Hi!
I am going to be converting an mx-5 using a 160kW leaf stack. The idea is to put it all in the rear subframe and go straight to the wheels using the leaf gearbox. According to my calculations this would mean a top speed of around 130kph at 10k rpm.
I want to use the full potential of the motor, but I also want to keep the weight down. 6 or possibly 5 ID.3 modules is what I am thinking of using(72 or 60s). However, I am afraid this would limit the performance, especially at high rpm due to back emf?
Other options would be a full e-Up or e-Golf pack, but I'm also not sure how much power they can deliver. For the BMS I would like to use the OEM slaves with something like the engovis bms, which is why I'm looking at these VW packs.
I'd be happy to hear your thoughts
160kW leaf performance at low voltage
Re: 160kW leaf performance at low voltage
Myself and others have been trying to fit the Leaf motor in the rear subframe, in my case using CAD models so far, but it doesn't seem possible while keeping the stock suspension hard points. I agree it's a nice idea and if you find a way, please let me know.
With regards to voltage, you're looking at 3/4 of the Leaf pack voltage (96S 2P). That's quite a drop which I think you would see as an associated drop in power and max RPM. Others can give a more educated answer on the numbers, but I would guess you'd be looking at 120kW and 8000RPM redline (I'm assuming a linear association with voltage. Could be wrong...)
Chris
With regards to voltage, you're looking at 3/4 of the Leaf pack voltage (96S 2P). That's quite a drop which I think you would see as an associated drop in power and max RPM. Others can give a more educated answer on the numbers, but I would guess you'd be looking at 120kW and 8000RPM redline (I'm assuming a linear association with voltage. Could be wrong...)
Chris
Re: 160kW leaf performance at low voltage
Pete's IPM motor simulator software can give an accurate estimation of the performance envelope at that voltage, although I haven't seen him around lately and don't know if the project is still being maintained.
I had similar questions at the start of my build though and from what I gathered and what I simulated, yeah you will be down on power by a roughly proportional amount. Not only that, but the speed at which the torque begins to drop (going into the constant powet region) will also be proportionally lower.
Redline could theoretically be the same but since the torque will be lower, the achievable top speed will be lower. To work out how much lower, you would have to do some calculations to estimate the power needed to overcome aerodynamic drag at a given speed and then check whether the motor is expected to be capable of producing enough power at the corresponding rpm.
If I were personally looking to do this I'd probably be having a close look at fitting a BMW hybrid battery. I don't think I would trust the 9 or 12kwh packs to output 160kw reliably, but perhaps the larger 24kwh from the X5 might work? The good news is the individual modules are relatively small so potentially easier to arrange to fit in the car. The BMS could be reused if you use the right hardware to communicate with it. The challenges will be cooling the modules, and fitting a proper enclosure (assuming you wanted to take the car to any kind of track or racing event).
I had similar questions at the start of my build though and from what I gathered and what I simulated, yeah you will be down on power by a roughly proportional amount. Not only that, but the speed at which the torque begins to drop (going into the constant powet region) will also be proportionally lower.
Redline could theoretically be the same but since the torque will be lower, the achievable top speed will be lower. To work out how much lower, you would have to do some calculations to estimate the power needed to overcome aerodynamic drag at a given speed and then check whether the motor is expected to be capable of producing enough power at the corresponding rpm.
If I were personally looking to do this I'd probably be having a close look at fitting a BMW hybrid battery. I don't think I would trust the 9 or 12kwh packs to output 160kw reliably, but perhaps the larger 24kwh from the X5 might work? The good news is the individual modules are relatively small so potentially easier to arrange to fit in the car. The BMS could be reused if you use the right hardware to communicate with it. The challenges will be cooling the modules, and fitting a proper enclosure (assuming you wanted to take the car to any kind of track or racing event).
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arber333
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Re: 160kW leaf performance at low voltage
I have tested EM61 motor on Mazda RX8 transmission with 80S and it performs great! For control we used Chevy Volt inverter and Lebowski board. I replaced resolver with RLS commutation sensor UVW for signals. Just before start it is a bit shaky but motor would provide great torque from drive-off.
I think using OEM inverter you are limited to OEM voltage limits. This means about 280Vdc would still be OK-ish... but not much less. I would say 80S is your lower limit if you dont want to replace control section...
On the other hand it seems Chevy Volt inverter can work down to 60Vdc you just need to replace its brain...
I think using OEM inverter you are limited to OEM voltage limits. This means about 280Vdc would still be OK-ish... but not much less. I would say 80S is your lower limit if you dont want to replace control section...
On the other hand it seems Chevy Volt inverter can work down to 60Vdc you just need to replace its brain...