Post
by The Toecutter » Jan 22 2023 3:53pm
You can't go wrong with a Phaserunner controller backed by a heat sink. 96A peak phase current, and can do 50A all day long. With my 4T motor, acceleration was more than adequate. 0-30 mph acceleration took me about 6 seconds when set for 3kW peak. This was a build made for 45-50 mph top end and the Phaserunner was able to handle it without too much issues(there were some, mainly relating to the XT60 connector it came with, but I also ran it without a heat sink.). You're only seeking 30 mph, which is easy to design for, and I'm certain the controller I mention could handle your needs, especially if it is attached to a small heat sink.
You should also build a body around it.
In the summer, as long as I'm moving, having a shell is actually cooler than without a shell, even on 90F+ days, and is a lot more comfortable in cold winter riding as well because I heat up pedaling and don't lose the built-up warmth. It is only in high temperature weather that when stopped or climbing a steep hill with no electric assist that I cook, and it is brutal when it happens. But with a motor, I can sustain speeds that provide excellent cooling with low effort because the motor is providing most of the thrust, even going up steep hills. My electric velo didn't have cooling anywhere near as good as my unmotorized Milan, either, and the Milan was actually more comfortable at 30 mph cruising than my electric corovelo as a result(again, stops and steep hill climbs are brutal in the Milan, and I cannot emphasize this enough, but a motor would have changed that). You could easily make that Performer have better cooling than the Milan because aero was the Milan's defining focus and its existing cooling is the result of seeking drag reduction. In your case you could probably cut the drag to about 1/4 of what the Performer currently is unfared and maybe have 3x the Milan's drag while having wonderful cooling for summer riding plus constant shade carried with you. Without suspension clearances to worry about, it would be much easier to design a shell for your Performer than it was to design a shell for my KMX with suspension. With the motor providing most of the thrust, even steep hillclimbs could have you holding 30 mph, which will keep you from overheating or having to exert yourself to where you build up so much heat that stops make the vehicle an oven.
Then it would also provide some rain protection. And increased visibility to any motorists actually looking at the road. And depending upon design, possibly some collision protection against heavier vehicles.
A body designed to CdA < 0.12 m^2 plus some Continental Contact Urban tires with a Crr ~0.005 at 75PSI, could have you only needing 5-6 Wh/mile @ 30 mph on flat ground with 100W pedaling effort. You could shrink your battery pack accordingly to improve acceleration and cut weight for riding unassisted, or enjoy greatly increased range. Plus the shell can increase your storage space well beyond the capabilities of panniers, making it a more practical vehicle on the whole, which is the idea behind replacing a car.
It doesn't have to be a complicated body to achieve this, either. The Australian Pedal Prix racers are a gold mine of ideas for a quick and dirty coroplast faring with aerodynamics comparable to what I described above.
As a bonus, the reduced drag from a body would allow your controller to cool off because your pedaling effort accounts for a greatly more significant portion of the motive force than it would unfared.
