Was just browsing around the various online motor sources I look at every once in a while and noticed this one I haven't seen before now available at hobby king:
http://www.hobbyking.com/hobbyking/...y_9014_105kv_Brushless_Multi_Rotor_Motor.html
It's a 9014 (90mm diameter, 14mm thickness) pancake motor designed to run off a 6-cell Li-Poly pack at 40A rated for 900watts. Out-runner, obviously. For a non-scorcher e-bike mid-drive jackshaft build that's a good amount of power in a nice thin package that would easily fit in the frame triangle and even with a set of twin mounting bearings, one on each side, with a short shaft through its core would still be no wider then the frame width of the bicycle, at least for a MTB frame with its larger tube size but would probably by a nice thin package in the frame triangle even in a road bike. Kv rating is 105 which is nice and low like we like them for RC e-bike builds so at 22.2V under load voltage from a 6-cell pack no-load free running RPMs would be 2,331 and the peak power RPM assuming typical power curve would thus be about 1,500 RPM or so. That's only about a 5:1 reduction to a jack-shaft with a smallish 14-tooth or so output sprocket which is possible in only a single stage using standard bicycle chain using a standard three way jackshaft mid-drive system with the stub-shaft being the center of a three chain loops (output chain to rear wheel and rear gears, input chain from motor, input chain from pedal crank). Would be a two stage reduction to skip the jackshaft and hook the motor directly into a freewheeling crank. If your not looking to run the motor through the gears could also just run straight back to the rear wheel with a big over-size 60 some tooth sprocket on the rear wheel and a 13 tooth drive sprocket on the motor.
Of course I wouldn't need quite those reduction levels since I'd run it on a 12.8V 4-cell LiFePO4 prismatic pack at lower power levels. I've done several 12.8V low voltage builds so far and they rock for being able to run LED automobile lights directly off the main pack for great cheap very bright lighting options and also I can charge the battery anywhere I can get my hands on a regular 12V car battery charger set to low charge rate. Finding appropriate motors and controllers that are compatible with them and will work for my needs, being the main problem with going that low on the voltage. Last build that I went that low on the voltage I used a 6354 designed to run off of 4-to-6 cells Li-Poly and then had to install my own hall sensors following the instructions of a scooter guy (he makes those little folding side-walk mini-scooters really move) that posted online his process of adding hall sensors to a 6374 and then used a 12-to-24V Kelly 50A controller that accepted standard e-bike throttle units. I don't think adding hall sensors would work so well with this thin pancake motor and even if it could be done I wouldn't no how to go about it (following directions with pictures for a 6374 on a 6354 I could figure out by just copying and adjusting for my shorter can length but this motor is a whole different animal altogether) so I would probably have to go RC brushless, sensorless controller on this one and rig a throttle interface for the RC motor controller.
Anyone know of a sensorless e-bike controller that will work with 12V low voltage (programmable like a Kelly would be really nice but probably asking way too much since I would probably be lucky to even find one that will go that low on the voltage much less anything else)? Anyone have any general thoughts about using this kind of thin pancake RC motor for a mid-drive build keeping nice and thin and staying within the width of the frame triangle?
http://www.hobbyking.com/hobbyking/...y_9014_105kv_Brushless_Multi_Rotor_Motor.html
It's a 9014 (90mm diameter, 14mm thickness) pancake motor designed to run off a 6-cell Li-Poly pack at 40A rated for 900watts. Out-runner, obviously. For a non-scorcher e-bike mid-drive jackshaft build that's a good amount of power in a nice thin package that would easily fit in the frame triangle and even with a set of twin mounting bearings, one on each side, with a short shaft through its core would still be no wider then the frame width of the bicycle, at least for a MTB frame with its larger tube size but would probably by a nice thin package in the frame triangle even in a road bike. Kv rating is 105 which is nice and low like we like them for RC e-bike builds so at 22.2V under load voltage from a 6-cell pack no-load free running RPMs would be 2,331 and the peak power RPM assuming typical power curve would thus be about 1,500 RPM or so. That's only about a 5:1 reduction to a jack-shaft with a smallish 14-tooth or so output sprocket which is possible in only a single stage using standard bicycle chain using a standard three way jackshaft mid-drive system with the stub-shaft being the center of a three chain loops (output chain to rear wheel and rear gears, input chain from motor, input chain from pedal crank). Would be a two stage reduction to skip the jackshaft and hook the motor directly into a freewheeling crank. If your not looking to run the motor through the gears could also just run straight back to the rear wheel with a big over-size 60 some tooth sprocket on the rear wheel and a 13 tooth drive sprocket on the motor.
Of course I wouldn't need quite those reduction levels since I'd run it on a 12.8V 4-cell LiFePO4 prismatic pack at lower power levels. I've done several 12.8V low voltage builds so far and they rock for being able to run LED automobile lights directly off the main pack for great cheap very bright lighting options and also I can charge the battery anywhere I can get my hands on a regular 12V car battery charger set to low charge rate. Finding appropriate motors and controllers that are compatible with them and will work for my needs, being the main problem with going that low on the voltage. Last build that I went that low on the voltage I used a 6354 designed to run off of 4-to-6 cells Li-Poly and then had to install my own hall sensors following the instructions of a scooter guy (he makes those little folding side-walk mini-scooters really move) that posted online his process of adding hall sensors to a 6374 and then used a 12-to-24V Kelly 50A controller that accepted standard e-bike throttle units. I don't think adding hall sensors would work so well with this thin pancake motor and even if it could be done I wouldn't no how to go about it (following directions with pictures for a 6374 on a 6354 I could figure out by just copying and adjusting for my shorter can length but this motor is a whole different animal altogether) so I would probably have to go RC brushless, sensorless controller on this one and rig a throttle interface for the RC motor controller.
Anyone know of a sensorless e-bike controller that will work with 12V low voltage (programmable like a Kelly would be really nice but probably asking way too much since I would probably be lucky to even find one that will go that low on the voltage much less anything else)? Anyone have any general thoughts about using this kind of thin pancake RC motor for a mid-drive build keeping nice and thin and staying within the width of the frame triangle?
