Lessons learned today: Take heed and enjoy

I was on a survey job for the Sacramento Kings new arena and I discovered a few good tips.

• Set your RTL at %30 of battery drain.
• Carry good electrical tape

• Buy a backup Iris+

• Get a lens guard for your GoPro.

I decided to allow my unit drain to 20% and RTL. I was 60m up and only around 100m away. The Droid lady said "Low battery, returning to launch" Sounds good to me. As it's decending I notice I'm well off the mark and headed into oncoming traffic. It's a tight quarters job and you gotta be ready. I begin to nudge it over the K rail and I hear the motors begin to decelerate. I hit hard left and, well watch the quick video.

The gimbal plate cracked in half but I was able to use electrical tape to finish the job. I had a Mobius on there for shits and giggles and the GoPro was the survey unit. You'll see it fly. Gotta hand it to GoPro. That's one tough unit. I did have a CPL filter on there, but if you can use a cheap 3D printed hood, do it. That filter saved my lens.

So if you're ever unsure out there. Trust your gut and RTL.

https://youtu.be/Tn4qdcMAdPM

One point in all of this that does not seem to have been made is the importance of calibrating your voltage and current monitor - there is plenty of info on how to do this. I do not own an Iris but I believe it comes with a cheap lipo charger. Does it show maH put back into a pack? In any event, if it is a cheap charger, and you are serious about flying UAVs, junk it and buy a good one. Every time you discharge a battery to 20% or so you should check that the mah put back is close enough to what MP says you used. This can be made quite accurate by calibrating it to be accurate at hover current levels - power modules are notoriously non-linear so calibrating them to be accurate at lower throttle will not do. A digital power meter (only $30) is essential for this.

A good charger, as has been pointed out, also tells you when internal resistance is high and lipo condition is questionable.

If you are using FrSky and a Taranis, get an S Port multi cell monitor (only $20) and set your TX to squawk when your lowest cell hits 3.7V. Also use the timer feature on your TX. When the flight times start decreasing then you know your batteries are reaching end of life. I really feel if your TX is not giving you an individual cell readout of voltage, and you have not set it to alarm at 3.6/3.7V, and you are relying solely on combined cell readout in MP, you do not get early indication of individual cell problems. Honestly, I calibrate the 3DR voltage and current monitor so i can have useful dataflash logging but I always rely on my FrSky cell monitor readings on my TX while in flight.

I think battery failsafes are a last resort. Like the "Pull Up" squawk on a jetliner, you never want to trigger one. I have mine set to Land at a voltage lower than I would ever fly it (unless I am flying over water). If you really want to preserve your expensive tool then you really need to get multi cell voltage monitoring and know your batteries performance through testing and calibration. Quite apart from anything else good quality lipos themselves are expensive and easy to damage.

Just my 2 cents.

Replies

Kris Kitchen April 10, 2015 at 5:40pm

Side note if anyone bumps their tiny box camera lense and scratches or chips it, Toothpaste+dremel...
- Jimmy Oliver > Kris Kitchen April 10, 2015 at 6:10pm
  
  I have tried LensRx, Toothpaste, Rubbing Compound... Nothing ever worked. Then again I gouge (sp) my lenses
- Kris Kitchen > Jimmy Oliver April 10, 2015 at 6:14pm
  
  I hate gopro. If I did not have a zillion other things to do that would me my mission to knock them out of the market. That little box...
- Jimmy Oliver > Kris Kitchen April 11, 2015 at 12:11am
  
  I love mine. Swapping out lenses, etc... I just printed these to go over the front. Clips right into the back of the Tarot 2D gimbal. No more screws.
- Kris Kitchen > Jimmy Oliver April 11, 2015 at 5:31am
  
  Got the .stl for that? Nice design
- Jimmy Oliver > Kris Kitchen April 11, 2015 at 11:37am
  
  It's a bit tough to get on at the moment. I'm going to thin it down a bit and make sure the edge can't be seen by the fisheye. Then I will make another version that is level with the build so you can put filter caps on it. Gimme a bit...
- Javier Ruiz > Jimmy Oliver April 13, 2015 at 2:17pm
  
  I too would love the .stl for the final version- those screws are annoying.
This reply was deleted.
- Jimmy Oliver April 10, 2015 at 9:36am
  
  I was 100m high and 60m away. The unit RTL'd at 20% battery and didn't have enough juice.
Kris Kitchen April 9, 2015 at 12:42pm

Great advice. I am a 30% er too.
Marc Dornan April 9, 2015 at 6:34am

One point in all of this that does not seem to have been made is the importance of calibrating your voltage and current monitor - there is plenty of info on how to do this. I do not own an Iris but I believe it comes with a cheap lipo charger. Does it show maH put back into a pack? In any event, if it is a cheap charger, and you are serious about flying UAVs, junk it and buy a good one. Every time you discharge a battery to 20% or so you should check that the mah put back is close enough to what MP says you used. This can be made quite accurate by calibrating it to be accurate at hover current levels - power modules are notoriously non-linear so calibrating them to be accurate at lower throttle will not do. A digital power meter (only $30) is essential for this.

A good charger, as has been pointed out, also tells you when internal resistance is high and lipo condition is questionable.

If you are using FrSky and a Taranis, get an S Port multi cell monitor (only $20) and set your TX to squawk when your lowest cell hits 3.7V. Also use the timer feature on your TX. When the flight times start decreasing then you know your batteries are reaching end of life. I really feel if your TX is not giving you an individual cell readout of voltage, and you have not set it to alarm at 3.6/3.7V, and you are relying solely on combined cell readout in MP, you do not get early indication of individual cell problems. Honestly, I calibrate the 3DR voltage and current monitor so i can have useful dataflash logging but I always rely on my FrSky cell monitor readings on my TX while in flight.

I think battery failsafes are a last resort. Like the "Pull Up" squawk on a jetliner, you never want to trigger one. I have mine set to Land at a voltage lower than I would ever fly it (unless I am flying over water). If you really want to preserve your expensive tool then you really need to get multi cell voltage monitoring and know your batteries performance through testing and calibration. Quite apart from anything else good quality lipos themselves are expensive and easy to damage.

Just my 2 cents.

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This reply was deleted.

IRIS

Replies