One of the most often asked questions about any electric conversion is “what controller should I use?”. Controllers are the last remaining voodoo in electric systems, and they are not easy to understand. I have picked up a few bits and pieces over the years, but to be honest, I have to trust in the opinions of other people who are more experienced than me when it comes to controllers.
Our custom builds article (click here to see that) shows several examples of ebikes using RC controllers, which for some reason are called “Electronic Speed Controllers” or ESC. They are tiny compared to the amount of peak amps they can flow. However, they typically could not provide high amps for long, since they were never designed to power an ebike.
These expensive tiny controllers used proprietary software, so…in 2014, a Swedish electronics engineer Named Benjamin Vedder designed an “open source” ESC-style of controller. This meant that anybody could build one from scratch and could also program it with free shared software. You could even alter the software to improve it or add new features. This type of controller is a Vedder-ESC, or VESC.
The first ones were very small for operating a powered skateboard, and similar devices. However, it is easily scalable to any size, and “3shul Motors” is a company in India that has slowly increased the sizes of their VESC models to the point where you can now get one that uses 126V and provides a peak of 1400 phase amps.
I have been hearing about VESC-based controllers for a few years, and I kept an eye out for conversions that used them, and now I am featuring two of those builds here below.
Alien Rides’ converted 2019 KTM
Kevin at “Alien Rides” is located in the San Francisco area. They started out building and servicing small electric vehicles, and fortunately for us, he decided to use his experience to convert several dirt bikes to electric, and share the results.
The CL700 VESC from 3shul is shown at 2:42 in this video, where Kevin does a great job of explaining all of his component selections.
I could type out some of the big points, but Kevin G does a good job of packing this short video with great information. Here’s the snapshot:
Donor Frame: KTM 250
Battery: Custom 126V / 30S pack
Motor: QS 138/70H
Controller: 3shul CL700
Rivv’s Honda 450 Conversion
Endless-Sphere forum user “Rivv” lives in Quebec, in eastern Canada. He hasn’t posted a video yet, but fortunately he did take a lot of pictures of his excellent conversion of a Honda 450 to electric.
Both of these builds use the QS motors that we noticed were getting popular (for our article on QS motors, click here). The feature that ties them together is that they both also use the 3shul Motors VESC, model CL700. This model seems to be a sweet-spot between fit-able size, good power, and affordable price.
Just showing a picture of a controller is not very exciting because they are all pretty much a “black box” that is filled with voodoo electronics. One thing that caught my eye about Rivv’s conversion was the high quality of the build, and the great pictures he took and posted.
QS announced that they will start carrying a model of motor soon that is this larger 180/90H size, and it will include the factory geared reduction that is similar to the motor that is one size smaller, the 165/70.
As of the time that Rivv built his conversion, the big motor didn’t have a factory reduction option, so he decided to build a DIY reduction “jackshaft”. By reducing the output RPM’s he would be able to use common rear wheel-sprockets to adjust his wheel-speed for different conditions, rather than using a custom large diameter sprocket that had a direct chain from motor to wheel.
The pic above shows a plastic 3D-printed dry-fit housing that Rivv made to test the size and shape needed before he ordered an expensive CNC aluminum housing to be made.
Here is the custom CNC aluminum reduction housing, along with the sprockets and chain. The 17T and 11T sprockets provide a 1.54:1 reduction
Here is the Motor, the aluminum reduction jackshaft housing, and a plastic cover.
Here is a pic of the jackshaft from above. Rivv has a lathe, and other machine tools in his workshop, and this build has made good use of them.
There’s not much to say about QS motors and 3shul VESC’s, other than some very experienced people seem to like them, and I have not used them yet.
Much of what I do is “crowd sourcing” knowledge, and I read a lot. I have been seeing people mention using the 3shul VESC controllers, so I was happy to find a couple of builds that had pictures to show.
Controllers can be mounted in any position, especially if they are potted like this one, which means the components inside are completely covered with a mass of waterproof goo, which also provides shock protection. Rivv mounted it upside down under the seat, and added an extra aluminum pad to help absorb heat spikes.
The Battery Pack
Another thing that really impressed me about this conversion was the custom 26S / 107V battery pack (107V when charged to our recommended 4.1V per cell). He decided to use the high-amp cylindrical Molicel P28A cells in the 18650 format.
Rivv drew everything first in CAD
Even with a computer model, it never hurts to use “Cardboard Aided Design”. Here, Rivv built a foam box to verify his battery box dimensions. For roughly the last ten years, most dirt bikes have used the “twin Spar” design of frame, which makes conversions much easier for us electrical builders. The old style had a single top-tube, like a bicycle…and that restricted the battery shape and size.
Rivvs plan calls for a HUGE pack using 14 cells in parallel (14P)
Rivv ordered these custom bus-plates to be laser-cut, and they turned out fantastic. Motorcycles draw high amps, and copper busses have low resistance. Plus, they also act as a heat sponge, to level out the heat from amp spikes.
Here, Rivv is adding grooves to aluminum plate for the protective battery box
This is one of the largest battery packs I have seen on a conversion. It provides high volts, high amps, and long range.
Written by Ron/spinningmagnets, June 2023