Whoa, hey! Haven’t done one of these in a while, though I’ve definitely taken apart a host of things recently that should be written up. I’m doing this now because, as usual, I hope I’ve come upon a useful source of parts for both my own projects and those of anyone else who considers themselves connoisseurs of fine sketchy electric rideable implements. This time interval’s report brought to you in part by Jamison, who I’m glad to announce has joined the ranks of us MIT hoodrats and has been pulled out of the south to become a dirty Yankee. Though, given that he is from Florida, was probably always one to begin with.
The foundations of this chapter of Beyond Unboxing began several weeks ago as Jamison was completing his melonscooter-equivalent, Guavascooter. For the record, the Collegiate Silly Vehicle League nomenclature for the SK3 59 series of motors is guava, following in the 80mm C-series (e.g. the C80/100 and C80/85) being the melon and short melon. Always on the hunt for new shady Chinese vehicle products, Jamison informed me of the existence of what is basically the most shady Chinese parts supplier website I’ve ever seen: eLifeBike.
I think the engrish on the shopping cart software alone is the source of 20 new inside jokes in our crew up here.
What struck awe into me is the sheer absurdity of the prices. How the hell are they so low? What is this stuff actually made of – recycled human hair and potato starch like everything else from China?! We were interested particularly in their line of 6-FET controllers, which seemed to be in the same bloodline as the revered (…) Jasontroller. According to Jamison’s report, it seemed to behave basically like the Jasontroller, but was about 60% of the volume. Seeing such other joys as $66 hub motors and $28 battery chargers, I decided to front some money to offer, once again, to the Gods of Silly Rideable Things. I went ahead and bought said $66 hub motor, a “250W” model; two of the 24V 250W controllers (basically equivalent of the Jasontroller model I buy the most, which can actually run up to 40v reliably), and a 10A 36v battery charger. If any of this stuff so much blinks when I turn it on, I’ll be happy.
As usual, with these exclusively Chinese vendors, the base price is deceptive. Shipping on items can often reach $30-50, if not more! After a week (Fedex International Priority was somehow the cheapest shipping option), I found out why the prices were so low:
Paddy Fields Street? Damn, is this just some guy working out of his straw shack in the middle of a field of rice? Turns out if you Google Maps the postal code 518108, it’s a small industrial neighborhood in northwestern Shenzhen (are there any other kinds?). Given the name, it probably used to be paddy fields.
Here’s all the goods! I can confirm that, at least superficially, they are made of metal and have wires sticking out of them. So I’ve at least gotten these items discerned into one of two categories: small bombs, or electric vehicle products. As far as the NSA is concerned, it’s all the same anyhoo. Hello NSA!
I ordered a 36v 10A charger because most of my daily commuter tools run 36v (or 38.4v) electrical systems, so at least one of ’em ought to benefit from this quicker charger. My currently fastest charger is 5 amps.
Let’s start with this hub motor. As everyone probably knows, I am a purveyor of fine hub motors. This style of hub motor is generally known as the “8FUN” or “Bafun” or “Bafang” motor. In the 250/350W size, they’re around 6″ diameter and are designed for bicycle front wheels, to offer pedal assist and not explicit propulsion power. I’ve been eyeing them for a while, since they are readily available on the Internet of Things, but never sprung for one until now. Since I’m not a big bicycle person, I’m of course interested in how to adapt them to drive smaller wheels such as scooter wheels, or some kind of robot appendage. Or vans.
Six Phillips-head case screws layer, the 8-FUN motor is cracked open. This was suprisingly pleasant and easy.
The observant might note that, in a divergence from my hub motor designs or those of full-size e-bike motors, it’s a geared motor! That’s right – the outrunner style motor on the left actually spins on the stationary center steel shaft, and it has a steel pinion which engages with…
…gears in the planetary gear set.
Alright, hold on a second here. Somehow, the Chinese are able to turn a few lumps of dirt, a rock, and maybe a cup or two of oil into a beautifully machined cast aluminum case, ball bearings, laminated steel stator, neodymium magnets, copper wire, internal and external gear teeth, and laminated lacquer-coated iron stamped shapes, then sell it to me for all of $66 (which is not that much these days, considering the steadily rising Chinese RMB exchange rate)…
…but use PLASTIC gears to complete the great circle of e-Bike life?
I would have gladly paid 10 cents more for some sintered steel, guys.
All over the Internet, the weak link in these motors and the source of much frustration are those little blue (or off-white, or black) nylon gears. The design itself is quite robust, from my appraisal, besides those damned gears. The gears ride on common 608 skate bearings and are retained solidly to the carrier by snap rings, so they never rub on the motor. Typically, small planetary gearboxes just throw you a big wear washer for the gears to mash against and be done with it.
A little more table-bumping and the other endcap pops off, exposing the backside of the motor. The construction of this motor is pretty solid. A full circle of magnets, tight airgap, and an actual PCB that holds the Hall sensors. By itself, this motor is worth the price if I had a specific application for it. It’s extremely utilitarian – for the same price, you’d get a much smaller but much shinier R/C aircraft motor. One of the product lines I’ve wanted to a start is a line of extremely plain, Brutalist styled motors which aren’t all chromed out and sticker-plastered, but, like, actually do work.
