Lemon 7 ch stabilised receiver current sensor

[Brian Dorricott 1]

Let me start by saying I have nothing but praise for these receivers , great features and rock solid stabilisation regardless of setup , manual or textgen and who in the Spectrum world can complain at the price . Yes there's a " but " coming with the above regarding the current sense telemetry . I have only 3 working receivers that measure current and about 7 that don't,  before anyone suggests it I've swopped working XT60 connectors around and factory reset all the suspect ones and even used a different transmitter ( NX10,DX6G2 and TX16S ) all to no avail . Still resolutely refuses to show any current draw at all right up to a measured 30 amps on the ammeter . Everything else on the suspect ones looks good vario, altitude etc it evens finds current when I delete all telemetry and rediscover but stays on 0 amps on all 7 receivers . The 3 good ones will display from a few mAh to 10s of amps reasonably accurately and I know you can calibrate them but you have to have a display first ! It's not going to stop me using them because the basic functionality is fine and I only want to know what current I've used on my EDFs which eat batteries otherwise its not really necessary. Anyone used these a lot and knows of any foibles quirks etc that may help.

Just as an aside they are all later models with textgen and some were bought with the XT60 current sense together ??? Wonder if there are different software versions must check the software versions when I've an hour to spare.

[Outrunner]

Brian, have you tried asking your question over on RC Groups Lemon users thread? RC Groups there are some Lemon specialist who should be able to help.

 

I've only used the voltage sensors on the 7 and 10 Ch receivers with no problems.

 

It will be interesting for future reference as to what is causing the problem.

[Brian Dorricott 1]

No but i will do !

[Brian Dorricott 1]

Ok sorted now . I despite never having been in the calibration screens had to calibrate each one separately for current and voltage . I would have thought out the box they would have worked on or about the ball park but not showing anything . I can understand the one where I factory reset it but the others , no idea . Thanks anyone for thinking about it .

[Outrunner]

Good news you are sorted.

I've tweaked the telemetry voltage readings before but they are never so far out they don't work 

I'll have to remember that one if I get any current sensor's.

 

 

[Frank Skilbeck]

Brian, where can I find how to calibrate the current sensor, I've got one and it under reads.

[Outrunner]

Frank. If you visit the Lemon RC https://lemon-rx.com/manual they have excellent documentation for all of their products.

[Brian Dorricott 1]

Fairly easy to do Frank if you have the later Textgen ones , voltage needed 8.4 volts so fully charged lipo and a load of 4 amps for the current . If you want a quick and dirty test a 55 watt 12 volt headlamp bulb draws about 4.5 amps . I being a bit of perfectionist set mine spot on but used esc/motor/battery/wattmeter and a servo tester with the current sensor in line and started it until I read 4 amps then calibrated the Lemon which was on a separate battery but I had 5 receivers to do .

You can do the same by pushing the buttons on the Lemon if Textgen isn't available but looks a little fiddly for sausage fingers me !

Couple of things if you have a well equipped man cave , use a bench power supply to do the 8.4 volts so its exact. For the current sensor I found some high power resistors to get 3 ohms and varied the volts on bench power supply to get exactly 4.0 amps draw for calibration .

Sorry I've being doing this sort of thing all my working life so hard to stop I retirement 🤪 

[leccyflyer]

I have a number of those Lemon 7ch telemetry RX, but have not used the telemetry at all,  However I have now seen an application where the telemetry might be useful.

 

I'm refurbishing my ancient Kyosho T33 and that has an Astro 805K motor, with attached sensored ESC. Originally intended for 10 cells, it tests out quite nicely with a 3s1p 2200mah lipo. The thing is that the ancient ESC isn't lipo friendly, so the LVC onboard won;t be trying to protect the lipos from over discharge. It struck me that with the telemetry monitoring the pack voltage, in there I could set an alarm or even a periodic readback of the voltage, so that could land in plenty of time without killing the lipos.

 

The RX comes with a voltage probe - is it just a matter of connecting that to the balance plug on the battery? Does anyone use such continuous metering of pack voltage in practice?

Edited March 30 by leccyflyer

[Brian Dorricott 1]

Leccyflyer yes it's that simple to monitor pack voltage the ground is through the receiver itself , just the one wire .

[Andy Gates]

I use exactly that Leccy on my machines which are either current hungry or used as trainers.

 

Particularly with the trainers, a timer is all but useless to monitor batteries in flight as the type of flying involved has an enormous influence in battery consumption.

 

Lots of gentle circuits mean low usage and long flight times, touch and go's / aeros mean much more usage and shorter times.

 

Mine get displayed on screen but voice calls can be set up.