Typhoon H Pro Becomes Unstable at 14.3V

[Steveromo19]

Hello all,

I just bought my Typhoon H Pro kit a little under a month ago from best buy. First and foremost i LOVE this drone. My first drone ever and I no doubt made the right choice after many months of research. It pains me to post about this not even a month after purchase but I need help with this issue.

Recently in the last couple weeks I have noticed when the Typhoon H hits 14.3v and the first battery warning appears my drone becomes very unstable and erratic. If the control are totally left alone at the time of first battery warning the H will start "toilet bowling" as I have seen it referred to on here. It will also rapidly raise in altitude as well as drop in swift random movements. It makes it nearly impossible to land the craft without incident. Prior to this issue I had not updated any firmware on the ST16 nor the bird itself. I left it as it came firmware and all. I have seen many people on these forums post about this issue but usually to no resolve as far as I know. I have also seen that people are experiencing these issues even earlier at 14.7v and 14.5v.

I started noticing a few days ago that the H would start slightly drifting after a maneuver for a few feet before it would catch itself and stay in place well before any battery warnings. I uploaded telemetry of several flights to exmaps. I have noticed when the battery warning hits I get a compass calibration error and that is when the erratic behavior begins. I also have noticed the telemetry indicates the drone is never recorded landing at the same altitude it took off from. I take off and land on my driveway and my driveway is level. I flew last night and the telemetry thinks I landed 5.8m (20ft.) above where I took off from. I am starting to think the H either loses GPS at the point of low battery altogether or is completely disoriented.

I finally contacted Yuneec. Customer support told me to update firmware on the both the controller and H, recalibrate the compass and accelerometer and try again. Last night I updated everything, recalibrated the compass north, and also recalibrated the accelerometer on a flat and level surface (my kitchen floor - I even used a level to verify). I took the H out - flew around until the battery was around 14.5v. I then hovered it in front of me until the first battery warning. As soon as the warning hit the H became unstable as usual and started toilet bowling. Fortunately is had just snowed here and I was able to not so gracefully land without consequence on the extra cusion.

I have emailed Yuneec and explained to them the problem still persists - I have read numerous posts on the forums of people who have had this problem, sent the bird to Yuneec (paying shipping costs) only to wait 3 months for it to come back and still experience the same problem. I do not want to fall victim to the same situation.

So A: I am looking to see if anyone has actually been able to trace this problem to it's roots indefinitely -because customer support has "never heard of this happening before" (yeah right) which leaves me pretty skeptical about them performing a successful fix or B: returning to Best Buy for a return before my month is up and can no longer return. I understand Yuneec does not do refunds. Really love this drone, it's features and styling go a long way for me and would most definitely like to keep it but I do expect a level of reliability. I do not use it for commercial work, filming or any sort of photography. I just simply like flying it around for fun. I need it to take off, fly and land. At this point I am missing the latter.

Any help is appreciated thank you.

-Steve

 

[PatR]

Not a solution but a possible explanation might be a motor or speed control that is pulling too many amps under load. If such was the case a battery at a reduced voltage level may not be able to supply the load demanded by the entire system. Add to that the possibility of using batteries that have high internal resistance from whatever cause and you have another possible cause.

 

[Steveromo19]

Not a solution but a possible explanation might be a motor or speed control that is pulling too many amps under load. If such was the case a battery at a reduced voltage level may not be able to supply the load demanded by the entire system. Add to that the possibility of using batteries that have high internal resistance from whatever cause and you have another possible cause.

PatR,

Thank you for your response. While I stated that there were many people echoing the same situation as myself, I also failed to mention that there were many who posted they are able to take it down to 14.3v without issue. If there were power restrictions in any way wouldn't everyone be experiencing these issues? Or could it be my batteries are not performing the same anymore?

 

[Steve Carr]

How many batteries do you have and do you get the same result with each?
My first suggestion is to land before you get the battery that low. I have never waited for the voltage to get below 14.7. That is way to close to the margin of failure. When you know the limits of your aircraft it's a good idea to stay within those limits. If you keep pushing them bad things are more likely forthcoming.

 

[Steveromo19]

Steve Carr,

Thank you very much for your feedback, I have 4 batteries - all Yuneec brand. Nothing aftermarket. I use the stock charger on each.

In the short time I've owned the aircraft I have read many opinions on batteries and voltages to land at. While I understand the concept behind it and the workings of a Lipo battery, I also would like to abide by the manual provided with the drone that says to start the landing process at 14.3v or the first battery warning. Landing at 14.7v would really limit my flight time and I would assume Yuneec intended for landing at the first battery warning considering the literature they provide.

