Hi, We recently got our Alta and we've been setting it up and doing some test flights. Everything's been alright until recently, when we started to get the solid red alarm light mid-flight (flying in Height hold mode). This has happened at least three times now, and we have always landed right after we got it. The strange thing is that everything seems to be fine, and there's no errors in the app. It also flies well despite the warnings, no issues there. From the manual I read that it can be either a "critical error" or the battery voltage dropping below user-defined levels. But last time it happened the voltage was well over 22V, and I've set the warning level to 21,6V (3,6V/cell) The only thing we can think of is that we were flying it in cold conditions. (temperature was -8 celsius) We tried to keep the batteries warm until the flight, but it's possible that they were cold when we got in air. Could it simply be the cold weather doing some funny things in the systems, resulting in an error? And if so, how should we react to that? Also, how come that there was nothing showing up in the app, not even in the terminal? Btw, it would be nice to be able to tell whether the solid red warning light comes from a critical error or battery voltage drop. Thank you for any help! Otherwise the copter has been great and so far we are very pleased with our purchase
i think it is the voltage warning. set the warning lower (3,3V) and test it while flying. batteries are "well over" 22V: do you mean well over while flying or when you test the batteries on the ground? this makes a BIG difference. i would fly the copter with ALTA app opened and then you will see whats happening while flying. Flying at -8° celsius will result in lower flighttimes even if you warm up the batteries. but this shouldn't be that much. I flew couple of days in similar conditions and still had nearly the same flighttime (a bit less).
As Rolf said, "loaded" (in flight) voltage is lower than "unloaded" (motors off) voltage. What are you using to measure the voltage? And if you're using an FPV camera with the ALTA OSD (onscreen display) you can see the voltage right on that screen. Or you can use the app if you're hovering close to your ground position. I would also lower your voltage warning level, and monitor it whilst in flight. I generally check immediately after launch, and then I have a timer that goes for 8 minutes, after which I start checking again. Depending on camera payload, I get a total of 12-20 minutes of flight time. But I generally do not do multiple takeoffs/landings on a single battery. Maybe two, but that's it. The takeoffs can significantly impact your LiPo batteries. Which batteries are you using?
Aleksi: Can you access the Synapse flight logs for such a flight and post on the forum. The flight logs are .csv files stored on the GPS unit under the small rubber cover on top of unit next to the antenna. Put the microSD into an adapter and plug it into a computer and it should present as a disk drive. You may need to compress the files as they are pretty large. Please post a message if they are still too large and I'll tell you how you can send the compressed file to me. Andy.
Thanks for all the replies. Andy, I've attached the flight log for one of those flights. I think this one went well for a couple of minutes before the red light appeared. The voltage was over 22V when in air, so it was "loaded". When we landed and waited a little, the voltage went up to over 23V. I used the Futaba controller's telemetry monitor to check the voltage. (also the app, but I think they come from the same source?) We will be flying again today, and now it's not so cold (around 0 degrees celcius), so we'll see if it goes any better now. We're using the Freefly's own 10Ah Flight Packs as batteries.
Thanks, Aleksi. I've download the file and I'll run it through the Synapse Log File Converter and let you know what I find. Andy.
Aleksi: Here are the files output from the Synapse Log File Converter: The metrics file (which I've included as part of this posting below, shows a summary of the flight. you mentioned that the low voltage warning was set to 21,6V. As you can see the lowest voltage recorded in the log file is at IMU Time of 245.7822 seconds. (The IMU Time is a very accurate clock maintained by the Inertial Measurement Unit and provides a time stamp for each row of the Synapse log file.) The gpx file can be input into MK_GPXTOOL -- which was originally designed to analyze Mikrokopter flight logs but is sufficiently general purpose that I can convert Synapse log files into a suitable form where you can use MK_GPXTOOL. The .kml file can be used as input for Google Earth. The logbook.csv is just a short output file that you can use if you are keeping a flight logbook in Excel, LibreOffice, or Google Sheets. What I need to do now is stare at the actual data in