Tearing what is left of my hair out

[GrumpyGnome]

Evening all

Am now copiously swearing and tearing my hair out.... have searched YouTube and Googled for a number of hours but cannot resolve my conundrum, which is this.....

I have a timer set up on my WotsWot foamy on my Taranis. But, I use a number of batteries of varying capacity and age so sometimes land electron-rich and sometimes on the very limit. So, I thought I'd make use of telemetery, and bought a MLVSS from T9, figuring that I could buy a few and shift them from plane to plane.

Righty-ho, off we go. First off, let's find the little lead that came with the RX6R Access receiver. Got it. Plug it into the white smart port socket on top of the rx. Plug the 'servo type' plug into the MLVSS, making sure polarity is right. Turn on Tx. Plug in LiPo; attach balance lead to MLVSS, making sure that black lead is in Ground pin. Go to Telemetery screen on Tx and select 'Discover new sensors' - I then see:

• A2 showing around 7v
• RSSI showing around 100 db
• RxBt showing around 6v.

But, nothing relating to the Lipo pack. Spent an hour trying to move leads, rebinding, rediscovering sensors, deleting sensors etc. but no success. Hmmmm.

Let's try an RX6R that does not say ACCESS on it. Works like a dream! Hmmmm, Let's try an X8R using the servo cable-like lead that came with the MLVSS. That works like a dream too. Hmmmm.

Can't understand this and the only difference I can see between the RX6R ACCESS and RX6R non-ACCESS is that the LED on the ACCESS rx is solid blue whilst on the non-ACCESS RX6R and the X8R it is solid green.... (I rebound the ACCESS version a number of times and it is always solid blue but has a rock-solid RF link..)

Hoping someone can help me - I strongly suspect user error......

TIA

Very GG

[Bob Cotsford]

Did you use the same lead for both RX6Rs? The Access receivers I've updated so far seem to be working ok but I don't have an RX6R. You could flash the Access one to ACCST and try it again to see if it's the firmware or hardware that's at fault.

Is it the same pin assignment on both receivers? I've just tried connecting an MLVSS to an RX4R running on Access and it picks up the Cels ID when I discover sensors but one thing I noticed was that it has the usual green light indicating a good bind. This rx uses a 6 pin connector for Sport/Sbus etc where other receivers use 4 or 5 pins.

[Bob Cotsford]

As Steve says a current sensor is better for monitoring battery capacity, voltage sensors are better at highlighting bad cells! If you don't have space for a current sensor then the voltage is better than nothing but voltage is affected too much by instantaneous current draw to be a reliable guide to capacity available in my view!

[GrumpyGnome]

Hi Steve J

The aim is for a voice warning when the lowest cell hits, for example, 3.8 volts..... nor perfect but probably ok for my needs.

Hi Bob, wonder why my ACCESS RX6R has a solid blue LED..... will investigate that.

GGG

Edited By GrumpyGnome on 05/01/2021 18:40:47

[Doug Campbell]

Surely your esc will cut the motor when the battery voltage is low. Do a quick dead stick landing, jobs a good un

Edited By Doug Campbell on 05/01/2021 18:47:16

[Andy48]

Posted by Doug Campbell on 05/01/2021 18:43:43:

Surely your esc will cut the motor when the battery voltage is low. Do a quick dead stick landing, jobs a good un

Edited By Doug Campbell on 05/01/2021 18:47:16

Yes it will, or simply reduce power if you have it set that way, but rely on a dead stick landing every time, no way! Also by the time an ESC cuts out, the battery will have been drained far too much to ensure a reasonable lifespan for the battery.

A combination of a voltage sensor and current sensor is far more sophisticated. The voltage sensor measures the voltage of each cell in real time, and is great for indicating when the first cell in a battery is starting to fail. The current sensor accurately measures the consumption of the battery giving warnings when the battery is starting to reach the optimum discharge level. Of course, warnings can be verbal so no need to look down at the screen.

The consumption is really useful when the IC guys do their frequent dead stick landings, a quick flick of a switch and I know exactly how much battery I have left, then I can fly round with confidence while the IC guy goes and collects the various parts of his model scattered along the landing site.

[john stones 1 - Moderator]

Posted by Andy48 on 05/01/2021 22:12:46:

Posted by Doug Campbell on 05/01/2021 18:43:43:

Surely your esc will cut the motor when the battery voltage is low. Do a quick dead stick landing, jobs a good un

Edited By Doug Campbell on 05/01/2021 18:47:16

Yes it will, or simply reduce power if you have it set that way, but rely on a dead stick landing every time, no way! Also by the time an ESC cuts out, the battery will have been drained far too much to ensure a reasonable lifespan for the battery.

