Do you remove your lipo from your transmitter every time?.

[Keith Miles 2]

Posted by Don Fry on 11/01/2020 07:05:34:

Keith, not complicated. Go the system setup, input a higher voltage value for the warning, higher than the brown out (6.6 v) transmitter voltage, lady tells "warning, low battery voltage".

Take heed. Land the plane.

No harm done.

Sorry to be blunt, now.

Firstly, I have noted that you have failed to answer any of the questions that I asked and are continuing to ignore or evade the points made.

Secondly, I note that you have referred to the Spektrum DX9.

So, either you are winding me up or you are a fool who misuses equipment, ignores manufacturer’s instructions and puts out irresponsible and potentially dangerous contradictory advice that might be taken in by the unwary, particularly a beginner.

I would prefer to think that it is the former but just in case it isn’t and for the benefit of those who might choose to follow your advice rather than that of the manufacturers and, indeed, the BMFA!

1. You should never allow any transmitter battery, or, indeed a Rx battery, to get anywhere near any preset low volt warning.

2. For lithium, the safe working voltage, especially for model aircraft operations, is 3.7 volts PER CELL!

3. Check the battery voltage on the MAIN SCREEN before you fly.

4. Use the TIMER on the Tx for electric models and set it LOW until you have established the discharge rate of the flight battery.

5. A preset low volt warning should NEVER be adjusted in order to use it for a purpose for which it was NOT designed.

6. ALWAYS set up the “FAILSAFE” and do NOT use it for a purpose for which it, too, was NOT designed.

Finally, failing to follow the above procedures is not just risking damage to your model but puts both yourself and other people and property at risk and would, therefore, represent an act of gross irresponsibility.

It would probably also represent a breach of the rules of many clubs, mine for sure!

Oh, and let’s not forget that new legislation and a model crashing out of bounds could also result in a visit from the local constabulary!

Edited By Keith Miles 2 on 11/01/2020 10:54:13

[Denis Watkins]

Woe Keith, try looking at the bigger picture too, as well as necessary good safe practice rules

Don writes and takes the view, like myself

From the point of view of the " flyer '

Which is to do all you can, as best you can, and Go FLY

Over the years, I have read Dons comnents

He supports safe flying, preflight checks, and concentration on best practice

Don't mistake a few words as enough to understand the man

Analyse the hell out each electrons,  but understand the joy of flying too

Edited By Denis Watkins on 11/01/2020 10:54:39

[Keith Miles 2]

Posted by Denis Watkins on 11/01/2020 10:53:48:

Woe Keith, try looking at the bigger picture too, as well as necessary good safe practice rules

Don writes and takes the view, like myself

From the point of view of the " flyer '

Which is to do all you can, as best you can, and Go FLY

Over the years, I have read Dons comnents

He supports safe flying, preflight checks, and concentration on best practice

Don't mistake a few words as enough to understand the man

Analyse the hell out each electrons, but understand the joy of flying too

Edited By Denis Watkins on 11/01/2020 10:54:39

Denis,

You may know him, others might not, including me.

You are both, presumably, experienced flyers, many others might not be.

”Taking a view” is fine. Ignoring established knowledge, written instructions, and putting out misleading or bad advice is not.

Anyone who does so, as seems to be the case, can hardly be regarded as entirely safety conscious or entirely responsible.

I can only judge on the basis of what is written and how people respond to questions, especially when they ignore or evade such questions.

I have a DX9 and stand behind my comments, including the one about his unreasonable inferred criticism of Spektrum.

If you, also, have an issue with any of the specific points that I have made to your friend or feel that they merit challenge, I would be happy for you to point out, specifically, which of those points you feel are incorrect or, specifically, where I have misunderstood what has been written.

As I said, beginners might be reading this stuff, let alone the more experienced so it is important that we all make ourselves clear.

Are you really, to give just one example, also of the “view” that running a Tx battery below 7.4 volts, let alone 6.6 volts, is entirely safe?

