Quote:
Originally Posted by Ecky
After playing with GRIN's motor simulator, I'm thinking the difference in efficiency won't be nearly so large as you're predicting. It appears that the MAC will actually have an edge in efficiency while getting up to speed, and in some hill-climb scenarios, while the Leaf motor pulls ahead in cruise, but only slightly. I'll get regen braking with the Leaf motor, which may make up for the difference in efficiency in a stop and go "city" drive cycle.
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Interesting. I didn't run a simulation with this tool with your parameters and was taking a guess based on earlier simulations I did using this tool where I used parameters suited for my requirements when I was initially considering a MAC(I was going for fastest overall 0-30 mph acceleration time possible with the controller I planned to use, while allowing a 50 mph top speed, which at 30 mph cruise, greatly hurt efficiency). The increased thermal efficiency for your parameters versus what I assumed they would be makes a big difference. However, I am curious if that simulator factors in losses from the composite gears, or just spits out the motor's efficiency by itself based on what it is calculated to be?
So based on your simulation's parameters for 30 mph, 83% eff for the MAC, 87% for the Leaf. Your preliminary 21 wh/mi at 30 mph figure is drawing 630W from your pack. At an assumed 5% electrical losses in non-motor parts(controller, wiring, ect), assuming 83% efficiency for the MAC, we get 497W at the wheels to move at speed. The Leaf motor at 87% efficiency should lower the power from the battery pack to 601W or reduce your energy consumption at a steady 30 mph by 1 Wh/mile, using the same methodology that I used earlier to estimate a larger difference between the two.
1 Wh/mi is still noticeable. There's a lot more to be gained by working on the aerodynamics though.
The simulator seems to be over-estimating your power requirements when comparing with your preliminary data, but then again your vehicle's actual CdA/Crr parameters are still unknowns and that will modify the simulator's performance, temperature, and range calculations in an undesired direction versus the real results.
I think the regen will be a huge asset in stop and go city driving or for reclaiming range while going down long hills when not wanting to exceed the speed limit.
Please, get some videos showing us your acceleration, and have a speedometer of some sort in the video as well when you do it so we can see it climb up in speed!
I think 0-30 mph in under 7 seconds is easily within reach right away for you with the Leafbike motor(and much faster is possible later). You will want to modify the dropouts with torque arms before you abuse them too much. These motors(as well as your MAC) can twist them, and then you're in the market for another trike, so be careful.