People are flying through the first battery warning no problem and some even after the 2nd (of course immediately landing).

As far as I know I am getting the same result with each battery as I go one after the other with the same problem. I have been landing at 14.6v lately to avoid the problem altogether, but I don't think I should have to settle when this drone should be fully capable of going to the manufacturers recommended first battery warning. Especially for an $1800 product.

 

[PatR]

I understand your sentiment, but Yuneec documentation also states flight time of "up to" X minutes. Nowhere does it guarantee a flight time duration. I land at 14.8v by choice and am satisfied with the flight duration provided. I do not endeavor to obtain every possible moment of flight time from a battery with any of my multirotors, from Yuneec or anyone else.

 

[ArnhemAnt]

In the short time I've owned the aircraft I have read many opinions on batteries and voltages to land at. While I understand the concept behind it and the workings of a Lipo battery, I also would like to abide by the manual provided with the drone that says to start the landing process at 14.3v or the first battery warning. Landing at 14.7v would really limit my flight time and I would assume Yuneec intended for landing at the first battery warning considering the literature they provide.

Steve, I think this may be the cause of your problem, particularly if you are using the stock charger. A battery taken down to 14.3v leaves the individual cells at around 3.5v. If you are then taking them down further than that before you actually land and power off, then I am presuming that you may have an even lower voltage reading. Given this information, if you are then leaving these batteries at that level prior to charging again, then this can have an effect on the life and condition of the batteries.
When not using a LiPo, it is good practice to leave the batteries at 'storage' which is around 3.8v per cell (15.2v total). The stock charger does not have this ability.

Like PatR has mentioned above, I make a point of landing at 14.8v (telemetry readout on the ST16), which then gives me a 'cold' reading of 3.8v per cell. This way your battery is already at a suitable voltage for storage. In my opinion, waiting for the low battery warnings (regardless of how many there are) is leaving things far too late. I think this feature was included by Yuneec as a 'warning' and not a recommendation.
I'd be interested to know what your individual cell readings and the IR on each battery is - I think this is why you are experiencing the issues you have stated above.

 

[NorWiscPilot]

Steveromo19 and all,

Maybe I can offer some insight as I am currently working with Yuneec support for this very issue. I was going to wait until I have some concrete details as to a remedy, but this looks like as good a time as any.

Details: I have flown my H from the exact same location for every flight so far, that being a frozen lake in northern Wisconsin, right out my door. This past Wednesday, with the sun bright, not a cloud in the sky and calm winds, I decided to test a neutral density filter vs the stock uv filter. Just something to satisfy my curiosity plus an excuse to take a break and fly!

First test flight was uneventful - up to 30 feet, spin the camera, take a still, and back down.

Second flight, after putting on an 8 stop ND filter - up to 30 feet, spin camera, and down. But... as I brought it down to land, at about 4 feet, I noticed a drift. I let it go and saw the characteristic "circular flight" as we have seen described here.

After several attempts to get to my landing spot on the ice, I finally had to just set it down. When I could tell the motors were not going down to idle, I kept the throttle stick down while reaching across to the motor start/stop button, killing the motors. During this time, the H did try to buck a few times, only one side lifting off the snow.

Being a service tech and in customer support for 37 years, I just had to know if this was a one time event or a solid "failure". After checking all the switches and settings in case I had inadvertently hit something (all good - still in angle, GPS on, turtle, et al) I started the motors and observed a smooth idle.

Carefully throttling up, I got the H up to about 4 feet when it started circling again. I tried to bring it down right away, and managed to but, the motors were even more determined this time. I could not get to the kill switch before the H started bucking even more violently. It flipped away from me and over, stopping the motors itself. The one benefit of this time of year - a light dusting of a couple inches of snow on top of flat ice makes for little damage to the air frame!

After documenting everything in my flight log, I waited until the next day (yesterday March 16) to call Yuneec customer support. The rep who called back has already been mentioned in these pages, in a very good light (CCRider) so I already had a good feeling!

After describing my incident, I was told this: the GPS issues have been re-engineered and fixed (hardware-wise) as well as firmware. Today's issues are likely due to battery voltages, similar to Steveromo19's description. This was after mentioning that my voltages were between 14.6 and 14.9 at the end of the second test flight, albeit short as it was. To validate, it was suggested that I try some test flights with a fully charged battery to see if I could reproduce the "circling flight".

Here's my engineering background kicking in: I was skeptical that this is a voltage issue, at least not completely. Why not? In the 40+ flights so far, I have managed to hit the first low voltage warning a few times, but always within close proximity. I see 15.0v and I am heading back if I am any distance away. That does not mean I land right away. I often test the system, keeping the bird close but honing the fine motor skills (sorry... couldn't resist). In other words, every so often I would see 14.4, 14.3, and a few test times actually saw the second low voltage warning. All uneventful as far as control is concerned.

