Battery bag for my E-Bike

Last weekend we borrowed a sewing machine to make new curtains for the apartment. When I was sewing the curtains I realized that It wouldn’t be very difficult to make a custom battery bag for my e-bike. I would like a bag that I could mount in the frame triangle and have room for 4 Turnigy 6S 5Ah batteries. Doing some measurements, calculations and drawing I came up with this design

Battery bag drawing
An outline of the battery bag, the red triangle is the frame, the blue rectangles are batteries and the gray rectangle is the controller mounted on the frame.

I went to the fabric store and found a black nylon fabric that had a PVC layer on one side. This should be fairly water resistant and I plan to spray it with some textile waterproofing spray as well. I was recommended to use a thread for furniture which is much stronger than ordinary thread as well. A couple of hours thinking, cutting, and sewing later:

Battery bag
I use some Depron in the bottom, and some foam in the two corners to protect the batteries and fill out the bag.
The zipper has a bit of fabric folding over it for water protection
Hole for cable
The hole for the cable is also waterproof since the side of the bag overlaps ~10 cm where the cable comes out.
I'm using the cable I made for the E-Puch. This cable is for two turnigy batteries in series and two in paralell with a 60A fuse. The LEGO part is just for size reference.
Everything fits nicely inside the bag

The bag fits perfect on the bike!

Battery bag on bike
Battery bag on bike
Battery bag in frame
Battery bag in frame

Pleas write a comment if you think I should make some kind of drawing and description on how to make a bag like this.

Plans for my depron plane

Final CAD model of depron aircraft
Rendering of the aircraft


In a comment on the post about my first Depron RC-plane I was asked for the plans. I’m afraid I don’t have the nice 1:1 print on multiple A4 plans that most people are used to, but if someone have a good guide on how I create those kinds of prints I’ll be happy to create one. But for now I can provide the drawing with measurements.

Depron Plane drawing
The drawing of my depron plane (all measures in mm)

And the same drawing as a PDF

I measured up these parts on a piece of cardboard to use as a template. Especially since you need two of all parts except the one in the lower right.

I used the kind of cardboard that you can buy at a painters shop to protect your floor while painting.

Some catching up to do

No posts for a couple of days since I’ve been busy with other things. As you may have noticed, to this point, I have only written about some old projects I’ve done in the past. There is some catching up to do but I will mix old projects with new stuff until all my old projects are well documented here (at least the interesting ones).

Here are a list of projects I will try to write all little about in the near future.

  • One more Depron RC aircraft. (SAAB J-35 Draken)
  • More about my quadrocopter
  • At least two electric bikes, one MTB and one Puch Maxi Moped conversion
  • Electronics for electric bikes, controller and motor modifications, BMU, DC/DC converter, LED-lights…
  • Mechanics for electric bikes, motor mount, battery box…
  • Maybe some pure programming projects for either Android, Windows or the web

First try on depron RC aircrafts

This will be my first project post on this blog starting with something I made a year ago. A RC aircraft made out of depron.

Depron is a foam material intended for insulation and sound dampening of floors. I bought a 10-pack of 6 mm and a 10-pack of 3 mm at Hornbach, a local hardware store, which will be enough for several planes. At this store the foam was actually called Ebisol instead of Depron, but I guess those are just two different brands of the same stuff.

There are thousands of freely available plans for such a model only a google search away but I had to design my own. Some time behind a CAD program I ended up with this.

Final CAD model of depron aircraft
CAD drawing of depron aircraft

If I were to build this model again i would definitively make some changes to the plans. Some parts of the model were very hard to assemble due to their complex shapes.

A couple of evenings of assembly and some inspections from the chief engineer

Wing inspection
The chief engineer inspecting the wing construction

The model were done.

Foamie done
The aircraft is done, waiting for electronics to be installed
Topside done
Electronics installed
Ailerod servos installed
Aileron servos installed
Elevator servo
Elevator servo installed

Almost all parts I used for this were bought from Hobby King

Radio – Hobby King 2.4Ghz 6Ch Tx & Rx V2 (Mode 2)
Motor – Turnigy 2217 20turn 860kv 22A Outrunner
ESC – Hobbyking SS Series 25-30A ESC
Servos – HXT900 9g / 1.6kg / .12sec Micro Servo
Battery – Turnigy 2200mAh 3S 20C Lipo Pack
Horns & hinges – Plastic Parts Set 29pc (horn hinge)

Apart from this i bought some carbon rods and some piano wire from a local RC store.

The only thing left to do were the test flight

That was the end of that aircraft. I’ve heard people say that the center of gravity was off making the plane unstable. I believe Murphy was trying to teach me a lesson that I should try to walk before I run. Maybe I should have used one of the existing plans known to work with a well defined spot for center of gravity.

As I said this was a year ago. Two weeks ago I visited Aeroseum which is an aircraft museum here in Gothenburg. By now my emotional wounds, from seeing hours of work crashing to the ground, have healed and i feel ready to make a new try.

More about that in a future post…