Update:
The Yardworks batteries have lasted just over a year. I do not recommend them for an e-bike. They now die really quickly (seem to use around 2Ah), and can't handle the 17A current they used to without the BMS system shutting off the battery.
I read something recently about Lithium batteries with a battery meter that the BMS system needs to be re-calibrated by running the batteries almost dry at a low current draw (I forget how dry exactly). This apparently re-calibrates the BMS so it doesn't shut off the batteries too soon. I haven't tried this because I have pretty much given up on the batteries...
Sunday, August 1, 2010
Tuesday, September 30, 2008
First Post
I'm writing this blog to publish information about my electric bike hub motor, controller, and batteries. In the future I hope to add more information about how well my electric bike components work, and continue to work as they become old and worn. In the end I hope to help others learn as much about electric bikes as I have, and I'd like to help them make a decision about whether the kit I got would be right for them!
My Kit
I bought my electric bike kit from Steve at www.e-ride.ca. Somehow www.e-ride.ca is linked to www.greenwit.com, and it seems to be that Steve imports the bikes and kits through his company Greenwit, and has a few retail outlets, one of which is e-ride where he sells the imported goods.
I spent a lot of time looking at the kits sold online, there are a ton of online sites, especially in British Columbia which sell tons of different kits. I almost bought a kit from www.ebikes.ca, and it was hard not to buy one from them because I had spent a summer working in the Engineering Power Lab at UBC with Justin (the guy who started ebikes.ca). In the lab Justin was researching different brushless drive algorithms and PWM schemes to optimize the efficiency of the motor. After seeing how much Justin knew about electric bikes, and how thourghly he tested all the components and kits before choosing which kits to sell, it was hard not to buy a kit recommended by him and sold at ebikes.ca. Take a look at the simulator on their site to get a feel for the talent and knowledge behind their kits.
The kit I ended up purchasing from e-ride.ca is the Motorino-500 which consists of a 500W geared hub motor, a 48V 17A controller, a hall-effect based thumb throttle, two brake leavers, nice thick spokes (possibly DT?) for a 26" wheel, and a carry case.
I ended up buying the kit from e-ride because of the weight of the geared hub motor, and because of the price ($500CAD). As a bonus, once the kit arrived, not only was the hub motor light weight (around 10lb - I should have weighted it before I built the wheel), but the controller was very small too!
Before I bought the kit, I tried to get as much information about the kit from Steve as I could, but he wasn't able to tell me much of anything. However, after receiving the kit, both the motor and controller have Samhyun and Hirun stamped on them.
It seems that Samhyun (www.samhyun.co.kr) is the manufacturer of the hub motors and controllers in Korea, and they make lots of different motors and controllers.
Hirun (www.hirun.co.kr) is also in Korea, and they seem to sell pre-built electric bikes. I was able to get more information about my hub motor and controller from those sites, but I will post it later.
I spent a lot of time looking at the kits sold online, there are a ton of online sites, especially in British Columbia which sell tons of different kits. I almost bought a kit from www.ebikes.ca, and it was hard not to buy one from them because I had spent a summer working in the Engineering Power Lab at UBC with Justin (the guy who started ebikes.ca). In the lab Justin was researching different brushless drive algorithms and PWM schemes to optimize the efficiency of the motor. After seeing how much Justin knew about electric bikes, and how thourghly he tested all the components and kits before choosing which kits to sell, it was hard not to buy a kit recommended by him and sold at ebikes.ca. Take a look at the simulator on their site to get a feel for the talent and knowledge behind their kits.
The kit I ended up purchasing from e-ride.ca is the Motorino-500 which consists of a 500W geared hub motor, a 48V 17A controller, a hall-effect based thumb throttle, two brake leavers, nice thick spokes (possibly DT?) for a 26" wheel, and a carry case.
I ended up buying the kit from e-ride because of the weight of the geared hub motor, and because of the price ($500CAD). As a bonus, once the kit arrived, not only was the hub motor light weight (around 10lb - I should have weighted it before I built the wheel), but the controller was very small too!
