Help! My E-Bike setup is too SLOW!

[sam1am]

Hey guys - hoping you can help me out here. I've got my E-Bike all set up and my max speed is just slower than I feel it should be. Hoping I could provide some detail and maybe you guys could tell me where I've gone wrong.

Bike: This is a front-loader cargo bike with a 26" wheel on the back and a 20" wheel on the front (pictured without the motor).

Motor: The motor is a Crystallite FHT3525 mounted in the front 20" wheel.

Controller: This is a Crystallite 48/72V-50A controller

Battery: 48V/20Ah Lithium Polymer battery

Controller setup:

Current: 50
Voltage: 48
Min-voltage: 43.3 (battery builder recommended 42, so playing it safe)
Wheel size: 20 (I have also tried putting it all the way down to 5)
Mode: Speed (the number 3 flashes on the screen)
Speed: 60 Km/h

My actual max speed is around 12-14mph. I would like to get up to the max US speed of 20mph.

Off the line torque feels good and it gets up to speed reasonably quickly, but just doesn't want to go any faster.

Any ideas? Thanks in advance.

 

[neptronix]

Your motor winding is too slow for that small wheel.
That motor really belonged in your rear 26" wheel and would have probably hit 20mph.

Go play with the ebikes.ca simulator here for a while and you will see what i'm saying: http://www.ebikes.ca/tools/simulator.html

 

[sam1am]

Hmm.. that's what I was afraid of. Crystallite should maybe note sell that motor on a 20" wheel, or at least warn people that it won't be able to reach legal speeds.

So my options are:
1. Re-wind the wheel? Is this possible?
2. Trade or sell/buy a new motor (anyone want a slow winding?)
3. Put the motor on the back wheel. (Is this possible with a front wheel motor or does it need to be a specific different motor?)

 

[sam1am]

Although from what I can tell, I should still be able to hit almost 20mph, or am I reading this right?

 

[neptronix]

Your bike is not anywhere close to being aerodynamic as a full recumbent.
It's less aerodynamic than a mountainbike, for certain.

Select mountainbike as the vehicle and then assume we're talking about a worse case scenario than that.

You're gonna need another motor.

 

[wesnewell]

What you need on that setup is a 72V battery pack. That will get you plenty of torque and speed. Since your controller is rated for a 72V pack, you will just need to set it for 72V. Or you can change the motor. to an H3540, H3548, or similar motor in the 20" wheel. So you can keep the same motor and up the voltage, or change the motor and keep the same battery. Oh, I wouldn't take any more advice from the person that told you to get your current setup.

 

[neptronix]

72v might get him up to 20mph.
Kinda sad speed per volt though.

Then again, that's coming from a guy who has a crazy low turn count motor and sees 40mph on 48v, lol.

 

[amberwolf]

2. Trade or sell/buy a new motor (anyone want a slow winding?)

If you went with the 3548 it would work; I use the HSR3548 in 20" on CrazyBike2's rear wheel, on a 48V pack (14s EIG NMC). The startup / hill torque might'n't be as good (I get that by having a motor in each wheel).


Alternately, a much higher voltage would also work.

 

[dogman dan]

IMO, he does have the right motor, in the right wheel size, for a big ol cargo bike. But 72v would perk it up.

If you do want to buy a new rear motor in 26", I'd advise buying the same type motor. A faster wind in 26" will suck out a lot more of your range on starts and stops with such a heavy bike.

If you buy a new front motor, then a faster wind would be ok, because of the small wheel. You could get a less powerful (9 continent, muxus, golden) but faster 9x7 or 10x6 wind pretty cheap. Look for a screaming deal on some used one, here on ES.

Run 72v, once you can afford the battery investment. If nothing else is possible economically, you could even stack some lead batteries to jack up your voltage to 60v. Or add some 6s RC lipo. Whatever works, to at least give you some speed for shorter rides.

Eventualy, get a 24v 20 ah pack to connect in series with your existing battery.

I'm curious though, what is your speed? 15mph? That is a bit slow even for me. But if you have 18 mph now, that's the best speed for efficiency without being crazy slow anyway.

 

[dogman dan]

I don't see any $100 nine c clones in the for sale, But here's a rear HT crystalyte in 26"

http://endless-sphere.com/forums/viewtopic.php?f=9&t=70938

 

[Drunkskunk]

I'm curious what your unladen wheel speed is. Lift the front wheel at full throttle and check the speed. If it turns out to be about the same, then I would suspect some kind of speed limit. you're hitting the EU legal 25KPH. I would check that first.

Otherwise, you have the aerodynamics of a brick wall on wheels. You need more voltage.

 

[MadRhino]

Hmm.. that's what I was afraid of. Crystallite should maybe note sell that motor on a 20" wheel, or at least warn people that it won't be able to reach legal speeds.

So my options are:
1. Re-wind the wheel? Is this possible?
2. Trade or sell/buy a new motor (anyone want a slow winding?)
3. Put the motor on the back wheel. (Is this possible with a front wheel motor or does it need to be a specific different motor?)

They sell any motor in any size of wheel, and the builder is responsible to reach his target performances.
Many are running this motor 100v hot in a 26" wheel, the rear version of it of course.

You need another motor, rear version, to put on the rear. Yet you could keep it as is and feed it more volts as said previously, to reach your target speed. The 2nd solution seems better, quicker and cheaper to me, since a lightweight motor does cool much better in a smaller wheel.

I would recommend a bigger motor in the 26" rear wheel, especially for a cargo bike. That would make a better build, at extra cost.

 

[John in CR]

Sounds like a speed limit issue. Try the other speed settings as well as trying it with the switch disconnected. If those don't make a difference it could be programmed incorrectly. While you are making a pretty big hole through the wind unless you're going into a headwind, wind resistance isn't the thing holding you back at just 12-14mph. Checking the no-load speed as Drunkskunk suggested will tell you that. Set the speed limit to 100, since maybe that's a % of top speed, not the speed limit.

If it's not the controller, then it could be the throttle itself not providing the correct full throttle voltage.

Talk with the vendor about what rpm or speed you should get on 48V, and the issue you're having. Worst case, if that FHT indicates a slower wind than is in the simulator for the 3525, then increase the voltage. If you don't have much in the way of hills to tackle with a full load in the box, then you have enough motor in the correct size wheel. Increasing the wheel size is never the right answer unless it's for aesthetic reasons or you have pedal strike issues.