Strengthening The Battery Box

[Britpilot]

I have just bought a couple of Hobby King’s Turnigy 1300 3s LIPO batteries. The stock PZ battery was already a tight fit in the battery compartment of my SC-LP and the Turnigys are a few mm longer and they would not fit in the battery box. I decided as I was going to have to modify the battery box to make a bit more room I might as well go ahead and carry out the BB strengthening mod as well.

I was going to use popsicle sticks as the others had done but decided to use some 1.1mm alluminium sheet instead as this would be stronger and hold self tapping screws better. Also I wanted to use some “rivnuts” threaded inserts for the strut mounting screws and it would be easier to install these in alluminium sheet than a fragile popsicle stick.

I cut two pieces of alloy sheet, 76 x 20mm for the front strengthening strip and 74 x 22mm for the rear. I used theses two strips as templates on the fuselage and removed foam with a soldering iron to allow the strips to sit flush with the fuselage bottom. I also removed some foam from the fuselage forward bulkhead for a little extra room for the longer battery. I marked the position of the strut screws on the rear strip and inserted two rivnuts.







I scratched the back of the alloy strips to allow epoxy to adhere well and also added a little epoxy around the rivnuts to make sure they would never work loose. With a well greased screw in the rivnuts (to stop epoxy getting into the threads) I epoxied the two alloy strips in place.







After cutting out part of the front of the stock BB cage make battery room I reassembled the battery box using three self tapping screws to fasten the BB to the forward alloy strip. This is what it looks like all back together with the struts now held by # 6 screws and not self tappers. It’s amazing how much firmer and sturdier the whole battery box assembly has now become.





Here is a few more pictures showing where I cut out the battery cage to allow the longer LIPO to fit. Also note the small groove (shown by pencil) that I filed in the right side of the BB to allow the power leads to be out of the way when sliding the battery in.
Darn it PZ why did you make this thing so tight!

[Dillzio]

Rivnuts eh? Never heard of them before but you seem to have implemented them quite well. A very nice, tidy looking mod.

Now that you have the battery sticking further back, has it made the plane tail heavy?

[Britpilot]

Actually the battery is slightly forward by 4-5 mm as it was the front of the battery cage I cut out along with a little of the foam bulkhead in front of the battery cage. Look closely at the pictures.

Links: Rivnut tool: www.aircraftspruce.com/catalog/topages/rivetnuttool.php
Rivnuts : www.aircraftspruce.com/menus/ha/rivnuts.html

[SCC]

Excellent mod there Brit. Very neat and thanks for the pics.

[Britpilot]

Thanks for the compliments. I am now modifying the wing by inserting a carbon fibre spar. I'll post pictures of this along with my CF rigid strut mod when it's all finished.

[jons35]

Hey I like your mod. But does anyone know a way to strengthen the battery box without doing all that work mine keeps ripping out no matter how much epoxy I put on it. And second were did you get the metal for the landing gear.

[N4768Z]

The above mod looks really nice but if you're looking for something with a little less work try this mod. This guy does a great job of explaining each step. I'll be performing a few of his basic mods as well very soon. So far the only thing I've done is add bigger wheels and pack tape the weak areas. No probs with the batt box yet.

www.youtube.com/watch?v=BjtM_faxRu4

[N4768Z]

I like your battery box mod for allowing more room for the batt. I have a second batt that's a fuzz too long. I'm going to try this mod today and see if I can't make a little more room. I'm deff a fan of the wirelead to get them outa the way while installing...what a pain.

[jons35]

Hey thanks for the nice video. I'll try it. and that guy has some really nice videos on youtube for just about everything.

[Britpilot]

The metal I used for the landing gear is cut from a piece of alluminium gutter. Here is the link to my post showing how I strengthened the landing gear:

supercubclub.proboards.com/index.cgi?board=whls&action=display&thread=2664

[happydog500]

How come you only put holes in one, but have screws in both?

[Britpilot]

I had to fix the rivnuts in the rear plate before bonding the plate into the fuselage. The screws in the for'd plate are self tappers and I drilled the holes for those after the plate was bonded in place. I had to do this as I reused the stock BB plastic rectangular securing plate. When this was reinstalled I drilled new holes in-situ through this and the alloy plate for the self tappers.