A combination of a voltage sensor and current sensor is far more sophisticated. The voltage sensor measures the voltage of each cell in real time, and is great for indicating when the first cell in a battery is starting to fail. The current sensor accurately measures the consumption of the battery giving warnings when the battery is starting to reach the optimum discharge level. Of course, warnings can be verbal so no need to look down at the screen.

The consumption is really useful when the IC guys do their frequent dead stick landings, a quick flick of a switch and I know exactly how much battery I have left, then I can fly round with confidence while the IC guy goes and collects the various parts of his model scattered along the landing site.

Go on I'll have a nibble, a deadstick is no biggie, glider/slope lads do it all the time, nor is running an I.C engine.

Naughty step for me now, off topic.

[Bob Cotsford]

Deadsticks with bipes or tripes ain't so clever John . Nor with light loaded vintage types if you're downwind

But in general you are right, deadsticks shouldn't be a problem generally and I suspect Andy has his tongue stuck firmly in his cheek. Then again, how many glow flyers would love to have a fuel gauge if they could? With leccy power it's pretty commonplace!

[john stones 1 - Moderator]

Just a bit of fun Bob, I have a fuel gauge on mine, when the noise stops it's empty.

[Bob Cotsford]

I used to have the same one John, but now I've been converted to the one true faith, Praise Be to the Almighty Electron

[Mike Blandford]

The manual says the blue LED indicates HS mode (9mS servo pulse period).
Are you running ACCESS protocol or ACCST protocol to the ACCESS labelled receiver? If ACCESS, go into the receiver options and make sure that "FPort" is turned off, otherwise the Rx is using FPort instead of SPort.
If you have flashed ACCST firmware, maybe the Rx is still using FPort.

If you are using ACCESS firmware, then you may need to use the receiver options to change from HS mode (to FS mode) to get the servo pulse period to 18mS for analog servos.

Mike

[GrumpyGnome]

Soooooo.....

Have retried many times to get rid of the blue LED and have a nice shiny green one. To no avail.

But..... telemetary is working as sensor A2 now reads the LiPo pack. I have added a logical switch to activate below a given voltage, and added a voice alert (my wife not the ubiquitous Amber), and added a 'duration' so the alert is only active if the voltage is low for 2 seconds or more. Not ideal, as I cannot check each individual cell voltage, but gets me closer to what I want.

The Rx is currently set as ACCESS, and FPort is unchecked. I have followed the manual and depressed the f/s button for 5 or more seconds but no effect.

If I can be bothered, I may flash the Rx firmware and/or set up a new model from scratch so it works like my non-ACCESS RX6R and my 8XR.....

Thanks for the help,

GG

[Andy48]

Posted by john stones 1 Moderator on 05/01/2021 22:28:52:

Go on I'll have a nibble, a deadstick is no biggie, glider/slope lads do it all the time, nor is running an I.C engine.

Naughty step for me now, off topic.

There's a world of difference between a planned deadstick and an unplanned one. If, as I do, I always put a more powerful electric setup than actually needed, and generally fly on half throttle or less, it can be difficult to see or feel when the ESC reduces power, and as I said above by then I've probably already used more of the battery capacity than is good for its long term health.

We've all done deadstick landings for the "A" test of course, and to be fair I've seen lots of damage caused by unplanned IC deadstick landings on our field. Unplanned ones always come at the most inopportune time as decreed by sod's law. Personally I haven't had an unplanned deadstick for many years now, and hope to keep it that way. After I've spent many weeks or months building my latest pride and joy, I'm happy to be a wimp and rely on technology to help keep it in one piece.

... hope there are comfy cushions on the naughty step.

[Mike Blandford]

The manuals I'm reading don't mention pressing the FS button to change mode. If ACCST it says fit a link during binding, in ACCESS mode it says use the receiver option on the Tx.

Mike

[GrumpyGnome]

Hi Mike

My bad.... the long key depress sets ch16 to telemetery or 'normal'. The only way of changing rx modes is via the Options menu of the receiver..... that ootion does not exist so is possibly available on OpenTx versions later than I am using (or I need to flash the rx). In any case, I can do exactly what I want on my other planes, and this one is close enough for now

Still loving this OpenTx malarkey!

