Hello,
I sent a message to 3DR support about a week ago and I figured I should just post some questions I had here.
I have this kit on the way today, with the 850kv motors and I am wondering about some things.
1) I plan to run this with a 4S 4000MAh lipo, I have read on different forums that the 3DR apm power module shouldn't be trusted? I would like to be able to monitor the voltage as well as the amp draw, what are everyone's thoughts on this power module?
2) I plan on using a small 5.8GHz tx for video on my quad along with a small ccd camera and a second smaller (1000mah 3S) lipo pack to power them. Are the 850kv motors with the 10" APC Props going to be strong enough for this configuration?
If not, I am thinking about running something like the T-Motor MT2212-13 980kv's with 9x4.5" APC props or possibly the MT-2216 900kv with 11" APC props.
I have been running a hoverthings flip fpv quad with the same fc and gps for a while now, and recently was able to get it tuned correctly and it works great with the latest 3.0 firmware, and it uses the 980kv t-motors with 9" props, one of the problems with this type of frame is to get everything mounted where the apm doesn't have interference issues, I ended up mounting it on the very top of the frame, which I am not comfortable leaving it exposed like this, and I really don't want to install an external compass module. One good crash and it wouldn't be good for the APM.
I'd appreciate any advise, Thank You
Replies
Today I finished up building my quad and testing it, got everything calibrated, compassmot is at 13% which I think is pretty good, I ended up getting a 3S 4000MAh lipo from a buddy of mine, i'm getting about 12 minutes of flight leaving about 1 amp on the lipo. I didn't even have to adjust the pid's for this either which was a nice change for me. Everything works great with release 3.0 on the APM. I even setup a few simple missions which worked flawlessly.
One thing I am looking for is with missions, what is the setting to change the speed at which it will go from waypoint to waypoint? I thought there was a video out there somewhere on what the setting was but I am still looking.
My quad seems to have plenty of power for what I need, just have to get my video tx and ccd mounted and setup...
Have you ever tried GemFan 11.47 AG props (glass reinforced plastic props that come in black, orange or green)? On all of your motors, you will see about 2% - 5% longer flight times. I've tested over 60 props and these (along with one carbon pair) were the best with watts/net lift (lifting themselves first).
I have this same quad and recently got it flying rather well.
I use Traxxas 3S 4000mAh batteries. One battery gets me 10-12 minutes of active flight, about 14 minutes of just hover.
I recently did a test flight with two batteries attached. 19:18 flight time with mixed Loiter and Stabilize.
I had a lot of compass problems with this quad. Where the board comes mounted is just about the worst location for interference. I moved mine up using hex spacers and some M3 vibration mounts.
I get a compassmot of about 55% with this setup and it Loiters and does Auto waypoints very well. I recently crashed this into the post of a soccer net and it survived just fine. Only three broken props, the tower took a good hit and did just fine. I also had a battery die on me at about 200ft and had the quad pretty much free fall into the ground. Broke all four landing legs but the frame and the rest was just fine.
Two things I recommend doing with this quad are to move the ESCs as far out on the arms as you can. The other is to put velcro on the underside of the quad and on the top of your battery. The velcro strap does not hold the battery in very tightly and I have had the battery slip out and dangle from its connector.
3dr power module works great for me. I had problems with drawing the 5v from one of the ESCs and the power module has given me no grief. It doesn't always give you the correct % battery remaining (I get 0% and can fly for another minute or two), but it does a good enough job for rough estimates and the voltage reported is always very close to what I get on my meter.
I am using:
850kV Motors
20A ESCs
10"x4.7 props
3S 4000mAh battery
1.2GHz Video Tx
900MHz XBee
2.4GHz RC kit
I would place much stock in the blog post about the 3dr power module not being trusted. It's far better than most people's home-made power set-ups. I've used many and never had a problem and it's built in voltage and current monitoring is an extra bonus.
Regarding mounting your electronics, what I did was buy a cheap, appx 4" square tupperware-like plastic tub with the snap-lock tabs (the kind sold at supermarkets for food storage). I velcro'd the lid to the frame of my hexa, and put the APM, Rx, telemetry, and Ublox inside.
All I have to do is put the container over the lid and snap the locks closed. It provides a secure crash-resistant enclosure for the electronics. Being transparent, it's easy to keep an eye on the blinkies. I'm very happy with how it worked out.
Good flying!