If so, that is not a “view” it is just plain WRONG and, with the greatest respect, you both need to begin by re-adjusting your current knowledge of lithium battery characteristics. You will find the discharge curves on the web.

Refusing to acknowledge one’s own possible, or actual, failings is also not exactly productive, or safe, either.

 

Edited By Keith Miles 2 on 11/01/2020 12:07:39

[Martin Harris - Moderator]

As a "popcorn munching non-Spektrum using bystander" watching this debate heating up, perhaps some clarification would help me. I think some people are putting LiPos in transmitters not specifically designed for them? Do Spektrum supply or advise [or warn against] using LiPo batteries?

It's been stated that the user manual warns against modifying the alarm value which I would assume to mean when using the batteries supplied with the equipment and makes perfect sense. However, I would also assume that the option to change these values is there in case a user chooses to use a different power source - otherwise why provide the facility?

Low voltage alarms on any transmitter I've owned have been primarily to alert the user to a low voltage situation occurring in flight - voltage characteristics on many cell types mean fairly rapid voltage drops can catch pilots out even when they have done pre-flight checks - and do many of us monitor our displayed voltage during a flight? I know that I've had a single cell fail on an 8 cell NiXX pack during flight and was alerted by the alarm.

Although I would hesitate to use a LiPo pack in my own transmitter for [probably unjustified] fire hazard reasons, if I did the first thing I would do would be to set the alarm at a figure which should give me a safe margin of operation and land immediately if it ever went off. My main transmitter uses a LiIon pack and has an alarm threshold set by the manufacturer which gives plenty of margin to land in any situation, although if it were to go off I, and presumably most of us, would land immediately. The display gives me an acccurate assessment of charge state percentage so I've now got out of the habit of per session charging which won't change unless I were to be intending to fly continuously for several hours in a session - which would probably make me a little unpopular on a busy club day!

Edited By Martin Harris on 11/01/2020 11:56:04

[Former Member]

[This posting has been removed]

[Keith Miles 2]

Martin,

A number of very valid points there which I do take on board and which make total sense, especially the one you make about an in-flight alert which, of course, requires added telemetry to cover the receiver as well. The latter is probably of greater use given the much greater load that is being placed upon it and the greater likelihood of transient voltage drops, unlike the Tx battery which operates on a much more stable load and uses far less current.

And, in contrast with some posts, your clarity is refreshing!

I am minded that there was a time when we had no such “helpful” features to save us from the consequences of our personal potential, or actual, failings.and when, having no fancy features or fancy chargers, we would routinely fully charge everything before flying, to ensure maximum safety.

Seems to me, however, that there is a human tendency to drop our guard or even push the limits as a direct result of advances that were designed to prevent us from doing that very thing!

The law of unexpected consequences?

I know someone who, for many years, was involved in putting together workshop manuals within the car industry and this was precisely his experience. He told me that some of the things that had to be included were almost laughable but the Company had no choice in order to cover themselves against possible claims.

For example,  I recall a reported case of a guy in the U.S. making a claim, following a crash, on the basis that he was led to believe that the cruise control allowed him to leave the driver’s seat whilst driving?

Not sure how he got on but I hope that he lost because he was, and might still be, a dangerous liability!

 

Edited By Keith Miles 2 on 11/01/2020 13:17:01

[Keith Miles 2]

May I apologise to all for any discomfort that may have been created by my previous posts but certain comments, in the manner in which they were written, may have created a misunderstanding on my part.

That said, I am unable to apologise to the individual concerned, and within this thread, until such time as he has clarified the full circumstances of his reported crash and, thereby, corrected any such misunderstanding.

It is, therefore, for him to now respond directly to points raised or I, for one, will be forced to draw my own conclusions and move on.

Sorry, but I felt that this needed to be said.

[Don Fry]

Keith. I will have one more go.

For whatever reason, Spectrum shipped their DX9 with a battery warning set at 6.4 volts for the filtted Li-ion battery. Page five of the Manuel, Battery alarm, and so it was in practice, when examined after crash.