Before I bought the kit, I tried to get as much information about the kit from Steve as I could, but he wasn't able to tell me much of anything. However, after receiving the kit, both the motor and controller have Samhyun and Hirun stamped on them.
It seems that Samhyun (www.samhyun.co.kr) is the manufacturer of the hub motors and controllers in Korea, and they make lots of different motors and controllers.
Hirun (www.hirun.co.kr) is also in Korea, and they seem to sell pre-built electric bikes. I was able to get more information about my hub motor and controller from those sites, but I will post it later.
My Bike
My bike is an old Rocky Mountain Hammer Race with a Marzocchi Bomber Z3 front fork. I had read people cautioning not to use a front hub motor with a fork with aluminum dropouts. The Z3 fork has aluminum dropouts, so I contacted Marzocchi to try to get some information about the fork strength because I planned to mount my hub motor on the front. I never did get any information from them, but I decided in the end that the dropouts looked thick enough, and because the fork had stood up to years of mountain biking and going off of big jumps and drops, I felt it would hold up to the extra weight and torque.
My Motor
My motor is made by Samhyun (www.samhyun.co.kr) in Korea. I was able to get the specs from their website:
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).
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).
My Controller
The controller that came with the kit is awesome! It's specs are available from Samhyun (www.samhyun.co.kr):
Voltage: 48V
Control Type: PWM (Current control)
Current Limit: 40A
Low Voltage Protection: 42V
Throttle Voltage: 1V~5V
Operating Temperature: -30 ~85 deg.C
Cruise Mode: Manual/Automatic
Speed Mode Control:Low/High
When I got the kit, I didn't have my bike setup for the motor yet, so I played with it on my desk. I initially tried running the motor at 20V since I only had one battery pack at the time, but when I pressed the throttle the motor spun for a half second and then stopped. I figured that since the motor initially started spinning, the low battery protection turned it off, so what was the first thing I did after receiving the kit and trying it out? I opened up the controller! It's actually built really well (I think), even though I've blown two of the Mosfets (my fault).
Specs of controller internals (by inspection):
MCU: PIC16F73 Microcontroller (Haven't read out PIC program yet)
Mosfets: 6x STP75NF75 (75V, 80A, <0.011ohm Rdson) TO-220 Package
Mosfet Driver: 3x IR2108
15V Regulator: LM2575HV
Parts Hidden by regulator board (unimportant but not visible unless you take the board off):
LM2903: Dual Differential Comparator (for high side mosfet driver signals)
SN74HC00: Quadruple 2-Input Positive NAND Gate (for high side mosfet driver signals).
To change the low voltage cutoff, you have to change resistor R6, connected to input AN2 on the PIC. The initial value is a 15k ohm resistor which sets the voltage cutoff to 42V. I put on a 5k ohm resistor which makes the voltage cutoff around 14V (perfect since I was using a 15V power supply for some testing).
The controller has lots of wires coming out of it, and a few vias inside it which are obviously made for wires, but aren't used. I have decoded the wires to be:
PAS: Pedal Assist System (not sure how this is used, but there are three wires coming out of controller)
Throt: Throttle
SPD_LMT: Speed Limit
CRUZ: Cruise Control (Vias only)
Brake: Brake Cutoff (I connected this to the red button on the throttle)
Single wire from Voltage Regulator: Voltage Display on throttle (uses the ground wire from the throttle connector)
Voltage: 48V
Control Type: PWM (Current control)
Current Limit: 40A
Low Voltage Protection: 42V
Throttle Voltage: 1V~5V
Operating Temperature: -30 ~85 deg.C
Cruise Mode: Manual/Automatic
Speed Mode Control:Low/High
When I got the kit, I didn't have my bike setup for the motor yet, so I played with it on my desk. I initially tried running the motor at 20V since I only had one battery pack at the time, but when I pressed the throttle the motor spun for a half second and then stopped. I figured that since the motor initially started spinning, the low battery protection turned it off, so what was the first thing I did after receiving the kit and trying it out? I opened up the controller! It's actually built really well (I think), even though I've blown two of the Mosfets (my fault).
