Rated Power: 1000W
Max Efficiency: 82%
Voltage: 48V
Gear Type: Planetary Gears
Weight: 9.0kg
Noise: <60dB Speed: <45km/h (16 inch)
From e-ride.ca, the motor is advertised as a 500W motor, so I could be looking at the wrong motor on Samhyun's site, but everything else matches up. E-ride.ca goes on to say that the motor runs at: 5400rpm with a reduction of 15:1 at 17A and 70Nm or torque.
Therefore:
Max Wheel Speed: 5400rpm/15 = 360rpm
For 26"x1.75" Wheel, Circumfrence=2.045m
Speed: 2.045m/rev * 360rev/min *60min/h *1km/1000m = 44km/h (for 26" wheel)
This speed should be achieved at 48V, 17A, 70Nm as per the website.
Now that I have the kit on my bike (26" wheels), I tested the kit with three different voltages and no load:
20V: 20km/h
40V: 40km/h
60V: 60km/h
(very interesting relationship)
Therefore, the Max speed of 45km/h posted on the Samhyun website must be for a motor running with no load and 45V (48V pack). I have been riding the bike for a few weeks now, and the maximum current I have ever seen the motor draw is 17A (full throttle). I haven't ridden the bike with less than 60V, so I can't give test results for 20V and 40V, but under load, I have achieved:
60V: 40km/h (me on bike - 165lb, flat road, no pedaling,17A).
P = 17A*56V = 952W
When I first got the motor, I took it apart to see what a geared hub motor looked like. There are pictures attached below. Inside the motor I found a bunch of aluminum shavings where the bearing was obviously spinning in the housing. I cleaned out the shavings and re-seated the bearing (which definitely isn't press fit), and put it back together. I haven't checked it since, but I'm hoping that I fixed the problem.
The specs on the Samhyun website says that the motor is a 48V motor, but I've been riding the bike for a few weeks now at 60V. After riding at full throttle for a long time, the motor hasn't even been warm, even at 17A continuous! I think that part of the reason is that the wires going to the motor look like they're only 18g, or even smaller, so maybe they're limiting the current, which may not be so bad since they are easier to replace than the windings in the motor. Samhyun must have done this purposely I would guess.
The motor took a little longer to get on the bike that I would have liked because I had to build the wheel, and I had to grind down the axle (scary). Building the wheel was fine, and I used a 1-cross spoke pattern since that's the length the spokes were for. Mounting the wheel to the bike was a different story. The axle didn't fit in the dropouts, so after reading that I shouldn't be installing the hub in a fork with aluminum dropouts, I decided that I better not shave off any of the aluminum, although I did shave off the paint with a knife to gain a couple of mils. The motor axle has two flat sides along most of the shaft, except where the axle sits in the dropouts. The 3/4" of axle on each side of the motor was round, so I had to grind it down to match the rest of the axle, and even a little more. The grinding went surprisingly well, and I actually feel pretty good about how the motor now mounts in the dropouts because it's a tight fit, and because the round sides of the axle are quite a bit thicker than the skinny sides, there is no way that the axle can spin in the dropouts unless the dropouts bend open, but I tightened the bolts enough to keep that from happening (I hope).
5 comments:
Hi Luke,
Great description of work you have done on kit. It inspired me to buy the same kit.
After examening the kit first hand I am not so sure.
Questions:
1) After using your e-bike for 6 months what is your opinion of it and what are your remarks?
2) Did you have any problems with the shaved axel mounting of the moter on front fork ?
3) Any additional help is extremly welcome ?
Hi Luke,
Great description of work you have done on kit. It inspired me to buy the same kit.
After examening the kit first hand I am not so sure.
Questions:
1) After using your e-bike for 6 months what is your opinion of it and what are your remarks?
2) Did you have any problems with the shaved axel mounting of the moter on front fork ?
3) Any additional help is extremly welcome ?
