edamame
10 W
Hey y'all,
After reading a bunch here I went and bought a broken Ultra Motor A2B Metro off of Craigslist a few months ago. The previous owner ran over something in the road that got wrapped up in the rear hub and it shorted out a new motor he had only had for a month or so. I watched it sit on Craigslist for a while while I was doing research so after about a month I went up to Austin to check it out. I ended up buying it for $500 which I thought was a good deal for a bike that I wouldn't have to reengineer everything to ride electric. Lucky me, it also had the secondary battery.
I took off the rear wheel and could see where the ground wire had ground out and shorted out against the axle so I pulled the tire and stripped the spokes off to pull the case halves of the motor apart. This is what I saw:
I planned to turn this into a quasi-legal 40mph scooter so I removed the 36v motor controller by taking out the mounting screws and cutting the pins for the three hall senders. I wired the three phase wire pairs to 12 AWG THHN wire with the help of a local motor builder (John at Massengale Armature Works-Thanks!).
Here it is ready to go back together:
I used heat transfer epoxy to glue in a thermocouple to the windings to keep tabs on motor temp:
The 12 AWG wires were as big as I could go:
So I had a friend help me push the aluminum case halves together with a press and I tested it with a Crystalyte 40A Sensorless controller from Ebikes SF. It worked! So I had the wheel rebuilt with the stock parts. I bought an extra stock torque arm since the stock A2B only comes with one which is dumb!
Because I planned on going almost twice as fast as stock I bought new front and rear BB7 brakes with 205mm in front and 185mm in back:
After riding for a couple of weeks at 20S (80-84v) I found the stock mild steel torque arms were as soft as lead:
Here's a stock torque arm on the right with 100 miles on it compared to my laser cut SS version with 600 miles on the
left:
I put 1 torque arm on the outside of each dropout in the stock location and two on the inside on the cluster side (4 total) to replace a 1/4" thick aluminum spacer. Overkill!:
Here's a pic of the early times when I was running the front and rear stock battery in series. You can see my data logger for motor temps on the rear rack:
I bought four HK 10S 5800mah stick pack RC Lipos (20S, 2P) and stuck them in an empty rear battery case:
I charge them only on solar power:
The bike has been pretty much bulletproof. My work is 2.3 miles from home and so on most days I ride 9.2 miles. People try to kill you in San Antonio if you drive too slow so I run about 35-38 mph on the busy stretch which is only 1/2 mile of the 2.3 miles. I like to pass cars! At top end the bike is pretty much tapped out handling wise.(Edit: I fixed the handling by moving the batteries mid-ship.) I have a Fox float RP23 rear shock with 275 pounds of air pressure in it and it is not enough to keep the rear wheel from hitting the bottom of the battery case on big dips so I pick my butt off the saddle when those come along.
The stock batteries did work at 20S/72 volts but after getting the 21Ah of RC Lipos I cannot go back. The BMS on one of the stock batts would cut out if I asked for too much throttle at a time which was annoying. The RC Lipos don't do that but they will stutter if I ask too much of them. As for motor winding temps, the most I have see was 227F a week ago with 100F ambient and I was pushing it as hard as it would go. (Average temps on my way to work and back are about 125-150F.) A guy in an Alfa passed me barely and at the next light I asked him how fast his speedo said I was going--40mph slighly downhill. My cycle analyst is not yet programmed correctly for shunt value so my numbers are off. The bike works though and when the weather cools off I'll fix the little things.
I bought a new seat, the Forte Easy Rider from Performance bike and I like it alot. I enjoy riding to work even in this infernal heat. I'll like it even more when the weather cools back off.
Anybody wanna know any details not mentioned here?
After reading a bunch here I went and bought a broken Ultra Motor A2B Metro off of Craigslist a few months ago. The previous owner ran over something in the road that got wrapped up in the rear hub and it shorted out a new motor he had only had for a month or so. I watched it sit on Craigslist for a while while I was doing research so after about a month I went up to Austin to check it out. I ended up buying it for $500 which I thought was a good deal for a bike that I wouldn't have to reengineer everything to ride electric. Lucky me, it also had the secondary battery.
I took off the rear wheel and could see where the ground wire had ground out and shorted out against the axle so I pulled the tire and stripped the spokes off to pull the case halves of the motor apart. This is what I saw:
I planned to turn this into a quasi-legal 40mph scooter so I removed the 36v motor controller by taking out the mounting screws and cutting the pins for the three hall senders. I wired the three phase wire pairs to 12 AWG THHN wire with the help of a local motor builder (John at Massengale Armature Works-Thanks!).
Here it is ready to go back together:
I used heat transfer epoxy to glue in a thermocouple to the windings to keep tabs on motor temp:
The 12 AWG wires were as big as I could go:
So I had a friend help me push the aluminum case halves together with a press and I tested it with a Crystalyte 40A Sensorless controller from Ebikes SF. It worked! So I had the wheel rebuilt with the stock parts. I bought an extra stock torque arm since the stock A2B only comes with one which is dumb!
Because I planned on going almost twice as fast as stock I bought new front and rear BB7 brakes with 205mm in front and 185mm in back:
After riding for a couple of weeks at 20S (80-84v) I found the stock mild steel torque arms were as soft as lead:
Here's a stock torque arm on the right with 100 miles on it compared to my laser cut SS version with 600 miles on the
left:
I put 1 torque arm on the outside of each dropout in the stock location and two on the inside on the cluster side (4 total) to replace a 1/4" thick aluminum spacer. Overkill!:
Here's a pic of the early times when I was running the front and rear stock battery in series. You can see my data logger for motor temps on the rear rack:
I bought four HK 10S 5800mah stick pack RC Lipos (20S, 2P) and stuck them in an empty rear battery case:
I charge them only on solar power:
The bike has been pretty much bulletproof. My work is 2.3 miles from home and so on most days I ride 9.2 miles. People try to kill you in San Antonio if you drive too slow so I run about 35-38 mph on the busy stretch which is only 1/2 mile of the 2.3 miles. I like to pass cars! At top end the bike is pretty much tapped out handling wise.(Edit: I fixed the handling by moving the batteries mid-ship.) I have a Fox float RP23 rear shock with 275 pounds of air pressure in it and it is not enough to keep the rear wheel from hitting the bottom of the battery case on big dips so I pick my butt off the saddle when those come along.
The stock batteries did work at 20S/72 volts but after getting the 21Ah of RC Lipos I cannot go back. The BMS on one of the stock batts would cut out if I asked for too much throttle at a time which was annoying. The RC Lipos don't do that but they will stutter if I ask too much of them. As for motor winding temps, the most I have see was 227F a week ago with 100F ambient and I was pushing it as hard as it would go. (Average temps on my way to work and back are about 125-150F.) A guy in an Alfa passed me barely and at the next light I asked him how fast his speedo said I was going--40mph slighly downhill. My cycle analyst is not yet programmed correctly for shunt value so my numbers are off. The bike works though and when the weather cools off I'll fix the little things.
I bought a new seat, the Forte Easy Rider from Performance bike and I like it alot. I enjoy riding to work even in this infernal heat. I'll like it even more when the weather cools back off.
Anybody wanna know any details not mentioned here?