Cheers,

GG

Edited By GrumpyGnome on 06/01/2021 15:15:49

[Bob Cotsford]

GG, can you check that the sensor is definitely connected to pins 1,2 and 3 and not 1, 2 and 4? Pin 3 is Sport, 4 is A2 so I'm a bit surprised that you're getting an accurate LiPo voltage through A2 when it's connected to Sport!

[Dave S.]

I only recently acquired an FrSky open tx system, and set it up in an electric Wot 4. I was advised to download an update for the (Archer) Rx, which I di but then lost all telemetry. Asking around, I was told that there was a known fault in the update in that the sensor input was changed from S port to F port, even though it still showed as S port on the Tx. I changed it to F port and the back to S port since when it has worked perfectly (though only on the ground, circumstance and weather have kept me away from the flying field recently).

[Bob Cotsford]

Posted by Dave S. on 06/01/2021 16:37:36:

I only recently acquired an FrSky open tx system, and set it up in an electric Wot 4. I was advised to download an update for the (Archer) Rx, which I di but then lost all telemetry. Asking around, I was told that there was a known fault in the update in that the sensor input was changed from S port to F port, even though it still showed as S port on the Tx. I changed it to F port and the back to S port since when it has worked perfectly (though only on the ground, circumstance and weather have kept me away from the flying field recently).

That's probably buried deep in an RCGroups thread! Well worth remembering that one!

[Doug Campbell]

I spent many years flying 2 channel rudder/elevator models so every flight was dead stick. You soon get used to it and get better at positional planning. I still dead stick my multi models out of habit, it is what I’m used to.

[GrumpyGnome]

Hi Bob

Just spent 20 mins trying to describe this in more detail, and failed miserably! In the morning, I will take some pictures - far better than 1000 words.....

Cheers

GG

[GrumpyGnome]

I understand all the points re dead-stick landings, and having spent 15 years or so flying single channel powered planes, and slope soarers, have no problem achieving it. But...... when flying with others, I'd like to be in control of when I land......... especially when one of the joys of electric flight is avoiding a 'dead stick' situation...

GG

[Malcolm Fisher]

My introduction to R/C was with a single channel Super regen Mc Gregor radio so I could only fly if no one else was around. I used a glider - modified KK Chief a a slope soarer. Later graduated to two channel gear and still with slopers. When I started with power, I couldn't land with power on so always flew the tank dry and landed dead stick as that was what I was used to doing. Never been worried about dead stick landings ever since but did eventually learn to land with the engine still running.

Malcolm

[GrumpyGnome]

Sorry, meant to say "...ESPECIALLY when flying with others..."

GG

[Peter Christy]

I, too, started flying with single channel and had to land dead-stick. Even when I progressed on to multi-channel, I decided to forego throttle control in favour of elevators. Flew like that for years, so dead-stick holds no fears for me.

SteveJ: Every ESC in my possession came already programmed to cut out when the safe minimum volts/cell is reached. Admittedly its is possible to change this, but I doubt if many people do. All modern ESCs do a cell count on initialisation for this very reason, so I'm not sure why you think flying to the cut-out level will damage the LiPos.

The amount of power drawn by the radio and servos is negligible compared to the motor. As soon as the motor cuts, the LiPo will effectively be "off-load", allowing the voltage to rise slightly above the minimum level - which was almost certainly set conservatively high anyway. This will certainly be enough to land anything but perhaps a thermal soarer quite safely.

--

Pete

[Andy48]

Posted by Peter Christy on 07/01/2021 09:59:04:

SteveJ: Every ESC in my possession came already programmed to cut out when the safe minimum volts/cell is reached. Admittedly its is possible to change this, but I doubt if many people do. All modern ESCs do a cell count on initialisation for this very reason, so I'm not sure why you think flying to the cut-out level will damage the LiPos.

There are three points here. Firstly there is no threshold as such to determine a minimum safe level of battery discharge. Its a sliding scale. Personally I prefer to land well before the batteries get down to their minimum, and that seems to pay in terms of battery life.

Secondly, the ESC measures the whole battery voltage, not the individual cells. It may well be that one cell that is beginning to show its age will drop voltage under load more than the rest. This would mean that this cell could well be stressed even further.

Finally, flying from a normal flying field I always like to have a usable reserve of battery power. I find it not uncommon to plan my landing and find another flyer is having difficulty and needing the field clear for their landing.