Q1. Should a individual ESC (not a 4in1) be mounted close to the Flight Controller (long motor wires) or mounted close to the motors (long ESC to FC wires) and what is the reason for this?
Q2. What is a practical method of mounting single ESCs to the frame that overcomes exposed ESC connections and movement (vibration)? 3D printed mounts seem a good solution but that involves designing and printing them?
@xfacta Thanks.
Any tips on attaching ESCs to the frame?
Best practice is generally to keep ESCs out of autopilot range (because of the internal compass) to avoid interference with the compass due to EMI generated by each ESC when the drone draws current. You may face compass variance issues.
Best practice is to mount ESCs near the motor; if current consumption is 50–60% of esc capability to avoid heating and natural cooling of propellers air.
I’m not sure where that comes from. There’s some ESC manufacturers where there is no option because ESCs are integated in the motor mounts. This doesnt mean it’s the best thing to do, they are considering the commercials and scope for people to incorrectly mount or wire the ESCs.
Properly sized motors and ESCs, along with correct tuning, means the ESCs rarely would need that airflow. The ESCs I’ve set up only just run warm.
Hot ESCs should be setting off alarm bells.
If you do that you will need large smoothing capacitors on the ESC inputs otherwise you will get voltage spikes that will decrease lifetime of your ESC or damage it.
What is the reason for this?
Essentially, the extra inductance of longer power wires to an ESC is bad, increasing voltage spikes at the ESC and reducing how much power can be given back to the battery during braking. This heats the ESC more than necessary and can cause shorter life or premature failure.
Lengthening the motor wires has almost no detrimental effects provided you use the correct sized wire and keep all the wires close together.
Here is just one of many summaries if you do bit of a search:
https://www.rcgroups.com/forums/showthread.php?952523-too-long-battery-wires-will-kill-ESC-over-time-precautions-solutions-workarounds
I can personally confirm that a basic ESC will die if the motor is turned without connection to a battery - this illustrates the effect of the inductance in the power wires. In fact not only did the primary function of the ESC die, the 5v BEC died and killed the receiver and other ESCs connected.
Sure, some ESCs are better than others, but why push their limits.
This question is at core of many problems:
3D printed mounts for ESC is a no go, your temperature may go as high as 120C. (I have been running a 30 mm 4 x 1 ESC at 25 A x 4, and outside T reached 115C, with thermal shutdown preset at 140. So not even ABS plastic is very safe, and definitively not the PLA. ESC itself does not care about vibration (except for the soldered cables).
@xfacta Thanks for the comprehensive explaination! Very helpful.
I’m still looking for guidance on how to attach single ESCs to the frame of a large multirotor. 3D printed mounts don’t seem a good idea. Thanks @Michail_Belov.
Heat shrink rap them and then wire tie them to the frame seems the only option but very messy?? There must be a better way???
How your ESCs mount to your airframe is greatly dependent upon your airframe design. Hard to give advice without pictures of the airframe.
I do not like heat shrink, because it reduces cooling. Unless you are doing a coptr for someone, the fact that ESCs are just tied to frame does not affect its performance, and air resistence is minimal. But one has really to see the airframe
3D print mounts would be OK provided you dont fully enclose the ESCs, let some air circulate.
After you’ve done the soldering, connections and cleaned any residue you can spray the ESCs with conformal coating to keep out moisture and corrosion. Some ESCs are already coated but soldering breaks that seal.
Here is the frame. The FC sits on a plate which screws in the bottom plate. Usual story - not much room! A 3D print could be the most practical?
I have 3D printed mounts for ESCs and other things (while leaving some portion open for airflow) out of PETG and have had no problem. That being said, I spec my ESCs so they are only slightly above ambient temperature under load.
I have a Tarot 650 Sport. I chose to mount my ESCs in the body as opposed to underneath the motors as I didn’t want to add capacitors. The Tarot was not designed to accommodate ESCs within the body so I had to add an additional plate - it is a triple decker. The bottom deck is for the power module, power distribution and ESCs. The middle deck is where the arms are connected (along with the bottom of the top deck): and connections made to the motors, the gimbal controller and landing gear controller.The top (flight) deck is where all the flight/navigation and telemetry electronics are mounted.
@FossilRider That sounds a good solution! Any chance of a photo? I assume the battery is beneath the bottom deck and beneath that is the gimbal and camera? Any problem with the ESC’s without capacitors?
p.s. when are manufactures going to make frames that have room for all the extras???
Good work, that sounds great. The old Tarot frames didnt have much space because of the folding arms and you always ended up with brackets and things hanging of the sides.
Sorry for the long absence. Yes, the lipo is mounted underneath. I did this with a previous build and had no problems with the ESCs. I am posting a new topic replated to my build upgrade. I have trouble posting pictures due to file size limitations posed by the website. My email is: brianphillipbuckmaster@gmail.com - send me a note and I will reply with pics.
