full power after my timer has gone off ! All are set very conservatively so as to give me time to circuit and land.

i got concerned the other week when the ESC temp alarm went off but when I checked on the ground I had the value set to 45 Reg which in reallity is not very high so I reset it too 65 Deg which I think is ok but if anyone knows better then please shout.


Masher09/09/2019 11:50:05
1106 forum posts
79 photos

Yes you can display actual Tx volts - takes some finding but the option is there:


Torsten Spitzner09/09/2019 16:14:33
34 forum posts
21 photos

Mine is set at 7.2v , as i bought it. ( NIB) . I'd rather have it set too high than fall off the voltage cliff..

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