With two fully charged batteries, I went out for testing. I was as attentive as I could be as to "conditions" noting every nuance. Here are the results for my tests:

Flight 1:

Upon power up and first satellite acquisitions - altitude reported as 0ft. However, as more satellites were acquired, the altitude increased to 2ft or more. Standing in my usual spot, the distance between the ST16 and the H was being reported as 40+ ft. In actuality, I was maybe 20 feet away. (Not to worry, I fly angle mode only, hence my pre and post flight checks as mentioned above.)

After waiting several minutes, I eased up the throttle and lifted off to about 6 ft. (This is critical). The H, despite some light gusting of the wind, held pretty steady. I did not touch the controls at all until the voltage dropped to 14.3v and the first low battery warning flashed. Circling flight did NOT occur… yet.

It should be noted, hence the earlier 6ft altitude comment - while the horizontal positioning stayed pretty stable (I mean - it stayed within 4 or 5 feet of its lift-off point for close to 15 minutes) - it did not hold a steady altitude. While the altimeter was still reading 6.4ft or so, the H had actually climbed to between 10 and 13 feet. Not all at once, but more like a little bounce during a correction for wind, or a subtle elevation change just because it felt like it.

As I brought the H down to land, it started the circling flight when it hit about 4 ft (visual, not altimeter). Anticipating this, I made sure I knew exactly how to turn off GPS, before I even thought of starting the flight, and it came in handy. I turned off GPS, the circling stopped, and I was able to make an uneventful landing. Noting the altimeter, it now read -4ft. My H thought she was under the ice!

Now comes the reason for the second battery - fully charged - we repeat the same test with a bit of a change - instead of waiting for low voltage, after take-off to about 10 ft, I brought the H down to 6ft. Stable. Then down to 4ft. Anyone reading this likely knows what happened next: the H started circling again, on full battery!

Back up to 6 ft, circling stopped. Down to 4ft, circling started again.

Just to eliminate the slight possibility of the shoreline trees infringing on the GPS like they had never before, I pushed the H out further over the lake and did the same tests with the same results.

Brought the bird home to roost, leaving the GPS on - as long as I came down steady and landed firm but soft enough not to break anything, I did not notice any drift. It was only if I allowed the H to hover under 4ft or so, did I notice drift and then circling.

I sent all my detailed notes, along with the telemetry files, to Yuneec earlier this morning. I hope to hear back in 2-3 days with their analysis and will report back.

In closing, I have the following observations:

About this forum and Yuneec -

1. This forum is a wealth of information, shared by very caring and passionate people. Protect it we must!
2. Yuneec Customer Support, as described here at least by the majority of posts I have read, is top notch. (CCRider's exploits, along with ChadCloses, are a couple recent testimonials.)

About "paying attention to details":

Personally, I take the U.S./FAA privilege seriously, and thus try to be as complete as possible with my flight logs, not just in case, but for future reference and learning. After this incident, I remember making notes about "drift during landing" specifically after applying the latest firmware update (Feb, 2017). I didn't notice the "much better" landings reported by other members of this forum. I had been noticing increasing drifting, but more side to side than anything, and chalked it up to ground effect. Maybe I now have more detail as to what might have been a precursor to a growing problem.

Apologies if anyone thinks this post is too long winded. I am hoping the exact details of my experience might help someone else decipher their own issues, especially when someone (the OP) explicitly asked. I was going to wait until I had my resolution details before posting, but Steveromo19 asked and I could not ignore, considering the similarity of issues.

Parting shot: If you do not know already, make sure part of your pre-flight checklist is to reacquaint yourself with exactly how to disable GPS, and to be able to do it quickly - if nothing else, gain altitude to give yourself time!

Thanks!

Jeff

P.S. Per Typhoon Charlie's point: So far, I have always calibrated the compass with the camera attached.

 

[Steveromo19]

Steve, I think this may be the cause of your problem, particularly if you are using the stock charger. A battery taken down to 14.3v leaves the individual cells at around 3.5v. If you are then taking them down further than that before you actually land and power off, then I am presuming that you may have an even lower voltage reading. Given this information, if you are then leaving these batteries at that level prior to charging again, then this can have an effect on the life and condition of the batteries.
When not using a LiPo, it is good practice to leave the batteries at 'storage' which is around 3.8v per cell (15.2v total). The stock charger does not have this ability.

