The E-Vox, A new ebike desing with belt for people 50+
- Thread starter Doctorbass
- Start date
liveforphysics
100 TW
For perspective, deathbike makes a real 640ft-lbs of torque to the rear wheel right now, and it's like instant-human-mutilating torque on a very extended swing-arm bicycle, and that's only ~860Nm.
I can assure you it would not be possible for that belt drive/pulley, nor that wheel, nor that chassis, nor that tire is capable of handling anything like 1000Nm or torque, and I may be the one of the few folks with the dyno-tested experience to conclusively make that statement.
IMHO, these guys are total morons for adding so much waste and management complexity, BMS cost, and increased safety and weatherproofing hassles to use such an inappropriate voltage for such piddly power levels.
For any ebike under 2kW, I personally would run 24v or less. When you only need to get power like 1ft from the battery to controller and another 1-2ft to motor, just using $3 of 8awg is orders of magnitude cheaper than adding a rats-nest of BMS wiring and expense and all the safety and weather-proofing BS that goes along with higher voltage.
I get it that if you have to make do with some off-the-shelf motor option that requires higher voltage to work well, but if you're doing a production product, it's not hard to get something wound with however many turns you like.
The trend of high-voltage stuff is so illogical, even from a hot-roding focused perspective.
I can assure you it would not be possible for that belt drive/pulley, nor that wheel, nor that chassis, nor that tire is capable of handling anything like 1000Nm or torque, and I may be the one of the few folks with the dyno-tested experience to conclusively make that statement.
IMHO, these guys are total morons for adding so much waste and management complexity, BMS cost, and increased safety and weatherproofing hassles to use such an inappropriate voltage for such piddly power levels.
For any ebike under 2kW, I personally would run 24v or less. When you only need to get power like 1ft from the battery to controller and another 1-2ft to motor, just using $3 of 8awg is orders of magnitude cheaper than adding a rats-nest of BMS wiring and expense and all the safety and weather-proofing BS that goes along with higher voltage.
I get it that if you have to make do with some off-the-shelf motor option that requires higher voltage to work well, but if you're doing a production product, it's not hard to get something wound with however many turns you like.
The trend of high-voltage stuff is so illogical, even from a hot-roding focused perspective.
Wishes
1 kW
Obviously the 1000 Nm must be a typo and he must have meant 100 or something. But I also don't get the 96v 2.5 amp approach. Whats the advantage except much higher costs in electronics to manage all those cells.
Wishes
Wishes
liveforphysics
100 TW
Wishes said:
There is no advantage and dozens of real disadvantages.
John in CR
100 TW
A lot of motors can't be wound to a high enough Kv to go to low voltage, at least for hubbies that's true. For those which can it may push the motor's inductance so low that controllers can handle it. One of mine has a Kv of between 16 and 17rpm/volt and the stator teeth have only 1.5 turns of copper. Controllers run away with their tails between their legs when asked to properly feed that beast. If it wasn't for these limitations I would certainly run my bikes at 3.7V nominal and accept whatever size copper is needed. Imagine no BMS needed and no risk of out of balance or over-charging.
spinningmagnets
100 TW
I was looking at the Evox patents (thanks for posting those, Miles), and there were several configurations that they seem to be wanting to get a piece of. One of them has a primary belt, a jackshaft, and a chain to the rear wheel. And another has a chain going to the right side so the motor has the use of the bikes gears.
These bikes are listed as very expensive, so I don't expect to see many of them on the road. However, they clearly knew that spinning a reasonably small motor faster and then reducing it down more was an option, and they clearly knew that giving the motor the use of the bikes gears would be a benefit, so...the configuration that is actually being sold to the public is puzzling.
The Euro-spec is 250W using 2.5A (one dealer in France), the Canadian version is 500W / 5A (not that 5A is a huge improvement).
____________________________________________________________________________
Here's the patent pic of the production version. The brushless DC permanent-magnet radial-flux rotor is directly connected to the small drive pulley. The pedal-axle is completely independent of the motor, and the fixed motor-shell and stator are bolted to the bikes frame. The rotor in the motor turns at only 1/4th the RPMs of the wheel...a terrible waste of an opportunity.
The numbers are upside-down, but this is from the orientation of the rider in the seat looking down at the motor. The Poly-V pulley is on the left, chainring not shown.
This configuration is in the patent, I don't know how much of it they can actually own and enforce. The motor has a belted reduction on the left to a jackshaft, and the right side chain presumably uses the bikes gears in a dual parallel right-side drive (like RWPs eCortina). The low-torque primary reduction may have actually worked well with a Poly-V belt (we'll never know), but the version they didn't use has a toothed belt, and the single-stage production version doesn't (whaaaat...huh? thats backwards)
As I see it:
Good:
Motor weight is central
Rear tire is light and no increase of flats or broken spokes, flats remain easy to fix
Gearless motor + belt-drive is very quiet
Battery mass and weight are in perfect location
Bad:
Price is unusually high, especially for low power and no suspension at all
Proprietary parts cannot be upgraded with 3rd party units, or repaired.
(custom Kv motor, ultra high voltage battery, ultra low amperage controller)
lots of custom engineering just to end up with a one-speed motor for a 250W/500W system.
no front disc brake, but does have mounts for aftermarket bolt-on.
Poly-V belt system means no possibility to hot rod for extra steep hills, would slip excessively
These bikes are listed as very expensive, so I don't expect to see many of them on the road. However, they clearly knew that spinning a reasonably small motor faster and then reducing it down more was an option, and they clearly knew that giving the motor the use of the bikes gears would be a benefit, so...the configuration that is actually being sold to the public is puzzling.
The Euro-spec is 250W using 2.5A (one dealer in France), the Canadian version is 500W / 5A (not that 5A is a huge improvement).
____________________________________________________________________________
Here's the patent pic of the production version. The brushless DC permanent-magnet radial-flux rotor is directly connected to the small drive pulley. The pedal-axle is completely independent of the motor, and the fixed motor-shell and stator are bolted to the bikes frame. The rotor in the motor turns at only 1/4th the RPMs of the wheel...a terrible waste of an opportunity.
The numbers are upside-down, but this is from the orientation of the rider in the seat looking down at the motor. The Poly-V pulley is on the left, chainring not shown.
This configuration is in the patent, I don't know how much of it they can actually own and enforce. The motor has a belted reduction on the left to a jackshaft, and the right side chain presumably uses the bikes gears in a dual parallel right-side drive (like RWPs eCortina). The low-torque primary reduction may have actually worked well with a Poly-V belt (we'll never know), but the version they didn't use has a toothed belt, and the single-stage production version doesn't (whaaaat...huh? thats backwards)
As I see it:
Good:
Motor weight is central
Rear tire is light and no increase of flats or broken spokes, flats remain easy to fix
Gearless motor + belt-drive is very quiet
Battery mass and weight are in perfect location
Bad:
Price is unusually high, especially for low power and no suspension at all
Proprietary parts cannot be upgraded with 3rd party units, or repaired.
(custom Kv motor, ultra high voltage battery, ultra low amperage controller)
lots of custom engineering just to end up with a one-speed motor for a 250W/500W system.
no front disc brake, but does have mounts for aftermarket bolt-on.
Poly-V belt system means no possibility to hot rod for extra steep hills, would slip excessively
