John in CR wrote:
veloman wrote:Low speed efficiency may also be improved, the jury is still out on that. I do think I'm 1-2mph faster on hills with it though. Top speed is something I should test, but will also be higher once I go to a123 battery next week hopefully.
Efficiency during acceleration will definitely be improved with the slower wind.
Being faster going up the hills is the perfect evidence that the gearing is wrong on the 6T motor, so why don't they just put different gears in there? The question I tried to ask before is, are they already at some practical limit of the gearing reduction of these motors?
I would guess that using a different gearing in the motor would significantly increase costs. I think the goal with the different windings is to offer different top speeds, assuming the same voltage. Most people are getting the 10 or 12 turn if they are building a trail/off road hill climbing ebike.
When I first heard about the 6 turn, and it going 30mph on 36v, I thought "why not just get a DD then?"
My very first ebike I built was a brushed currie motor with no reduction, just a straight 1:6 chain drive ratio to the rear wheel (700c). That thing got hot very easily and had no balls on the hills/starts. No load speed was 46mph and I ran it at around 750watts on SLA. I didn't want to go 40mph on it, it was clear I would of been better off with gearing that let it top out at 30mph.
That's my situation now, I don't want to go 50mph, more like 40mph is acceptable (with 120% setting), though 95% of my riding is at 18-27mph.
So your thought is that you want the lowest turn count motor possible, and alter the gearing to match it best to your riding speeds? Is that the idea behind rc outrunners that spin 10k rpm?
I think working backward, basing your design on your top speed at your planned voltage is the way to go. For you, you want and need a low turn because you want 60mph and will feed it that power. 5kw on a low turn still will launch off the line and eat hills in most cases. But for me, I want to keep my wattage limited to 1200 or 1500w so I can keep reasonable range at ~22wh/mile. This statement may be flawed. I think some of you guys are suggesting to set it to high power like 2kw, and just use the speed switch to limit speed. (the one downside to this other than a slight decrease in efficiency is the extra wear on the Mac gears at 2kw.) I will be riding a123 very soon, so I will be able to put it at 40amps or 2kw.... (how long will 30amp andersons last at 40amps?) The thing is most of the time, I really only need about 800w to accelerate or 1000w to climb happily.
A current based throttle would fix that. Imagine driving a car with a speed throttle. 100% engine output at the slightest touch.....