ZMR250 Build – Part 6 – Little Bee ESCs
The EMAX 12A ESCs don't support damped light so I ordered four LittleBee 20A ESCs. This video shows a quick comparison between the two ESCs and the effect of active braking.
ZMR250 Build – Part 5 – EMAX 12A ESC Update
In this video I look at updating the EMAX 12A ESCs with a direct connection to BLHeli via an Arduino Uno (as opposed to going via the flight control board). Initial reading of the supported SiLabs ESCs documents indicated it wasn't going to be straightforward. After some Googling I found the video below which shows step by step instructions how to do this.
The alternative would be just to buy one of the EMAX $10 programming cards which I guess is simple enough but then I'll never be able to do BLHeli firmware updates plus I like being able to use the BLHeli to check and set the ESC parameters.
After going through the process of soldering on a wire to each of the four ESCs and updating to the latest BLHeli, I found these particular ESCs don't support damped (damping?) light / active braking which is a bit of a bummer so I ordered four Little Bee ESCs instead. It would be interesting to compare between the two types of ESCs when it comes to flying but I'm not sure I'm up for the hassle of swapping out the ESCs.
ZMR250 Build – Part 2 – Power & ESC Check
In this video I hook up power to the fpvmodel PDB and to the EMAX 12A ESC. I'm trying to decide whether to solder the Sunnysky motors directly to the ESC or to the ESC leads. Removing the heatshrink from the ESC shows what looked like dodgy solder job touching the pins of the ICs. I wondered if they were going to work at all. After hooking up power and successfully testing them, I decided to use the ESC leads to connect to the motors for two reasons;
- Unlike other ESCs that have the three points at the end of the ESC to connect to the motor wires, these EMAX 12A ESCs have them along the middle of the board which means the wires would be staggered (different lengths).
- The connections are inbetween ICs and some of them make contact with the legs of the ICs. I don't want to break the connections with a messy soldering job.
How to connect 4 ESCs to one LiPo battery (Make a power distribution board)
The first time I built a power distribution / wiring harness for a tri / quadcopter was back in December 2010 (http://fangin.com/blog/2010/12/07/tricopter-build-wiring-harness/) and I chose the most direct solution which was to solder all the cables together. I say "most direct solution" because in hindsight, it's not the simplest solution. The drawbacks of this solution include;
- It's more difficult to layout all the wires and get the lengths planned up front.
- Twisting the wire together and soldering 4 or 5 wires at one junction gets messy.
- I tried to link all the wires at one point (http://fangin.com/blog/wp-content/uploads/2010/12/1000000286-Large.jpg) to go into the battery which made it difficult to get the wire into the XT60 connector.
A neater, simpler and all round better solution is a power distribution board where a central, double sided PCB board (copper on both sides) is located centrally in relation to the ESCs / motors and all the wires connect back to this PCB.
What you'll need.
- PCB - Double sided.
- Cutters
- Red / Black Wire
- Solder / Soldering iron
- 20mm heatshrink tube.
- Cut a small board approximately 35 x 15 mm of the double sided PCB.
- Prepare the wires and board by soldering the ends of each wire and the board where the wires will go. You may want to consider orienting the wire to suit the layout of your multirotor. For example an X-Quad you may want to have four wires coming off the board in an X layout.
- Solder the wires to the board. Turn the board over and repeat for the other polarity wires.
- At this point you're almost ready to seal the board up with some heatshrink tube. Before you do! Use a continuity test on a multimeter to ensure 1) All the ground wires are connected and 2) There is no connection between the positive and ground planes.
- If you're worried about wires moving or foreign objects getting into the heatshrink, smother both sides of the board with glue from a hot glue gun. That will help keep the wires in the right place and prevent a short circuit between the two polarities should something conductive work it's way into the housing.
- Now you can solder your favourite connectors at the end of each pair of wires. In the photo shown below I've used XT60 connectors on a harness made for a tricopter.
MWC Quadcopter – Cramming in the ESCs
These photos show the frame starting to come together. The bottom of the CF plate shows each of the four ESCs are held in place by 2mm cable ties. There's not a lot of room left on the top of the board after the ESCs and power distribution cable is laid down. On top of this will come the three leads from each motor to plug into the ESC. If you were thinking of using any gauge wire heavier than 20AWG, you might want to think again because even just space will become an issue.
The next plate above is prepared with nylon mounts to host both the MWC control board and above that will be another quad frame plate that is likely to host my GoPro camera. I haven't decided yet whether to put the camera up on the top plate or out in front on an extended arm. Up top under a dome would be better balanced and protected, but out on the arm might have a better view clear of the props. Undoubtedly I'll end up trying both but seeing as I don't have the extended arm, and it costs more money, I'll see how it goes up top first.
