modern_messiah
100 W
Hi all,
I posted this on another forum, but this place seems to have a larger appetite for innovation so figure I should at least ask here as well
This is a potential project that for now is just an idea to flesh out a bit more rather than something I’d definitely do.
I have a FWD car that is also available in an AWD variant. Simply selling and upgrading to the AWD variant, while probably much easier, is not an option because it’s boring to me. Plus I’m an engineer and this sort of project would be insanely fun and satisfying to me.
My idea is to swap some parts between the two models to provide a way for me to interface electric motors with the rear wheels. The goal is not for fuel efficiency purposes; I simply want to help my car accelerate faster.
I am inquiring elsewhere about what suspension and drive-train componentry is required to be swapped between cars (should be direct swap and bolt on which is nice), however in essence the diff will be replaced by 2 electric motors which will interface with the rear axles. The battery pack and controllers will reside in the boot.
I am unsure about what sort of power figures I need, let alone the hardware to meet my requirements, so I’ll give a small break down of what I want the system to do and go from there:
> The car already does 0-100kmh (0-62mph) in approximately 6 seconds
> My plan is for the motors to assist with acceleration, but only when the cars main combustion engine is under 4500rpm and the throttle is at least 80% open.
> I’d also not expect the motors to be needed when the main drive train is running in gears 4, 5 and 6. The reason being that wheel slip will not be an issue at those speeds.
> Basically the rear motors are only running when I’m accelerating hard from a standstill or low initial speeds.
> All other times the motors are doing nothing apart from regenerative braking, which is only needed until the batteries are fully charged again.
> The battery pack can likely be quite small as well. Given the car is not reliant on these motors at all, a flat pack wouldn’t leave me stuck anywhere.
How I’ll get the motor controllers to function in the above manner is yet to be determined, but I can interface to my cars CANBUS via a Bluetooth dongle easily enough. I just need an intermediary device to read the CANBUS data and then automatically operate the controllers appropriately. Initially however I’ll simply have an electronic throttle controller mounted somewhere in the front of the car and worry about the automation later on.
I don’t need stupid power. Given the instant nature of the torque provided by electric motors, they tend to punch well above their apparent power rating. I’m thinking between 15 and 20kW per motor would make a noticeable difference. Those are peak ratings too as I’ll likely never run them flat out for more than a few seconds.
What are people’s thoughts? Brain dead stupid or something that would work, but more importantly be worthwhile?
If it’s the latter, what sort of motors should I be looking at? Matching controllers? Would gear reduction be necessary/recommended? What have I not thought of or stupidly overlooked? Why can’t/shouldn’t this be done?
I’m not even worrying about prices yet; as I said I’m just fleshing this idea out a bit more from the current “bored on the loo phase” lol.
Thanks for reading!
- Matt
I posted this on another forum, but this place seems to have a larger appetite for innovation so figure I should at least ask here as well
This is a potential project that for now is just an idea to flesh out a bit more rather than something I’d definitely do.
I have a FWD car that is also available in an AWD variant. Simply selling and upgrading to the AWD variant, while probably much easier, is not an option because it’s boring to me. Plus I’m an engineer and this sort of project would be insanely fun and satisfying to me.
My idea is to swap some parts between the two models to provide a way for me to interface electric motors with the rear wheels. The goal is not for fuel efficiency purposes; I simply want to help my car accelerate faster.
I am inquiring elsewhere about what suspension and drive-train componentry is required to be swapped between cars (should be direct swap and bolt on which is nice), however in essence the diff will be replaced by 2 electric motors which will interface with the rear axles. The battery pack and controllers will reside in the boot.
I am unsure about what sort of power figures I need, let alone the hardware to meet my requirements, so I’ll give a small break down of what I want the system to do and go from there:
> The car already does 0-100kmh (0-62mph) in approximately 6 seconds
> My plan is for the motors to assist with acceleration, but only when the cars main combustion engine is under 4500rpm and the throttle is at least 80% open.
> I’d also not expect the motors to be needed when the main drive train is running in gears 4, 5 and 6. The reason being that wheel slip will not be an issue at those speeds.
> Basically the rear motors are only running when I’m accelerating hard from a standstill or low initial speeds.
> All other times the motors are doing nothing apart from regenerative braking, which is only needed until the batteries are fully charged again.
> The battery pack can likely be quite small as well. Given the car is not reliant on these motors at all, a flat pack wouldn’t leave me stuck anywhere.
How I’ll get the motor controllers to function in the above manner is yet to be determined, but I can interface to my cars CANBUS via a Bluetooth dongle easily enough. I just need an intermediary device to read the CANBUS data and then automatically operate the controllers appropriately. Initially however I’ll simply have an electronic throttle controller mounted somewhere in the front of the car and worry about the automation later on.
I don’t need stupid power. Given the instant nature of the torque provided by electric motors, they tend to punch well above their apparent power rating. I’m thinking between 15 and 20kW per motor would make a noticeable difference. Those are peak ratings too as I’ll likely never run them flat out for more than a few seconds.
What are people’s thoughts? Brain dead stupid or something that would work, but more importantly be worthwhile?
If it’s the latter, what sort of motors should I be looking at? Matching controllers? Would gear reduction be necessary/recommended? What have I not thought of or stupidly overlooked? Why can’t/shouldn’t this be done?
I’m not even worrying about prices yet; as I said I’m just fleshing this idea out a bit more from the current “bored on the loo phase” lol.
Thanks for reading!
- Matt