Hi there!
I've been lurking here for a few months as I debated converting an existing bike, I've just recently bought the bits and got it all wired up and working (sort of). I've ran into an irritating issue that seems like it needs some good old forum expertise to try and crack since I've driven myself mad trying to suss it out.
The short version is: I want to run my bike restricted to 15mph but my current configuration is stuck at about 10mph and I've no idea why. Power is no problem, hill climbing performance is fantastic, but the motor simply tops out at around 10mph and won't provide an ounce of assistance above that. I've tried my best to work out where the problem might lie so here's the long version:
I'm using a front hub drive wheel I bought off bankrup bike parts on ebay ( http://www.ebay.co.uk/itm/WHEEL-WITH-ELECTRIC-FRONT-WHEEL-DRIVE-HUB-MOTOR-36V-VOLT-250W-WATT-E-BIKE-ETC-/391454003666?). Admittedly this was a bit of a gamble although I figured a lot of these 36V 250W hub motors are alike and the price was good. It's a hall sensored motor and it's installed in steel forks with a pair of torque arms for maximum robustness.
I bought the controller from Panda ebikes. According to them, the controller is unrestricted and the restriction is provided by a special LED (not LCD) display I ordered alongside. It's the standard '880' style display and the controller label says 'speed set: 1-4.2v' on it so I assume the way this restriction works is the display sends a voltage down one of the signal wires that corresponds to 15mph. Bear this in mind, because one of the first things I tried was removing the display and shorting the controller on directly with the red/blue wires and it's not made any difference to the problem.
I'm using 12S lipo (48v) as power and I've seen the motor consume 1000W under heavy loading so evidently there's no issues with current delivery (I know 1000W will cook the motor in short order, it's much less than than in normal use, just noting the batteries and controller definitely can deliver the power).
At the moment I'm awaiting a PAS so I've got a twist throttle on. This takes us into the whole 'independent throttle' area that's a favourite debating point I've noticed....can we leave that discussion aside for now and focus on getting this bike going properly. I'm not all that enamored with the throttle anyway so it may be coming off.
So, 48v controller on a 36v hub and even with the controller supposedly destricted the power runs out completely at 10mph. Below this there's ferocious torque for acceleration and hillclimbs as long as the speed doesn't reduce to a crawl. I thought maybe I got some motor that's geared entirely for hills and I'm up against the max RPM of the motor, unlikely at 48v though, and I don't think this is the case based on the following:
Today I put the bike in a stand and tried running it with the wheel free. If I give it max throttle from a standstill the wheel accelerates up to 20mph and stays there for a second or two, then it gradually winds down to 12mph and settles there. If I briefly apply the brake the load seems to spur it on and it will again surge and accelerate faster and then slow down again. So I don't think I'm reaching max motor RPM at 12mph, something is limiting how fast the controller wants to spin the motor.
Bit of a long read I know. I've got a decent background knowledge in electronics but this has got me stumped, I just can't figure out where the restriction is coming from. I'll get some photos up tomorrow if it will help, I'd be willing to pick up another controller if that may be the problem.
Thanks.
I've been lurking here for a few months as I debated converting an existing bike, I've just recently bought the bits and got it all wired up and working (sort of). I've ran into an irritating issue that seems like it needs some good old forum expertise to try and crack since I've driven myself mad trying to suss it out.
The short version is: I want to run my bike restricted to 15mph but my current configuration is stuck at about 10mph and I've no idea why. Power is no problem, hill climbing performance is fantastic, but the motor simply tops out at around 10mph and won't provide an ounce of assistance above that. I've tried my best to work out where the problem might lie so here's the long version:
I'm using a front hub drive wheel I bought off bankrup bike parts on ebay ( http://www.ebay.co.uk/itm/WHEEL-WITH-ELECTRIC-FRONT-WHEEL-DRIVE-HUB-MOTOR-36V-VOLT-250W-WATT-E-BIKE-ETC-/391454003666?). Admittedly this was a bit of a gamble although I figured a lot of these 36V 250W hub motors are alike and the price was good. It's a hall sensored motor and it's installed in steel forks with a pair of torque arms for maximum robustness.
I bought the controller from Panda ebikes. According to them, the controller is unrestricted and the restriction is provided by a special LED (not LCD) display I ordered alongside. It's the standard '880' style display and the controller label says 'speed set: 1-4.2v' on it so I assume the way this restriction works is the display sends a voltage down one of the signal wires that corresponds to 15mph. Bear this in mind, because one of the first things I tried was removing the display and shorting the controller on directly with the red/blue wires and it's not made any difference to the problem.
I'm using 12S lipo (48v) as power and I've seen the motor consume 1000W under heavy loading so evidently there's no issues with current delivery (I know 1000W will cook the motor in short order, it's much less than than in normal use, just noting the batteries and controller definitely can deliver the power).
At the moment I'm awaiting a PAS so I've got a twist throttle on. This takes us into the whole 'independent throttle' area that's a favourite debating point I've noticed....can we leave that discussion aside for now and focus on getting this bike going properly. I'm not all that enamored with the throttle anyway so it may be coming off.
So, 48v controller on a 36v hub and even with the controller supposedly destricted the power runs out completely at 10mph. Below this there's ferocious torque for acceleration and hillclimbs as long as the speed doesn't reduce to a crawl. I thought maybe I got some motor that's geared entirely for hills and I'm up against the max RPM of the motor, unlikely at 48v though, and I don't think this is the case based on the following:
Today I put the bike in a stand and tried running it with the wheel free. If I give it max throttle from a standstill the wheel accelerates up to 20mph and stays there for a second or two, then it gradually winds down to 12mph and settles there. If I briefly apply the brake the load seems to spur it on and it will again surge and accelerate faster and then slow down again. So I don't think I'm reaching max motor RPM at 12mph, something is limiting how fast the controller wants to spin the motor.
Bit of a long read I know. I've got a decent background knowledge in electronics but this has got me stumped, I just can't figure out where the restriction is coming from. I'll get some photos up tomorrow if it will help, I'd be willing to pick up another controller if that may be the problem.
Thanks.
