Symptoms: Flamewheel 450 twitches down on one arm, not the same every time, and sometimes, instantly flips over as if one prop suddenly lost power.
The cause is a quality control issue with the bullet connectors on the motor and the sockets on the Opto speed controller.
The bullet connectors have a cage with a split. The problem is that when inserted, the split closes but the inside diameter of the now-closed cage is larger than the pin on the male bullet connector. This leads to weak or intermittent contact, and is evidenced by a little slop in the connector when inserted--it can easily be rotated or pulled in and out a fraction of a millimeter as if loo
se.
The fix is twofold. First, one must use a small wire cutter to snip one section of the cage so as to widen the split. The second is to make a narrow strip of thin (0.002" thick) copper. Fold the strip, insert the modified connector into the strip in the socket, and no more problems. The photo shows the strip and modified connector. Every one of the 12 connectors on the Flamewheel 450 kit I bought in December of 2012 has this problem.
Comments
Most ESCs allow easy cutting off the connectors and soldering of the wires, unfortunately DJI Opto ESCs do not since the bullet sockets are physically mounted to the end of the ESC.
You could either solder the connector itself together or solder a wire into the bullet socket, but the heat transfer through the socket could quite easily cause problems where the socket is attached to the interior ESC board.
Presumably you might need to remove the large outer heat shrink from the ESC, remove the sockets and solder wires directly to the ESC boards.
Albert's solution with the copper foil is looking pretty good.
Alternatively does anybody know of an appropriately sized "good" bullet male connector that will fit in the DJI ESCs as John suggests.
The XT60 battery connectors that we all love, are just 3.5mm bullet connectors with housing added. If you look at the the bullets in the XT60, you see how to properly design them as a solid piece of metal without the flimsy press fitted cage.
I had a similar issue with a female Deans connector that came attached to two new batteries. While the physical fit was fine, the electrical contact was not. I believe this caused the twitching that I was getting before I changed the battery connector.
If I ever have problems with the bullet connectors between the speedos and the motors I'm going to cut them off and solder the wires together.
The problem was there at the very beginning when brand new. Obviously, its not everyone that has it, but I do comment that when you change or reroute anything, tension on the leads can change and make things either better or worse.
High current bullet connectors are very good, in fact some of the best around.
The problem is the "bullet" connectors with press fitted cage around them, that has become popular for some reason. They are not suited for the task. A real high current bullet connector should look something like this.
The DJI bullet connectors are not very good. Eflite (and others) make a decent connector, but switching the socket from the board isnt the easiest thing to do. If the speed controls were direction programmable, I would solder the motors directly to the board. I am running an F550 with all DJI power and so far so good, but I fully plan on ditching these connectors and would suggest everyone else does as well.
This is the thing I don't understand... I had a NAZA right before I bought the APM2.x kit. The NAZA NEVER dipped an arm. AS soon as I set up APM thats when it started. But I ended up rerouting and coiling the ESC leads. after that If flew BEAUTIFULLY, I mean as good as the NAZA, in my opinion. I think that there is more noise being radiated than the NAZA, but for me coiling the ESC leads did the trick.
Bullet connectors are always a problem,but I have two F450 kits (one of them installed on an F330) and although my connector(s) look like yours, they currently at least, are very positive in their fit and have no play at all.
And I have experienced no indication in flight that there is ever an intermittent connection. (Quads do not tolerate those well at the best of times.)
Is this a problem that occurred right away or after several insertions removals.
In any case I will definitely keep this in mind and institute your fix if it ever becomes a problem.
There are a LOT of people out there with these Flamewheels with the DJI motors and the Opto ESCs and I picked them largely for the robustness and general satisfaction with the whole system.