Electric Motocross Project
The new generation batteries that make the BMW project so potent has excellent potential for two wheel applications as well.
This project is intended to demonstrate this potential by conversion of full performance race ready Honda CRF250R's to race ready full performance electric(CRF2eR) with equal or better performance.
Imagine how this quiet machine could change the riding opportunities. Neighbors will no longer even know you are riding. The tracks around the country that have closed because of noise would be able to continue with full electric motocrossers. When trail riding, you literally see more activity from "sneaking up" on wildlife as well as minimizing your impact.
The rewards from conversion verses ground up design are significant. We are starting with a known package that any CRF rider would immediately feel comfortable with and can withstand the pounding of the most brutal motocross tracks. This is accomplished by matching the weight and weight distribution of the original gas powered design and building the electric drive system with equal or greater tolerance to normal "abuse" by pro riders on the track.
Updates are appended to the bottom of this page
Click on images to view full size
October 2007
The CRF250R to CRF2eR conversion is being developed simultaneously with the BMW project because they share the same battery management design as well as being the initial test platform. This off road application demands 50% higher peak currents than the BMW electric system. The general design is scaleable to any cell size and cell count to accommodate different motors, controllers and storage capacity.
Two fresh CRF250R bikes...
The motor is out in no time
The rolling chassis ready for electrifying
Drive system is complete. Battery packaging and mounting is nearing completion.
Road testing was planned for January 08, but is looking more like February.
Working the Alu billet on the lathe:
Prototype battery boxes being constructed
There was some extra work needed to get the new battery cell welder running...
Three phase power is needed which means creating it from single phase power.
Here is the unit I wired up to convert Single phase 240VAC to 3 Phase 240VAC.
It is a rotary converter that uses 240VAC to spin this idle motor while having 3 phase taps.
A milestone reached Saturday February 2nd: First welded packs take form:
Cell welding begins
The last plate of the first pack is ready to place and weld:
Here is the first pack with full current path welded. These packs can deliver nearly 1000 Amps as specified from the cell manufacturer. This will never limit the power delivery since the motor drive system can only draw 600 Amps peak!
This portion of the power package goes into the location of the original air intake box. It's battery management circuit will be placed in the space above the cells along with a large fuse and 600 Amp cable headers before being covered.
We did no welding or drilling to the original Alu chassis; here we are welding the frame mounts to our new down tubes. All pieces simply bolt on with captive nuts everywhere.
The complete set of components fabricated for this prototype ready for final assembly along with the motor and control system... The results of two months of design and fab:
A dyno test is planned for a side by side comparison between the original gas powered CRF250R machine and this new electric CRF2eR. The performance curves will be overlaid .....Stay tuned...
We will first need to work out the controller settings for best power delivery as well as the charging system details.
Today a milestone was reached in the project; the real world testing has begun!
But first, here are some shots of the final assembly from the previous days...
The chassis with some of our new components bolted in place.
Here is where the 3rd of three packs go. All packs are designed to fit inside various original spaces to allow all outside surfaces to remain unchanged.
The upper battery box drops right in. We are adding 4 pounds of copper wire to deliver the 600 Amp peak currents.
The bike is just about ready to roll....
Hyper throttle..there was some adjustment needed
The finished package, minus side panels
View from the rear
side by side
The first dry dirt testing and what an awesome result..
March 08 2008 update:
The new look, complete with side panels
Also, Electric MX and related topics discussed in detail
May 2008 update:
We are very focused on two near term goals:
1. The BMS turn on and installation. There is a bit of software work remaining.
2. Replication of the machine with CNC mfg means. We are working on a 2nd build to fully evaluate the complete package.
August 2008 update:
Parts are ariving for the 2nd version/build of our CRF2eR from 3rd party vendors that replicated our design with CNC machining.
We have dropped the weight and improved the drive system with custom splined shafts that are much lighter but very capable of handling the full power/torque transfered to the rear wheel, just as the stock sprockets do.
Here is the CAD view of our new drive system mounting plates:
A couple sets of the mounting hardware
September 08 update:
This new custom splined shaft allows the use of off-the-shelf sprockets that are light and inexpensive. Assembly just got a lot easier too.
Here is the chassis before installion of the motor controllers, cells and wiring
This bike has street tires for hitting the dyno at the next opportunity and some asphalt testing...
The BMS electronics and software are nearing completion that will be added to this chassis for full range testing.
Also in progress: a custom 2kW charger that will obtain a full charge in 40 minutes.