There is a caution box below this statement, which says, don't change the lower voltage limit from this setting, Doing so could over-discharge the battery.

Fair enough. We are all familiar with the care of Li-xx batteries. Don't run them BELOW voltage limits.

Now I have tested the transmitters, DX9 type, note plural. They stop working, self switch off, at 6.6 volts. This is the computer shutting down not a battery protection cuircuit. Brown out in our language.

Now I refer to page 21 of the manual, System Settings, Battery Alarm. Paragraph 1 refers to the ability to change the voltage, when changing battery types. Last sentence says to quote" The alarm activates when the battery reaches the low voltage limit."

Well it does not. It is set to 6.4 volts, as shipped. At 6.6 volts the computer stops. And the transmitter switches off. And the plane crashes.

Cure is, go to paragraph 2, same section, where it tells us how to change the alarm voltage. Change the voltage to a value above 6.6 volts. This allows the low voltage alarm to tell the user the battery is running low. It has to be set above 6.6 volts, or it won't be heard, as the transmitter has already shut off.

Here endeth the lesson.

Now, the diatribe you launched Keith is forgotten, in the past, a small disagreement between fliers. There is enough to make this game difficult. I will accept you got hold of the wrong end of the stick. End of conversation. I have in the past made a fool of myself on this site, and have had the forbearance of others. Can we draw a line under this?

Edited By Don Fry on 11/01/2020 14:49:46

[Don Fry]

Keith. I an retired. That means I am not under the beck and call of a boss to explain and cajole, at his whim and pleasure. I don't intend to appoint you as my boss. I don't want an apology, as I have said.

[Keith Miles 2]

Posted by Don Fry on 11/01/2020 16:10:21:

Keith. I an retired. That means I am not under the beck and call of a boss to explain and cajole, at his whim and pleasure. I don't intend to appoint you as my boss. I don't want an apology, as I have said.

I too, am retired, having spent over 50 years as an electrician.

I am neither, bossing or cajoling, merely trying to set the record straight for those who might be taken in by what you post, and when politely and respectfully challenged or questioned in order to get some clarification, refuse to respond in an appropriate fashion and, thereby, ensuring that another “myth” will circulate with similar consequences.

People who try to cover their own mistakes by trying to point the finger elsewhere, as I must now assume is the case here, are regarded, in my view as dishonest, at best, and arrogant at worst.

If, indeed, you are one of those, thankfully relatively few people, who do not use their equipment in accordance with the manufacturer’s instructions or within accepted practice then you are also a danger to not only yourself but others as well.

Anyway, back to the detail and for those interested, on the DX9, at least, the low volt cut-off is ONLY there to protect the battery from over-discharge and possible additional damage to the Tx. It is NOT there to protect the user from failing to follow correct normal procedures or failing to take notice of primary information also provided e.g. that on the main screen.

The Spektrum DX9 manual is available on line. See pages 2 and 5 regarding general care of batteries and the low volt cut-off.

The DX9 also has a voice alert for throttle position when switching on.

Perhaps, as this case might demonstrate, there might be an argument for an audible warning for voltage as well and I would suggest, perhaps, 7.2 volts for a 2S lithium.

This would be in addition to, not a replacement for, the existing preset low volt cut-off.

You can bet your life, though, that somebody would misuse that as well.

[Bob Cotsford]

In all my time flying RC, from single channel superhet up to the modern day, I've never before come across a battery meter or warning that is set to go off after the tx has lost connection or stopped working. It sounds a bit silly really when what you want is a warning that the battery level is dropping to the point where you will lose control whether through your own negligence or a battery fault. Who cares if the battery is damaged from over discharge after you've just lost n hundreds of pounds worth of model? Apparently only Spektrum.

Thank god the days of having to monitor your battery voltage as you fly are long gone, eh?

[Pete B]

Getting a tad heated here so, as there is enough info now for folk to make their own judgement, I'll do as Don suggested earlier and draw a line under this thread....

Pete