Extending the CX20 Battery Bay

I have purchased a 3200Mah Lipo for my CX20, and the battery bay is too short to fit it. After a bit of basic design work and examining the structure, I had a plan....

I opened the shell of the CX20 and made sure there were no wires in any peril. Measuring the battery and all the plastic several times over,

I took a Dremel and cut into the belly just where the front curves up. I cut the sides just where there are 2 vertical plastic stiffeners. I left the narrow strip at the top (about 4 MM) intact since it provides structure in tension. It wasn't much but it would have sagged otherwise (I am over 50, trust me, I know about sagging, lol).

Now to refine the sizing.

And work out the shape of the extension.

Since I was doing some body work anyway, I decided to install the FPV camera in this housing. And while I was doing this. Install a headlight. More on this at the end of the article.

A test part made of cardboard and tape lets me refine the shape and the fit before I cut the actual materials.

Speaking of which. I picked up some 40 thou (.040") Styrene plastic sheet at the plastics dealer. It's a little soft on it's own. I Glued some balsa to the back of the plastic. I used Gorilla Glue. I put a little plastic glue on the styrene and the gorilla glue on the balsa. Use some cellophane to contain the mess, and place this between two boards with some weight overnight.

...unfortunately they slid a bit.
Note to self, a strip of tape would reduce the chances of this.

 trimmed off the excess balsa, then did one final fitting with some more cardboard.

With that final set of shapes, I cut the bottom and side panels of the box.

The front plate is easy to work out at this point. I carefully ground out the hole to fit the LED diffuser and the camera. The flipped open top was for figuring out how it was going to be finished.

I was going to build the cover from strips built up. but the thing was not working out.

Using a few bits of thicker balsa, I was able to build a different cap and shape it to mate with the upper shell. I glued in a strip of 1/8" ply for a screw point and a block in the bottom half for the screw to attach to.

A little foam as a means of keeping the battery from moving around worked well.
The 3200Mah battery fits in with ease. It fits like a dream. The 5500mah battery is just a little too thick to fit in the extension. I could have made it a little bigger but this was done before the 5500's showed up.

The point of this extension is to house the larger batteries with the door closed, and to house the FPV camera and the LED headlight.


Now the headlight..... I ordered some high intensity LED headlights from Banggood.

http://www.banggood.com/Stunning-Highlight-LED-Night-Light-for-Multicopter-p-917959.html

They are cheap and intense, remember that they need 3V, not 5V.

Some are to be fixed and work with the FPV camera as well as help with orientation and navigation.

My further plan is to put 2 on the Gimbaled camera too (so that they can tilt and pitch with the camera.



......Now most of you have access to a Costco. Look for a 3 pack of headlights like this.

These are a perfect source of a similar LED that runs off of 5V.

I find it funny that you have to open the back to see the instructions telling you that you can open the back.

3 screws in the battery compartment will let you open it up.

The little circuit board contains a switch and a tiny chip. You can't really use it, BUT if you can, you can desolder the surface mounted resistor and wiring it inline with the LED. alternately get yourself a ballast resistor and wire it in series. I have a 5V BEC rigged inside and hotglued in the LED and it's diffuser. It puts out light like a huge amount of light in a tight beam. For FPV when you are looking in shadows, it's quite handy.