Like PatR has mentioned above, I make a point of landing at 14.8v (telemetry readout on the ST16), which then gives me a 'cold' reading of 3.8v per cell. This way your battery is already at a suitable voltage for storage. In my opinion, waiting for the low battery warnings (regardless of how many there are) is leaving things far too late. I think this feature was included by Yuneec as a 'warning' and not a recommendation.
I'd be interested to know what your individual cell readings and the IR on each battery is - I think this is why you are experiencing the issues you have stated above.

Thank you Arnhem - I usually do the opposite. I fully charge the batteries after use for the next flight - which is usually a day or two later. I have attached a picture of my exmaps view for you. If I landed during my flight at 14.7V I would have a 10 minute flight time - almost half of what I could achieve going to 14.3v.

 

[m5zealot]

How many batteries do you have and do you get the same result with each?
My first suggestion is to land before you get the battery that low. I have never waited for the voltage to get below 14.7. That is way to close to the margin of failure. When you know the limits of your aircraft it's a good idea to stay within those limits. If you keep pushing them bad things are more likely forthcoming.

Totally agree! I have 4 batteries and will be getting another 2. I land way before I get the 1st warning. I usually set my cell phone warning alarm at 15-20 minutes and land right away. No use taking risk of a falling H. Having lots of batteries tend to give you confidence to not fly at dangerous low battery levels! I understand batteries are not cheap but, crashing and destroying the H or worse injuring people/damaging property is way worse.

 

[Typhoon Charlie]

Are you calibrating compass with camera on or off. I have some observations. I have always calibrated with camera on and never had any toilet bowl issues. After reading that you should take the camera off I calibrated both mine with it off. You guest it, toilet bowl and erratic flight behavior after being on the air for some time after battery got low. Calibrated with camera on and all is good. I believe by calibrating with camera off the installing the camera, you are introducing the magnetic field of the camera ( 3 motor with magnets) along with the WiFi RF field which makes the compass calibration useless. Toilet bowling or circling is always a compass issue, by turning GPS off you are no longer relying on the compass you are on manual mode. As the voltage decreases the amperage goes up increasing magnetic field. I need to test this many more times to affirm that this is in fact an issue. In all the years of building with APM flight controller I learned to calibrate with the format the aircraft was going to fly. If I added or removed some piece of hardware, then calibration was always done.

 

[Rayray]

Steveromo19,
You have so many doubts that I do not want to tell you not to return your craft to Best Buy with your return window closing.

I do not agree with some of your tests and conclusions, but I do agree that the craft should fly as well at 14.3 volts under load, especially in Turtle mode, as at any other higher voltage. However, If you have flown your batteries below 14 volts under load, they may be damaged.

Whatever you decide, I feel for you and I understand your fears. I wish you good luck.
BTW, do not email Yuneec, you must call them.

 

[Steveromo19]

Are you calibrating compass with camera on or off. I have some observations. I have always calibrated with camera on and never had any toilet bowl issues. After reading that you should take the camera off I calibrated both mine with it off. You guest it, toilet bowl and erratic flight behavior after being on the air for some time after battery got low. Calibrated with camera on and all is good. I believe by calibrating with camera off the installing the camera, you are introducing the magnetic field of the camera ( 3 motor with magnets) along with the WiFi RF field which makes the compass calibration useless. Toilet bowling or circling is always a compass issue, by turning GPS off you are no longer relying on the compass you are on manual mode. As the voltage decreases the amperage goes up increasing magnetic field. I need to test this many more times to affirm that this is in fact an issue. In all the years of building with APM flight controller I learned to calibrate with the format the aircraft was going to fly. If I added or removed some piece of hardware, then calibration was always done.

Typhoon Charlie,

I am recalibration with the camera on - never have taken it off. Do you think the wifi from the wireless router in my house would possibly mess with the calibration?

 

[Steveromo19]

Ray ray,

Thank you for your input and advice. I simply just want the peace of mind if I were in fact to hit the first low voltage warning that I can maintain co trip of my aircraft. When it is windy and sometimes the craft is moving aggressive it can drop quite fast even if you are timing a landing at 14.6v. Also, out of curiosity which conclusions and test do you not agree with? I am extremely open to all ideas as I said before - I love this drone!! I just want to sort this issue out.

Norwiscpilot,

Thank you for your story and experience. This is exactly the feedback I was looking for. Someone who is knowledgeable and has possibly experienced and investigated this type of behavior and the information you found. I hope that we can find the solution to what seems to be a very similar problem. My erratic flight unfortunately is not contingent on altitude. I will try to turn off gps to make a quick save in the meantime.

