One of the most common questions about any power conversion is “what controller should I use?”. Controllers are the last remaining sorcery in power systems, and they’re not easy to understand. I’ve learned bits and pieces over the years, but honestly I have to trust the opinions of others more experienced than me when it comes to controllers.
Our custom build article (click here to view it) shows several examples of electric bikes using RC controllers, which for some reason are called “electronic speed controllers” or ESCs. They are small compared to the peak current they can flow. However, they are generally not capable of delivering high currents for long periods of time because they were never designed to power e-bikes.
These expensive microcontrollers use proprietary software, so… In 2014, a Swedish electronics engineer named Benjamin Vedder designed an “open source” ESC-style controller. This means anyone can build one from scratch, or program it using free shareware. You can even change the software to improve it or add new features. This type of controller is Vedder-ESC or VESC.
The first is very small and is used to operate powered skateboards and similar equipment. However, it can be easily scaled to any size, “3shul Motors” is an Indian company that has slowly increased the size of their VESC models and now you can get models that run on 126V and deliver peak 1400 phase amps.
I’ve been hearing about VESC-based controllers for a few years now, and I’ve been following conversions using them, and now I’m presenting two versions of them below.
2019 KTM modified by Alien Rides
Kevin of “Alien Rides” is based in the San Francisco area. They started building and servicing small electric vehicles, and luckily he decided to use his experience to convert a couple of off-road vehicles to electric and share the results.
3shul’s CL700 VESC is shown at 2:42 of this video, where Kevin explains all his component choices very well.
I could hit some of the big points, but Kevin G did a great job of wrapping up this short video with a wealth of information. Here’s the snapshot:
Donor frame: KTM 250
Battery: Customized 126V/30S battery pack
Motor: QS 138/70H
Controller: 3shul CL700
Rivv’s Honda 450 Conversion
Endless-Sphere forum user “Rivv” lives in Quebec, eastern Canada. He hasn’t posted a video yet, but luckily he does take a lot of photos of his awesome conversion of a Honda 450 to electric.
Both versions use a QS motor that we’ve noticed is growing in popularity (for our article on QS motors click here). The thing that ties them all together is that they both use a 3shul Motors VESC, model CL700. This model seems to be the sweet spot between good size, good power and affordable price.
Just showing pictures of the controllers isn’t very exciting, since they’re pretty much a “black box” full of wizardry electronics. One of the things that caught my attention about Rivv’s remodel was the high quality build, and the great photos he took and posted.
QS announced that they will soon start carrying a larger size 180/90H motor model and will include a similar factory gear reduction to the smaller 165/70.
When Rivv built his mod, the big motor didn’t have a factory reduction option, so he decided to build a DIY reduction “intermediate shaft”. By reducing the output rpm, he will be able to use a common rear wheel sprocket to adjust the wheel speed for different conditions, rather than a custom large diameter sprocket with a direct chain from the motor to the wheel.
The image above shows a plastic 3D printed dry case made by Rivv to test the required size and shape before ordering the expensive CNC aluminum case.
This is a custom CNC aluminum gear housing, along with sprockets and chain. 17T and 11T sprockets provide a 1.54:1 reduction ratio
This is the motor, aluminum reduction jackshaft housing and plastic cover.
This is a top view of the midshaft. Rivv has a lathe and other machine tools in his workshop, and this build makes good use of them.
Not much to say about the QS motors and 3shul VESC, except that some very experienced people seem to like them, and I haven’t used them yet.
Most of the work I do is “crowdsourced” knowledge and I do a lot of reading. I keep seeing people mention using 3shul VESC controllers, so I’m happy to find some versions with pictures showing them.
The controller can be mounted anywhere, especially one that is packaged like this, which means the components inside are completely covered with a generous amount of waterproof goo, which also provides shock protection. Rivv mounted it upside down under the seat and added extra aluminum pads to help absorb heat spikes.
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 high current cylindrical Molicel P28A cells in 18650 format.
Rivv first draws everything in CAD
Even with a computer model, there’s no harm in using Cardboard Aided Design. Here, Rivv built a foam case to verify his battery case dimensions. For the last decade or so, most dirt bikes have used a “twin Spar” frame design, which made the switch easier for us electric builders. Older models had a single top tube, like a bike…which limited the shape and size of the battery.
The Rivvs program calls for a huge battery pack of 14 parallel cells (14P)
Rivv ordered these custom bus panels to be laser cut and they turned out great. Motorcycles draw high current and the copper bus has low resistance. Plus, they act as thermal sponges to balance out the heat from the amp’s spikes.
Here, Rivv is adding grooves to the aluminum panels that protect the battery compartment
This is one of the largest battery packs I’ve seen in a modding. It provides high voltage, high current and long distance.
By Ron/spinningmagnets, June 2023