March 30, 2009 10:02 AM
Hey Peca,
I just rode to town today and back (as I do often) to get groceries. There's a very steep up hill on the way home. I always pedal up the entire hill because if I don't I believe that I'd slow right down and most likely stop, but I could be wrong since I haven't actually tried it. With full throttle and pedaling my speed stays above 20km/h on the hill drawing 17A with the voltage usually dropping to around 53V from the normal 60V.
With normal riding (always pedaling) on the flat/slight down hill/ slight uphill the speed stays around 45km/h - sometimes 50, sometimes 40. At 60V this motor will not really go any faster than 50km/h, or pull you up a big hill without pedaling.
I have had no problems with the shaved axle, but please don't come after me if you shave yours and it falls apart or brakes. When I ground mine down with an angle grinder, I was extremely careful to not take any more material off than was completely necessary. I still don't have torque arms on the axle, so I never accelerate too quickly, and just hope that the aluminum doesn't crack. I tightened the nuts on the axle extremely tight so it won't spin and it never has.
For others wanting to purchase this kit, please note that my run time is not extremely long. I use the bike for riding to work (flat 12km), and riding to town and back (huge hill 10km). I always charge after the 10km - 12km as the batteries don't last 24km. The three 20V, 6AH Yardworks Lithium batteries won't go much further than the 12km or 10km, so if your plan is to ride 20km, you won't have enough stored power with this setup - that is if you ride at full throttle, as I do, which keeps the current between 10A and 17A (5A coasting down slight downhills). If you ride slower (30km/h), you should be able to go twice as far because the current draw is around 6A or less. Since I can ride my road bike at 30-35km/h to work, I don't see the point. I got the electric bike so when I don't have much time to get to work, I can still ride.
Additional info:
I'm 6' tall, weigh 170lb. The bike is steel and weighs 50lb with everything (including 3 batteries). A heavier rider/bike would not take you as fast/far or have enough torque to pull you up a steep hill without pedaling.
I like the lightness of the motor and the fact that it freewheels because if the batteries do go dead or something happens to the wiring, the bike isn't that bad to ride.
The motor is geared, so it does make noise, and people do notice that you are riding an electric bike.
I forget if I mentioned that I also had to grind down the bushings between the motor and the fork because they were too wide and I had to bend the fork out too much. Everyone suggested I lathe them down so they were perfectly flat, but I just used a file.
Thanks Luke!
It is very comforting to hear that motor is running and that you sound happy with it. Thanks for taking time to reply.
I was building the bike with help of few friends, and one of them, civil engineer, suggested that either front of rear fork can be spread up even 2" without major problem. The motor that I got looked slightly different than your motor. It had extensions to screw on a freewheel on both sides. E-ride people offered to give me same motor as you got, where somebody had taken of the treads for freewheel, but I figured that it would be better to put 5 speed freewheel (even 7 speed freewheel can be fit with no problem) on motor. So motor was mounted on rear wheel. Not all speeds yet work, but we are working on that. With a little work I am sure that we can arrange the front sprockets to have all speeds working properly.
Thanks for great description of controler. Two of us working on the motor are electrical engineers ( I guess you are too), but we decided to run motor from 40V not 60V but decided that it will be better to arange 4 Yardworks batteries as 40V - 12Ah topology. So far we have only 40V-6Ah (two yardworks batteries). Again, thank you for suggesting the batteries. Your posting was an inspiration. According to yor suggestion we did change the R6 in controler from 15 kOhms to 12kOhms to drop LowVoltageCut-off to around 35.5V to save batteries.
With 40V- 6Ah batteries it seems that with no pedaling it is easy to get more than 12km range with approximately 200 m vertical ascend for person around 180 lib. For peson arond 250 lib, with pedaling we got about 20km and about accoumulated 250m vertical (for 1.0km grade was about 10% and speed about 14km/h). These are initial data. Quite happy with the motor for now.
Thanks,
Peca
Hi
Nice to see your description about the motor. I have worked in Samhyun and infact , I have designed this motor from Scratch.
I am happy to see this.
Murali
http://www.evhub.biz
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