UM Cozy...

I recently added a UMX Radian to my stable of aircraft.  I love it... All except for one little problem.  I have several models which use the 1S 150 mAH batterys so I have gather quite a collection of them.

However the UMX Radian uses a strip of velcro to attach the battery.. on the bottom, which is incompatible with my other aircraft (nCPX, nQX and Spitfire).  This has made it difficult to share batteries between aircraft  or with father for use in his Champ which also uses the velcro method.

Inspired by the "Cozy" made by the the FT crew for "RTF Quads review" in Febuary to keep their batteries warm, I have made some "Cozys" to protect my external batteries for my FT power pod based planes (but that for a different article if anyone is interested.)  From there is was an easy jump to a UM "Cozy" for attaching velcro based batteries, so I can use all of my batteries in all of my aircraft now :) 

It's really simple to make but since several people commented on using the idea, I thought I would share how I did it and maybe save you some time.  Maybe overkill on the post, but here it is.

Mark a piece of posterboard in mm at 6,6,12,6,6 and 25mm tall.  The center 12mm side will become the bottom of the "Cozy" and the outer 2 segments form the top.  The 2 segment top method will keep us from having a stress point on a corner and allow us to easily reinforce this area later on.

Cut the outer lines.

Then using the BACK of the blade so as not to go all the way through the posterboard score each of the remaining lines.  Usually 2 light passes works well for me.

"Break" the creases you just scored by folding them back away from the marked side of the posterboard.

Then fold back around so that the marking are on then inside, overfolding slightly to help reach the final shape.  Check to make sure the tops pieces meet cleanly and the corners are all square.  If not, now is the time to trim to fit, or start over if it's too small.

Now that the folds are established, unfold and cover the inside (marked side) of the cozy with tape, and trim away excess tape.  This protects the areas weakened by scoring and add a bit of waterproofing as well, whcih never hurts.

Loosely fold it back into shape.  Tape the outside starting in the middle of one of the sides, going around the bottom and other side, then holding the top pieces flush while wraping across the top.  Finally, cut the tape to end in the middle of a panel, since corner cuts tend to curl up and pick up dirt.  (It looks  better and last longer.) Trim the ends of the tape hanging off the "Cozy".  This is also a good time to trim up the ends of the posterboard if they don't line up perfectly and you want it to look perfect.

At this point you will notice the top of the "Cozy" is slightly out of shape, so its time to fix that, strenghten the seam and tighten everything up to ensure a snug battery fit.
Cut another small piece of posterboard to 11mm x 25mm. (You can cut this at the same time as the main piece, but the for descriptive purposes I have made it separate.) 

Tape one side and trim tape length wise as shown.  I like to cut tape (very lightly) on a silicone mat to ensure the glue on the tape stays clean and doesn't get stretched by removingit from the cutting surface.

Verify that the "Cozy" top is up and the sticky side of the tape is up, push something thin and non-paper (scalpel, pushrod skewer, etc) through the "Cozy" tacking  it to the tape and gently pull straight through. Line the doubler up with the edge of the "Cozy" and wrap the tape snuggly around the top at each end, doubling the thickness of the top layer.  It's hard to see in the (second) picture but it does make a big difference.

Apply Velcro to the Top of the "Cozy" and you are done. 

Total Weight 0.4g, which is pretty close to nothing in my book.

You can eve finish it in tape to match your model such as this one to match the yellow Champ.

This also works great for the 2S UMX series as well using the measurements  9,12,18,12,9 by 30 with a 17x30 doubler.  Watch where you put the velco as some aircraft take them stacked and others use side-by-side.  I put one on each top and side so the "Cozy" works in both orientations, but you could also create a "Cozy" for each model.

A final note on velcro.  The velcro the Horizon uses on their batteries it pretty tough stuff.  Be careful taking it off as it tend to pull off the labels.  It will also leave a fair amount of residue.  While the "Cozy" works with the residue because we taped the inside, it can be difficult to get the batteries in and out.  Removing the residue machanically is nearly impossible and chemically tends to remove the label as well.  My recommendation is to just put a piece if tape over the residue and CAREFULLY trim it. (LiPos to not like to be damage at all.. they tend to catch fire.)  You could trim it first or just smooth it around the sides.  Just be careful.
Hope this helps you as much as it has me. 

Questions and comments always welcome.