VERY new to the UAV world and recently decided to take a stab at building a quad copter.
On a whim, I decided to buy a DJI Flamewheel 450 frame. It includes the upper and lower boards (lower board has built in power distribution) and the arms.
However....everything else I have bought is from 3dRobotics. Couple questions I have so far:
1) As the ESC's came from 3DR, they come with plugs on the end that are meant to plug into the PDB sold by 3DR. I'm assuming I could un-solder these plugs and solder them directly to the lower DJI board that has a built in PDB? The DJI kit also came with two large wires, one red, one black. I'm also assuming the I could solder the correct plug on to the end of these two wires to plug into a battery pack?
2) The props I ordered from 3DR are huge! 11 inches I think. They seem bigger than the ones I've seen on youtube vids. I bought them as that is what 3DR suggested for the motors I bought from them. Does this seem right?
Sure I'll have plenty more questions down the road :)
Replies
Ah and these are the props I bought.
https://store.3drobotics.com/products/apc-propeller-set-11x47-sfp-s...
Hi Johann,
These are the motors I bought:
https://store.3drobotics.com/products/motor-ac2836-358-880kv-1
These are the ESC's I bought:
https://store.3drobotics.com/products/esc-20-amp-SimonK-1
Haven't started looking at batteries yet but something that can last as long as possible.
Those motors are rated for both 11 and 12 " props so they should be OK. The motors page does not give a proper spec sheet on what the amp usage will look like but I used 880kv motors on a 20A ESCs and they were ok as long as I used 3S lipos. When I run a 4S the ESC were getting very hot. (Given .. they were really crap ESCs)
Both the motors and ESC are rated for 2 to 4S lipos so just make sure you stick to that when you buy lipos.
For the motors the 2-4S are not THAT important but for ESCs that is critical. If you plug that ESC into a 6S, the magic blue smoke will escape.
Kind regards
Thanks for all the info so far, Johann, it's been very helpful.
So I'm guessing the ESC's will be the weak point in my setup and will limit the size of the battery I can use? I noticed on some youtube vids last night that most seemed to be using 30 amp ESC's. Worth upgrading?
I guess for now I could just stick with what I have as I'm eager to get flying and could upgrade down the road.
Magic blue smoke??? Fun!
Hi Clayton.
I'm not a professional by a long shot but I've learned a lot in the past couple of months.
I would stick with what you have for now. Just be smart when buying Lipos. They aren't cheap so buy decent quality and look after them well. Keep to charging and discharging rates and don't store a fully charged pack for long times. Use a good quality balance charger.
I started with 3S 2200mAh and found they are very light and don't offer too much flight time.
I then upgraded to 5000mAh 3S and found them to be quite heavy so they affect the performance of the craft a lot. I then got myself 5000mAh 4S and I love them. I still use the 2200mAh 3S units on my small helli etc but the 5000mAh 4S units works really well on my quadcopter. One of my ESC caught fire the other day and I then upgrade to more decent, higher rated ESCs. I live in South Africa so my choice was very limited but went with the best 30A units with a decent firmware I could find locally.
One thing to keep a close eye on is the temp of the ESC after a flight. When you get started, take off, hover it for a couple of minutes, then land it and check the temps. If they are very hot, that's the first warning sign. Also keep an eye on the temps of the Lipo and the motors. In general motors should not really run that hot. Lipo's do warm up during flights somewhat but if they discharge to quickly they can overheat and even puff up and if they do ... you have a problem...
I know getting into the multirotor thing is quite a daunting task at first, but keep asking questions... There is no such thing as a stupid question when you start. Rather ask a question before needing to replace kit. :D
All the best of luck to you and please post some picture when you are ready :D
Have a good one.
Ok...here's another one for ya as I'm trying to get my head wrapped around cabling and making sure I have everything.
Plan is.....
1) Unsolder the plugs currently on the end of the ESC's, I will then solder the ESC's to the appropriate place (+ & - terminals) on the lower DJI board I have which has built in PDB.
2) DJI kit came with 2 large wires (red & black) with no plugs on either end, I solder THOSE to the main power terminals on the lower board which I believe sends power to the ESC's. Now do the ESC's step down the power as necessary to the motors?
3) And this is the one I need to make sure I have right. The two large leads that I just soldered to the lower board. Obviously the large blue plug on the batter will connect here. Now....to supply power to Pixhawk, that is done by way of the smaller 6 pin connector that is also on the battery, yes? Any need for anything in between the battery and Pixhawk?
1. Soldering the cables to the power distribution board is fine yes. I run mine this way. Just make sure all the red is on one circuit and all the black on the other.
2. The ESC have 3 sets of cables.
a) It has a two cables, normally black and red on one side. those go to the power distribution board.
b.) 3 cables, normally on the other side of the ESC. Those go to the motors .
c.) A thin bacle with a servo plug on them, that goes to the flight controller.
The way it works, in simple terms, the side with the servo plug reads the throttle position on the radio and send enough power to the motors to run at the speed the radio tells it to.
I hope this makes sense.
3. Between the battery / power distribution board and the Pixhawk / APM, you need either a 3DR power module or a BEC (battery eliminating circuit). This steps the power down from what ever the battery puts out to 5.5 volts that the pixhawk / APM uses. Powering the flight controller directly from the battery will blow it up. If your ESC has a built in BEC, then you can power the flight controller from there. If you are using OPTO ESCs, then the ESC does not have a BEC onboard and you will need a separate BEC. I would suggest that you use the 3DR power module since that allows you to use the failsafes on the flight controller which a 3rd party BEC (either on the ESC or separate) does not allow you.
if you need help and find the forum slow, you can add me on skype and I kan talk you through the basics. It's much easier that way. I have helped quite a couple of people this way :D
johannvdventer is my skype name
Hope this helps
Man, you are fast my friend!
Yep, shortly after I posted that I found a diagram that seemed to indicate power is NOT to come directly from the battery.
When I bought Pixhawk, it came with a bunch of cabling including a "3DR power module with XT60 connectors and 6-position connector cable" That's what should be supplying power to Pixhawk?
Also the wiring diagram I found also indicates leads coming from the ESC's to Pixhawk I believe?
I hate being at work at times like this....gets in the way of learning.
I may take you up on your Skype offer, that would be cool. Where in the world are you? Wondering if there may be a time difference that may make that difficult.
Hi Clayton
I'm in south Africa but I'm up at odd times. Chat to a friend of mind in the US every day although there's an 11 hour difference. Makes it fun. :D
The leads going from the ESC to the PX in the thin little cable with the black plug on it (server lead) ...
Black / Brown is Negative
Red is positive
Yellow / White is signal.
There are several ways to power die flight controllers. The manual explains in detail what to do in each of the cases and what not to plug in.
Sorry you have to work. I'm sitting at home wondering if I should go to sleep or continue my copter build (00h21 here in SA now)
Have a good one and chat soon.
Alright, things moving along nicely. All wiring is done and power is fine. Ready for the final assembly and then first flight.
Last question I have for now regards the battery pack. Most pics I've seen of other builds have the batter pack on the top plate. Not sure if you are familiar with the DJI Flame Wheels but that top plate is pretty small. Not sure I have room to place even the GPS mast there.
Any reason why it couldn't be strapped to the bottom plate? Doing so would clear a ton of room for the buzzer and GPS mast and maybe other items down the road. Better on the underside of bottom plate as it still leaves enough room I think for a camera.
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