Crystalyte Motor FAQ
Paul_G
Crystalyte Motor FAQ
What is the difference between all the 400 and 5300 series motors, like 405 verses 408 etc.?
The last digit on a Crystalyte model number indicates the so-called "winding count." The 404 motor has 4 turns of copper around each stator pole, while the 406 motor has 6 turns, the 4011 has 11 turns and so forth. A higher number of turns means that the motor requires a higher voltage to reach the same RPM. The different winding choices provide a great deal of flexibility when choosing a motor option for a certain target speed, since you can independently play around with the battery voltage, the winding count, and the controller current limit to achieve a specific performance. On the other hand, it can also lead to a lot of unnecessary confusion.
In general, if you halve the winding count, you will double the speed of the motor. So a 406 motor is then 33% faster than a 408 motor (8/6 = 1.33) when run at the same voltage. If you run the motors at different voltages that scale with the winding count, then the performance ends up being pretty much identical. A 404 motor at 24V, a 406 motor at 36V, and a 408 motor at 48V will all behave the same. The only difference is that the 404 motor, running at just half the voltage as the 408, would need twice the current in order to achieve the same power output.
Smaller wheels need to spin at a faster RPM in order to reach the same road speed, so for that reason we have generally specified winding counts that decrease in proportion to the diameter. The following combinations at 36 volts will easily be able to maintain the road legal limit of 32kph on the hills and will reach speeds on the flats of about 40 kph:
- 16" wheel - 404
- 20" wheel - 405 or 5303, or 2805
- 26" or 700c - 406, 407, 2806 or 5304
If you want the speed on the flats to be equal to the road legal limit, then for 36V operation we would usually recommend:
- 20" wheel - 406 or 2806
- 26" or 700c - 408, 5305, or 2807
To see the actual output performance for a given battery and motor arrangement, please see our motor simulator page.
Is there a tradeoff between speed and torque?
No, there is a frequent misconception that the hub motor windings are similar to gears in a conventional drive chain, and that as you go to a lower speed you get more torque or visa versa. This is generally untrue. If you were to increase the speed of your motor by increasing the battery voltage, then both the speed and the torque of the motor go up. If you increase the speed instead by leaving the voltage the same and going to a lower winding count motor, then you do get more torque at higher speeds, but ever so slightly less torque off the line because of secondary losses in the wiring and controller.
If high torque is required, it is almost always more efficient to achieve this with a larger, more powerful motor like the 5300 series, as opposed to dumping more and more energy into a smaller motor.
What are the exact specifications (watts, volts, max torque etc.) for motor XX?
This is an annoying question that we get asked a lot, and the answer is that there is no such thing as a "power rating" or "voltage rating" for a motor, that is why we don't provide one. The power that you can get out of a particular hub motor depends on the RPM with which you are driving it at as well as the amount of heat generation that you consider acceptable. Rather than provide a few arbitrary numbers, we have instead written a motor simulator program that tells you exactly how much power a given hub motor will produce over the entire load range for any particular controller and battery combination: Link to Motor Simulator
My motor has a wobble when it spins, is this normal?
Yes, the manufacturing tolerances of the Crystalyte are such that the hub rarely spins perfectly true. It is none the less possible to lace the rim to spin true and centred even if the hub has some wobble.
I just got my motor but can barely turn the axle there is so much resistance, is this a defective unit?
No, with any direct-drive motor there is significant drag force required to turn the hub due to the strong interaction between the magnets and the stator. With the Crystalyte 400 series motors, this is about 0.4 N-m, while the torque to turn the axle of the 500 series is closer to 0.7 N-m. That is more torque than most people are able to apply just with their fingers turning the axle. However, if you mount the wheel on the bike and spin it, you will see that the wheel can still turn more or less freely. If you give it a whirl it should turn 3 or 4 revolutions before coming to a stop. The drag force caused by these hubs is comparable in magnitude to the rolling resistance of the tires on a regular mountain bike.
I plan to ride in the rain and wet weather, how do I waterproof the hub motor?
There are many suggestions on the web that you should thoroughly seal where the wire enters the axle slot using silicone or something similar in an attempt to keep water out of the Crystalyte wheels. But after having serviced several water-damaged hub motors that had been supposedly 'waterproofed', there is no evidence that this helps at all, and it may even make matters worse by keeping water trapped inside the hub. Water can enter the hub not just from the outside of the cable through the axle slot, but also by flowing inside the motor cable sheathing, entering at either the Anderson or hall connectors.
If you do require a waterproof motor, then we recommend with the Nine Continent or eZee system. In their disk motors released in 2009, Crystalyte has added both a rubber sealing ring around the axle as well as sealant to the wire entry point, so it could be that these steps will reduce the likelihood of water entry into the hub. But we would still recommend that you also always store your Crystalyte motor indoors if you are in a wet climate. Crystalyte motors that are stored outdoors over a winter here have often gotten so rusted that they were completely seized with corrosion.
http://www.ebikes.ca/store/store_motors.php
Paul G