Frank
100 W
This looks great!
Warren said:Thanks for the new video. All the talk of endless electric SUVs coming soon, makes me depressed. This is the most hopeful thing I have seen since the pandemic started. Stay well, and all the best.
Actually the Electrom is pretty good off-road. Of course it would suck to crash it and damage the bodywork.I'm looking to make an off-road recumbent soon, so this wouldn't really work for that.
As long as we are talking about experience, I should let you know that while I didn't join Endless Sphere until 2015, I was referencing it and other sites from the beginning, and I do mean The Beginning; I built my first electric assist recumbent in 1998 and started working on the predecessor to the Electrom in 2003. I've worked in bikeshops my whole life and owned and operated a mountain bike shop for 10 years from 1992 to 2002I have operated both of these motors in 20 inch wheels and my opinion comes from many years of experience.
I'm not sure you have fully considered the parameters I am looking for. As I am building a street legal machine for sale to the general public, High starting torque for hill climbing and starting out is far more important to me that high speed efficiencies. The top legal speed for an ebike here in BC is 32 kph, the top legal speed for an ebike in California is 28 mph. The Golden Magic Pie is efficient enough at 72 volts in these speed ranges. An efficiency difference of 5% is not enough to outweigh the other advantage is this wheel.Yes, the 273mm stator has amazing initial torque but peters out in the mid-high RPM ranges and loses efficiency to iron and copper losses. You'll see it in the ebikes.ca simulator and i have experienced it in real life running 48-125v in a 20 inch wheel.
This is even noticeable at 48v.
This is just an inherent nature of the motor dimensions themselves.
Again, my machine needs to operate within the bicycle legal power parameters, simply upping the power is not always an option. When it comes to Direct Drive motors it is a question of simple leverage, the biggest stator in the smallest rim is going to yield the best starting torque.Impressive low RPM torque is absolutely available from the 9C type motors. No problem. Set an appropriate phase amp to battery amp ratio and you are good to go.
I don't think you really read my previous response. The double stage gear reduction in the G311 yields more torque per watt than a single stage reduction, which allows for hill climbing power within the legal power limits. The motor shuts down at 30 kph to save power and it has the added benefit of not challenging the magnet adhesion (BTW, this is one of the motors that Grin re-glued the magnets on). I do concede that this motor will not be used in production because it has proven to be unreliable at high RPMs and I have no control over the setting once the bike is in the customer's hands.Okay, you have eliminated a mechanical motor limitation with electronics but there are still better motors for your front wheel which have higher efficiency.
AWD is not the same on a two-wheel vehicle as it is on a car. It would not do much for you in a slippery situation over 30 kph. It is true that a higher power bike might inadvertently spin the back wheel at high speed, but in this case adhering to the bicycle power limits makes this unlikely. If the best efficiency per motor is around 85%, why would waste 15% running a motor that is unneeded at cruising speed.Unfortunately the difference in winding between your two motors prevents torque full time vectoring AWD from being part of your design. AWD can be an excellent safety feature for a vehicle. Having a safety feature be intermittently available is a shame.
Absolutely, I'd be a fool to post here if I was not going to consider the opinions offered. I will say that with the extra torque of the front geared hub motor I am tempted to go with a lighter DD rear motor, but I do really like the heavy duty build of the Magi Pie. I will also be trying out the GMAC hub motor on the rear as it has amazing re-gen braking.I've stated my case and i hope you at least consider it.
Your vehicle is impressive to me and i am watching your thread closely to glean experience from what you are doing, as i am building a bike in a similar vein.
tigcross said:Thanks, I appreciate your input. I've checked out your Maxaraya build and I'll try to get some of my initial thoughts down for you.
tigcross said:I'm thinking that my best combination of start-up-torque and high-speed-efficiency would come from a smaller stator DD rear wheel, and a decent geared hub motor that shuts down above a certain speed. This way we eliminate the losses from a 2nd motor at high speed, but still have that geared-motor torque available start up and hill climbing.
Actually I'm using the External Controller version of the Magic Pie with a Grinfineon 40 amp, 72 volt controller (I guess I should have clarified that somewhere).Isn't your start up torque limited immensely just by the low (phase)current that the Magic Pie internal controller can provide?