Specs of controller internals (by inspection):
MCU: PIC16F73 Microcontroller (Haven't read out PIC program yet)
Mosfets: 6x STP75NF75 (75V, 80A, <0.011ohm Rdson) TO-220 Package
Mosfet Driver: 3x IR2108
15V Regulator: LM2575HV
Parts Hidden by regulator board (unimportant but not visible unless you take the board off):
LM2903: Dual Differential Comparator (for high side mosfet driver signals)
SN74HC00: Quadruple 2-Input Positive NAND Gate (for high side mosfet driver signals).
To change the low voltage cutoff, you have to change resistor R6, connected to input AN2 on the PIC. The initial value is a 15k ohm resistor which sets the voltage cutoff to 42V. I put on a 5k ohm resistor which makes the voltage cutoff around 14V (perfect since I was using a 15V power supply for some testing).
The controller has lots of wires coming out of it, and a few vias inside it which are obviously made for wires, but aren't used. I have decoded the wires to be:
PAS: Pedal Assist System (not sure how this is used, but there are three wires coming out of controller)
Throt: Throttle
SPD_LMT: Speed Limit
CRUZ: Cruise Control (Vias only)
Brake: Brake Cutoff (I connected this to the red button on the throttle)
Single wire from Voltage Regulator: Voltage Display on throttle (uses the ground wire from the throttle connector)
Yardworks 20V 6AH Lithium Ion Batteries
I'm using three Yardworks 20V 6AH lithium Ion batteries in series to power my bike. I have them directly connected to each other, and I haven't had any problems. I take them off the bike to charge them. The batteries were purchased at Canadian Tire, and can either be purchased individually, or with a grass trimmer.
When I first looked at getting Lithium batteries, the only ones I could find that seemed reasonably priced were on eBay. The batteries were made and packaged in China and were wrapped in Duct Tape! These Yardworks batteries are still made in China (I assume), but they are encased in a plastic shell, have a dedicated unintelligent (or so it seems) charger, a warranty, and are available from Sea to Sea (to Sea?) across upper North America!
The Yardworks batteries are amazing! There is lots of detailed information about the batteries from other eBike riders here: Yardworks Battery Info so I won't say anymore about them.
When I first looked at getting Lithium batteries, the only ones I could find that seemed reasonably priced were on eBay. The batteries were made and packaged in China and were wrapped in Duct Tape! These Yardworks batteries are still made in China (I assume), but they are encased in a plastic shell, have a dedicated unintelligent (or so it seems) charger, a warranty, and are available from Sea to Sea (to Sea?) across upper North America!
The Yardworks batteries are amazing! There is lots of detailed information about the batteries from other eBike riders here: Yardworks Battery Info so I won't say anymore about them.
Riding info
Here's some info I posted as a comment and I'd thought I'd add as an entry:
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.
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.
More controller info
Here are a few more pictures of the controller board. The small board with the voltage regulator on it was taken off the main board so I could diagnose a problem with the controller. One of the position sensor wires from the motor became de-soldered where I spliced the wire, and in diagnosing the problem and giving the single winding full power (since the controller assumed the motor was at a single position, so it never changed windings - a flaw in the design I think), I blew up a mosfet. At first I thought that just one mosfet was blown (it had a chunk missing from it), but in the end, both mosfets controlling the + and - ends of the winding had blown. I only realized this after the mosfet I replaced immediately blew again, so that's when I took the voltage regulator board off the main board to look at what every chip on the board was doing...
The other small board is from the thumb throttle. Somehow in fixing the position sensor wire I also blew up the hall effect sensor. Luckily IC's are cheap!
Showing components under voltage regulator:
15V regulator
Throttle board
The other small board is from the thumb throttle. Somehow in fixing the position sensor wire I also blew up the hall effect sensor. Luckily IC's are cheap!
Showing components under voltage regulator:
15V regulator
Throttle board
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