Driver interface to controller

#1

We need to be thinking about the driver interface method for the technology. I have some thoughts on the subject to get this started. Please share, contribute and (constructively) critique your fellow contributors.

I suggest a simple wand that attaches to the shifter on the vehicle. Instead of interfacing to the existing pedal/brake system and worrying about all the details of the existing ICE (internal combustion engine) controls in various vehicles, we develop an entirely independent system and depend on the educated driver to use the controls appropriately. Push forward on the little wand to go forward, pull back to engage regenerative breaking, leave in spring loaded neutral position when operating as a conventional vehicle. If the vehicle has a standard transmission, the operator will be running in neutral and it will be natural to control from that point. For an auto tranny car conversion we are going to have problems with torque converter/transmission damage if the user drives without the engine idling - so dealing with that will complicate those conversions. I therefore suggest a simple early path to operation pursuing smaller standard transmission front wheel drive cars and a simple generic interface able to work on many car types.

Now ought we create and document what we think is an appropriate hardware set for the motor controller people to consider as they work through those technical details?

#2

I agree the easiest way to implement a hybrid system is to do so with FWD manual transmission cars. A secondary advantage to this is these cars are plentiful, usually affordable, and many are lightweight and sporty so it may make for a fun driving experience if converted properly.

One idea for a rudimentary hybrid drive system is a position sensor/potentiometer mounted onto the existing accelerator pedal to read pedal position and transmit that to the electric drive. This would allow for operation of both the gas motor and the electric motors as a hybrid system without requiring you to intercept the digital signal in modern “throttle-by-wire” cars. It would also work in older cars that use a mechanical throttle linkage. The “throttle mapping” could be done with mechanical gearing between the pedal and your chosen position sensor.

The downside to this is if you wanted to run “pure electric” to drive the car but have the transmission in neutral and engine running to power accessories, power steering, braking, etc, you’d be revving the engine all the time. You could get around this with a redundant input method (like the previously described throttle lever) to use if you don’t want driving power from the gas motor.

With an ideal version of this system you’d be able to keep power coming from the electric motors even while shifting gears for the gas motor. If the electric throttle is linked mechanically to the gas pedal this wouldn’t be possible, although I don’t think it would differ much in “experience” from driving the typical non-hybrid version of the car…

#3

Hey there,
Hybrid systems are definately thinkable, though efficiency drops as you drag along all the combustion equipment.

With fully analog cars implementing a potentiometer along your accelerator should be the way. For modern drive by wire cars its enough to sniff the can messages associated for the accelerator pedal and feed them to the motor controller.

With hybrid setups, to overcome having a idling combustionmotor just to operate breakboosters etc., it is feasible to install a simple 12v vacuum pump instead of the belt driven versions.

#4

I saw your comment in the other post about Mini Cooper stuff, had no idea it could be that easy to catch the signal from a drive by wire pedal. I’m just getting up to speed on this project and DIY EVs in general. Thanks for being so responsive it’s great to see there’s life on this project!

My interest in this project is definitely to build a hybrid. I have an EV already, and a road bicycle, and building an e-bike, and live where public transit is OK, so my car for this project is my third or fourth option for getting around. Before I started caring about this stuff I came from a performance driving/sports cars background. I’d like to see what kind of attention DIY EVs can get from people in that crowd and unfortunately most traditional car enthusiasts are hard to reach about the benefits of EVs. I feel adding a non-invasive power boost like hub motors to the rear wheels of an already very fun car might get enthusiasts thinking differently about electrification. Taking a 230 hp fwd car and turning it into a 330hp awd hybrid while adding barely the weight of a passenger would be fun no-doubt. Plus having even 20 miles pure electric range would more than suit my needs for the vehicle.

I hope this perspective is welcome here, I have been dreaming about this type of build for years so it’s encouraging to see an open source community around it! There is a tremendous amount of activity in performance modifications, capturing even a fraction of that effort would be a great boost to building EVs in my mind. Sorry to go off topic…

#5

All perspectives are welcome :slight_smile:

But in terms of powerboost, that one is to be validated. Hubmotors are ungeared, which means torque is generally not where they accel. So i would say don’t expect Tesla-style performance for hubmotor driven systems. The motordesign can and we plan to do so, be modified to be a “normal” middlemotor which you can bolt onto your gearbox, much like most conversions are done today. Building a hybrid that way would be difficult.
If you want to go the hybrid route though, and want performance you should check out Damien Maguire’s work on Lexus Hybrid Gearboxes https://www.youtube.com/watch?v=gh-nTtw7k6U