Which DD hub motor do I have

[rote]

hey guys,
I've learned a lot here from you guys over the past few months. One thing I can't figure out is what type, brand, windings, magnets, kv, etc. DD hub motor I have. Pic attached and part of the 'Allinone' ebay description is: * Built to the highest international standards, CE * 48V 1000W and 750W super power brushless gearless hub motor * Restricted to 750W and 32km/h by default as a road-legal kit * Nylon tire& alloy rim& stainless steel spoke * Rare-earth metal magnates are used in the motor to efficiently produce large power * Aluminum alloy powerful controller guarantee big current supply. And here's the link: http://www.ebay.com/itm/48V-1000W-Rear-Wheel-Electric-Bicycle-Motor-Kit-eBike-Hub-Conversion-LCD-Meter-/222117405994?hash=item33b73aa52a

I got all the other stuff down. Just would like to know the specs of the hub. If anyone knows just by looking at it, much appreciated. Thanks.

 

[dogman dan]

Brand we cannot tell. but you have a typical direct drive brushless hub motor with magnets 28 mm wide, or close to that. More or less identical to muxus, 9 continent, and golden motors of similar magnet width.

The winding will be either 6 turns or 7. with 6t, you should see 25 mph on 36v. But the controller may actually limit it to 20 mph. More likely, it's just a 7t no real controller limits, and the thing will briefly hit 23 mph, then settle in to 20 mph or less for 90% of your ride.

It's a 500w rated motor, which can easily stand up to 2000w, and some run 3000w as long as the rides at 3000w are of short duration. 72v 40 amps is what most who run 3000w have, and it will briefly hit 40 mph with that. But a long enough run full throttle with 3000w will melt er down. 72v 10 ah battery will generally run out before melt down.

but under 2000w, you have a decent motor that will take quite a beating, as long as the loads are reasonable. By load I mean weight x grade of hill x length of hill. Under 300 pounds, it will climb a 10% grade hill that is miles long.

 

[spinningmagnets]

If you fry a Hall sensor, there is nothing wrong with using a sensorless controller. The only problem is when you are at a complete stop on an uphill...the motor will occasionally "judder" back and forth until you get it rolling a few inches, then the power will kick in.

You should own a sensorless controller as a back-up, and also as a diagnostic tool (down the road). Plus a digital multi-meter (DMM)...eventually.

 

[rote]

dogman, spinningmagnets: thank you both. You are some of the guys I've silently learned from. Interesting that you think it's a 500w motor (although I've learned, as you said, the motors can withstand quite a bit more). I'm in California so don't have a need for the Euro speed restrictions. I have a 48v lithium battery, 22amp controller, so can fairly easily achieve 30mph. At this speed, the watts show about 850-900 on my display. I'm really enjoying my ebike and new e-tinkering hobby.

 

[Alan B]

You can try some of these motors in the Ebikes.ca simulator and find something that matches your results, that'll tell you more about the turn count and capabilities of your motor.

 

[rote]

That ebikes.ca tool was one of the reasons why I wanted more info on my motor. Essentially I would just randomly pick one of the listed motors. :\

 

[wesnewell]

Since it comes from a US vendor, you can be pretty sure it's really a 1000W rated motor and not a 500W rated one. If you look for any numbers on the hub, that nay confirm it. Probably the same as the 48V 1000W yescom kit. A 9.75Kv motor rated for 470rpm at 48V. Their link.
http://www.yescomusa.com/collections/sports-rec/products/26in-rear-electric-bicycle-motor-conversion-kit-48v-1000w

 

[Alan B]

Since you have numbers like speed and power you can try different motors in the sim and match them up. Top speed should sort out the winding, which motor in the sim matches it. Choose motors the same stator width and diameter. The stator width and diameter you can measure, or estimate from the outside. From the voltage and unloaded speed you can calculate Kv.

500W vs 1000W is mostly how the motor is operated rather than a change in the motor itself, eg the voltage and current limits of the controller.

 

[wesnewell]

The people you buy from may screw you by selling you a 500W motor as a 1000W motor, but I can assure you it's not a common practice in the US from legit vendors. It's called fraud, and can land someone in prison. I disproved this BS years ago about the motors being the same. If you buy a 1000W motor in the US, and they send you a 500W motor and refuse to correct it, call the AG. Yes. I know there are dealers that try and trick people with things like peak wattage, etc., but they're either real stupid or just crooks. I'm not going to name names, but I know a few that resort to all kinds of tactics to get around the true specs.

 

[Alan B]

There are a number of defining characteristics of a motor such as Kv, no load current, motor resistance, thermal resistance for heat dissipation, winding turns, copper fill, and magnetic saturation current.

None of these readily measurable terms is a power rating. The power rating is derived from motor characteristics and operating conditions.

Power is a fuzzy characteristic for motors, and not very useful as a comparison value (without a precise and consistent definition of the conditions and measurement technique). As I mentioned before, operating conditions such as available voltage, current and ambient temperature change the RPM, torque and power that the motor can produce, and there are many differing circumstances under which to measure motor power, so a vendor can choose a different technique and arrive at a different value for the same motor. It is common for the same motor to be sold at different voltage levels with different speed and power ratings, for example.

Conducting measurements and comparing to simulator data should work fairly well. Things like no load speed and current, max speed and power on a steep (measured) gradient, etc should allow you to sort through the motors in the simulator that have the same physical dimensions and determine a representative motor that you can use for comparisons in the future.

 

[rote]

Thanks guys. Didn't think my generic request would receive much feedback.

wesnewell - As mentioned, no markings on my hub other than a lightly engraved alpha-numeric which I suppose is a serial number. I hope it is a 1000w hub as advertised but in any case runs fine for my purposes. Fwiw, I think it is a Chinese vendor that just has a small office or distribution center in Calif - so may not necessarily be a U.S. company.

Alan B - thanks for your further insight. With the information you guys have provided along with the ebikes.ca simulator, I hope to correctly deduce the specs. As you mention, I think numerous things come into play. I have what I think is a decent display in a KT-LCD3. I also have one of those generic 130A watt meters that I wasn't able to use until yesterday because the display flickered and was unreadable at my battery voltage. Randomly tore off a resistor on the LCD board and disconnected the led and now can see faint digits. After a ride yesterday, the watt meter indicated a peak watt of 1183 (as mentioned, my display shows 850-900). Fwiw, I haven't done it in a while but I recall near 40mph unloaded when I just lift up the back end.