In this motor, the stator is rigidly fixed to the shaft, and the can has a short bearing section in it which rides single-supported on the shaft. Not unlike a huge version of Pop Quiz’s weapon motor.
Closeup of the gearset. The motor pinion and outer ring are all metal, but the planetary gears are PLASTIC. Count on the Chinese to cut the 1 corner that would make the product actually worthwhile! The gears seem to be metric module 1, a common size, so perhaps similarly sized metal gears already exist for it – I haven’t done extensive research into this facet of Chinese e-bike parts, since I’m not heavily involved in the crazy e-bike hacker community.
It’s interesting to note that the carrier has an integrated freewheel. That way, you can pedal-power override the motor’s propulsion force. I, for one, actually hate freewheels and like my motor inertia to be a continuous function.
Closeup of the motor, showing the workmanship and method of stator attachment to the hub. The winding-bindings are a nice touch.
fuck plastic gears I think this is a pretty solid product if you run it within its ratings – basically 350W limited power systems for pedal assisting. And in this application, I’m sure it rocks hard or the design wouldn’t be commonplace, but fuck plastic gears I definitely don’t see much overpowering potential in it due to the fuck plastic gears.
I don’t have an application lined up for this little thing, so I put it back together and just ran it on a table for kicks. It’s very quiet – surely the plastic
gears gear-like substance helps with noise absorption. However, one thing Jamison and I talked about, but I have yet to investigate, is whether or not this motor is small enough in diameter to jam into other cored-out wheels. Instant DIY small hub motor!
One of the things that caught my eye when Jamison popped the top on Guavascooter was how small the controller was. It was advertized, yes, as miniature, and I should have look at the size specifications. But the real kicker was when I pulled out a spare Jasontroller:
The QQ 6-fet series is basically a hair more than 2/3 he volume, with the best decrease being on width. The standard 6-FET Jasontroller is 105mm long, 35mm tall, and 66mm deep, compared to 100mm x 30mm x 52mm.
Here’s my Sciencing Rig all set up with a SK3 motor (feat. Sensor Boards). I neglected to take a close-up of the board inside, but the construction is of much higher quality than the corresponding full size Jasontroller. More smaller SMT components are used, resulting in a tighter board, and – my favorite part – the FETs are mounted to the heat sink bar much closer together and at the very base of their leads. There’s no gap between the FET body and the board, so the whole assembly is not wobbly. But it also means I couldn’t just fold back the FET rail to read the part number.
After some very careful light and mirror tricks, I, in my classic habit, found the FET part number: the RU7088R. A bit better than the usual offerings!
As far as I could tell from inspection, the circuitry is exactly the same as the full size Jasontroller, and the chipset is also the same (X8M06-C with a comparator frontend for sensorless operation).
This controller has no “auto-train” wire. Instead, like the full size Jasontroller, any existing motor Hall sensor mapping is erased if you run sensorless. Then you plug in the (hopefully well-placed) Hall sensor rig and run the motor again to full speed, back to zero speed, and cycle power. These things are smarter than I am.
And like the full size, it also has a roughly 550Hz commutation frequency limit. The shown waveform is 15.625kHz PWM frequency on top of the commutation frequency. If the motor wanders above this speed, unlike the full size Jasontroller it doesn’t keep beasting current into it, but rather it shuts down. Upon return of the throttle to zero, it can start up again. So, it seems to be an improvement – instead of grenading itself and your motor, it soft-kills.
550Hz-electrical translates for most 7-pole-pair outrunners to 4714 RPM maximum (550 times a second / 7 electrical rotations per mechanical rotation, then * 60 seconds per minute). Hitting the “3 speed selector switch” into high speed made no difference – again, it’s a processor limit. Sadly, these processors seem to be using their internal oscilltors, so it’s nontrivial to overclock. If the oscillator were external, you could potentially just make it faster.
In summary, for most purposes, the mini-Jasontroller is exactly the full size, but just cuter. The smaller package means you can shove it into many smaller vehicles (specifically scooter frames) where it would otherwise be unwieldy. I’m an immense fan of these things already, but need to get in some more hardcore testing and detonate a few before making a decision on recommending them. But if you’re interested, you can get one from eLifeBike for about $38 minimum (66% of that price is shipping alone). As the purchase quantity approaches infinity, the price appears to settle close to $14-15 a unit. Yes, I tested this on their Engrish-laden cart software.
These two controllers I bought might end up on Chibikart2 for robustness testing.
This concludes another chapter of Beyond Unboxing! If you end up using any of these generic Chinese EV products in anything, feel free to drop a comment. The reason I love to mess around with these parts so much is how care-free they are. There’s no proprietary system or brand or manufacturer’s artificial limits to deal with, the price is right, and they work. One of my beliefs is that the next big EV revolution is quietly taking place in China: the millions of these nameless e-bikes carrying people and goods every day publicity-free, while we scurry around with shiny, low volume, tax-break subsidized people-bubbles built around big money personalities.
(There go my chances of working at Tesla or any other electric car company, ever.)