 

[Rubik]

Typhoon Charlie,

I am recalibration with the camera on - never have taken it off. Do you think the wifi from the wireless router in my house would possibly mess with the calibration?

I have had no flight issues after calibrating with the camera removed. However, I always calibrate in the middle of nowhere to ensure no interference from nearby metal. Can you do your compass calibration in an empty field within a few miles of your home?
WiFi range from your home router is pretty limited. Just how close to the router are you when you fly? I hope someone more knowledgeable than I will tell us IF in-home WiFi can interfere with drone flight control. I suspect WiFi channels are sufficiently separated that this would not be in issue.

 

[gwhuntoon]

Just some info about Lipos. This was a little hard for me to get my head around at first but here it goes -

Here's the easy part, for the Yuneec 4S battery, 16.8v is full or 100% and 0v is 0% or empty. (This is just for illustration, never discharge below the low voltage of a Lipo)

The harder part is understanding that the operating range of a Lipo cell/battery is the top 20% of the overall battery capacity, so in the case of a Yuneec 4S battery, 16.8v is 100% or full and 13.4v is actually 0% or empty. 14.3v, when the low voltage warning kicks in is actual 25% remaining in the Lipo operating range.

Nominal voltage for the Yuneec 4S battery is 14.8v or 40% charge in the Lipo operating range.

Personally I land long before the low voltage warning. I just don't want to over stress the cells. Also, I think the Yuneec Lipos are rated for 1000 complete charge discharge cycles in their useful life with a full cycle being from 16.8v to 13.4v. If you land before low voltage cut off you will have only used a fraction of a cycle and could potentially net more than 1000 complete cycles, assuming you take it easy with charging discharging, and storage. I also think 1000 cycles is probably optimistic, realistically you may only get half that.

I've had issues with other batteries where one of the cells in the battery gets weak and out of balance with the other cells. When this happens you will hit the low voltage cut off much quicker. Additionally the weak cell puts additional load stress on the remaining good cells so the drop off is less linear. What I'm hearing above sounds like it could be a bad battery.

 

[glider]

If the cells are differing by .5v after landing, the battery is near death. One of the first things I did was modify the charger to use the iCharger to test the cells.

 

[Steveromo19]

Just some info about Lipos. This was a little hard for me to get my head around at first but here it goes -

Here's the easy part, for the Yuneec 4S battery, 16.8v is full or 100% and 0v is 0% or empty. (This is just for illustration, never discharge below the low voltage of a Lipo)

The harder part is understanding that the operating range of a Lipo cell/battery is the top 20% of the overall battery capacity, so in the case of a Yuneec 4S battery, 16.8v is 100% or full and 13.4v is actually 0% or empty. 14.3v, when the low voltage warning kicks in is actual 25% remaining in the Lipo operating range.

Nominal voltage for the Yuneec 4S battery is 14.8v or 40% charge in the Lipo operating range.

Personally I land long before the low voltage warning. I just don't want to over stress the cells. Also, I think the Yuneec Lipos are rated for 1000 complete charge discharge cycles in their useful life with a full cycle being from 16.8v to 13.4v. If you land before low voltage cut off you will have only used a fraction of a cycle and could potentially net more than 1000 complete cycles, assuming you take it easy with charging discharging, and storage. I also think 1000 cycles is probably optimistic, realistically you may only get half that.

I've had issues with other batteries where one of the cells in the battery gets weak and out of balance with the other cells. When this happens you will hit the low voltage cut off much quicker. Additionally the weak cell puts additional load stress on the remaining good cells so the drop off is less linear. What I'm hearing above sounds like it could be a bad battery.

gwhuntoon,

It is happening with every one of my batteries. Guess I am at a loss here.

 

[ArnhemAnt]

I have had no flight issues after calibrating with the camera removed. However, I always calibrate in the middle of nowhere to ensure no interference from nearby metal.

That's exactly what I do, and, to date, I have never had an issue with my gear.

 

[Steve Carr]

@Steveromo19
I'm getting the feeling you will never be satisfied with this machine and therefore you should return it. It really sounds like you need a perfect bird and maybe you will find one.

You mentioned flying after a snowfall which means the temp is going to affect the battery and the bird. I often stay with 10-12 minute flights when it's cold. I adjust to the situation.
You mentioned the altimeter changes during flight. Of course. It's a barometric altimeter and is affected by temp. It provides a rough translation of altitude. A 10-20' error is normal. I can live with that.
Your's drifts a few feet in hover after rapid maneuvers. Yup. That will happen.

If it's 40 degrees and you want to push it to a low voltage warning and still have everything go perfectly, do yourself a favor and find a machine to your liking.