more detail to see what was going on with the battery voltage. The Synapse Log File Converter records the *lowest* voltage, not necessarily the first occasion where the voltage drops below the preset "Low Voltage" alarm level. Andy Synapse Flight Metrics created by: sflc Version 3.02 2015-12-11 Copyright (c) Johnson-Laird Inc. Flight date (UTC): 2015-12-15 PHYSICAL METRICS Flight duration: from 10:11:45 to 10:15:39 (UTC) : 234.122 seconds (0:03:54.121 H:MM:SS.m) GPS Base Altitude = 19.1m Home Latitude/Longitude = 65.048723 N 25.568318 E Bounding box for flight from home (meters) based on IMU data: North = 29.27 South = 21.05 East = 2.72 West = 23.70 Up = 9.29 Down = 0.96 Bounding box for flight from home (meters) based on GPS data: North = 29.25 South = 20.98 East = 2.67 West = 23.61 Up = 9.33 Down = 0.94 Maximum horizontal distance from home: IMU = 37.48 meters GPS = 37.42 meters Maximum slant angle distance from home: IMU = 38.28 meters GPS = 38.22 meters Horizontal distance flown: IMU = 198.90 meters GPS = 195.99 meters Flightpath distance flown: IMU = 222.76 meters GPS = 229.43 meters Synapse Flight Control Data: Flight Controller Boot-up Temperature = 22 C at IMUTime 1.0540 seconds Flight Controller Max Temperature 22 C at IMUTime 1.0540 seconds ELECTRICAL DATA Maximum Battery Bus Current = 84.30 Amps at IMUTime 54.5673 seconds Minimum Voltage = 21.56 Volts at IMUTime 245.7822 seconds Maximum Power = 1898.60 Watts at IMUTime 54.5673 seconds Hover Power = 841.59 Watts Hover Battery Bus Current = 38.50 Amps Hover Throttle = 1320 microsecond pulse, 32.1% Charge used = 3.6 Amp hours Energy used = 79.1 Watt hours Energy efficiency = 0.3551 Watt hours/meter traveled ESC/MOTOR DATA Pre-flight ESC Temperatures (check for ESC/Motors already too hot): 1 = 13 C at IMUTime 20.9752 seconds 2 = 14 C 3 = 10 C 4 = 10 C 5 = 12 C 6 = 12 C Average = 11 C, Odd/CW = 11 C, Even/CCW = 12 C, Difference = 0 C Maximum ESC Temperatures (check for ESC/Motors running hot in flight): 1 = 32 C at IMUTime 246.5018 seconds 2 = 31 C at IMUTime 228.6716 seconds 3 = 32 C at IMUTime 246.1420 seconds 4 = 31 C at IMUTime 198.7280 seconds 5 = 29 C at IMUTime 209.2822 seconds 6 = 30 C at IMUTime 225.0336 seconds Average = 30 C, Odd/CW = 31 C, Even/CCW = 30 C, Difference = 0 C Maximum ESC Phase Currents (check for ESC drawing too much current): 1 = 38.8 A at IMUTime 20.9752 seconds 2 = 43.4 A at IMUTime 248.5806 seconds 3 = 39.3 A at IMUTime 248.5407 seconds 4 = 37.5 A at IMUTime 20.9752 seconds 5 = 47.3 A at IMUTime 21.0152 seconds 6 = 32.5 A at IMUTime 54.7272 seconds Average = 39.8 A, Odd/CW = 41.8 A, Even/CCW = 37.8 A, Difference = 4.0 A Minimum ESC Volts (check for ESC operating at too low a voltage): 1 = 20.89 V at IMUTime 230.9104 seconds 2 = 21.42 V at IMUTime 206.6037 seconds 3 = 21.37 V at IMUTime 185.0556 seconds 4 = 21.58 V at IMUTime 237.4667 seconds 5 = 21.30 V at IMUTime 248.5806 seconds 6 = 21.50 V at IMUTime 208.1229 seconds Average = 21.34 V, Odd/CW = 21.19 V, Even/CCW = 21.50 V, Difference = -0.31 V Maximum ESC RPM (Spds) (Check for motor spinning too slow): 1 = 4432 RPM at IMUTime 161.7084 seconds 2 = 4483 RPM at IMUTime 61.1237 seconds 3 = 4494 RPM at IMUTime 183.3365 seconds 4 = 4448 RPM at IMUTime 105.0195 seconds 5 = 4402 RPM at IMUTime 92.0267 seconds 6 = 4366 RPM at IMUTime 54.9271 seconds Average = 4437 RPM, Odd/CW = 4442 RPM, Even/CCW = 4432 RPM, Difference = 10 RPM Maximum ESC Power (check for motor consuming too much power): 1 = 347.5 W at IMUTime 54.7272 seconds 2 = 457.3 W at IMUTime 248.5806 seconds 3 = 420.0 W at IMUTime 248.5407 seconds 4 = 377.3 W at IMUTime 207.9630 seconds 5 = 336.8 W at IMUTime 54.8071 seconds 6 = 365.5 W at IMUTime 54.7272 seconds Average = 384.1 W, Odd/CW = 368.1 W, Even/CCW = 400.0 W, Difference = -31.9 W Maximum ESC Power Recovery (check power recovery operating): 1 = 93.4 W at IMUTime 249.0604 seconds 2 = 98.6 W at IMUTime 249.0204 seconds 3 = 97.3 W at IMUTime 249.0604 seconds 4 = 84.7 W at IMUTime 249.0604 seconds 5 = 73.3 W at IMUTime 249.0604 seconds 6 = 56.7 W at IMUTime 249.0204 seconds Average = 84.0 W, Odd/CW = 88.0 W, Even/CCW = 80.0 W, Difference = 8.0 W Maximum ESC Energy (check for ESC/motor consuming too much energy): 1 = 12.8 Wh at IMUTime 247.5412 seconds 2 = 12.9 Wh at IMUTime 248.4207 seconds 3 = 15.1 Wh at IMUTime 248.2608 seconds 4 = 14.6 Wh at IMUTime 248.0609 seconds 5 = 12.9 Wh at IMUTime 248.0209 seconds 6 = 11.6 Wh at IMUTime 248.1009 seconds Average = 13.3 Wh, Odd/CW = 13.6 Wh, Even/CCW = 13.0 Wh, Difference = 0.6 Wh Maximum ESC Acceleration (check for excessive vibration): 1 = 40.00 at IMUTime 203.6054 seconds 2 = 32.90 at IMUTime 197.1289 seconds 3 = 27.50 at IMUTime 200.8869 seconds 4 = 32.80 at IMUTime 217.4378 seconds 5 = 35.70 at IMUTime 204.2050 seconds 6 = 37.40 at IMUTime 231.5100 seconds Average = 34.38, Odd/CW = 34.40, Even/CCW = 34.37, Difference = 0.03