Any way to slow my scooter way-the-heck down?

[woofnbike]

i replaced the motor on my ebike -- it had bad halls -- with an identical motor, along w/ a new controller. has the same battery. but now the thing goes like a bat out of hell, no matter i choose slow mode or fast. the moment i give the throttle a nudge, the motor jerks a few times then smooths out as a higher speed is reached. i just want it to amble along like it used to do but that's impossible now. and i have no idea what i did to make it act like this. thoughts, anyone?

 

[Theodore Voltaire]

Most controllers allow you to set the max power output. What kind of controller, display, and motor do you have?

 

[fechter]

If the throttle has a large “dead band” before the motor starts moving it will make things hard to control. This can be fixed by placing a resistor in series with the throttle ground line.
There may be ways to tame it down in the software but you’d need the programming setup.

 

[Chalo]

Lower voltage battery would slow the top speed in proportion to voltage, if your controller will tolerate lower voltage. Also it would ease the onset of power/torque somewhat.

Sounds like your new motor isn't identical, but has higher RPM per volt (lower turn count) than the old one.

 

[woofnbike]

it's a bafang motor, one of the so-called jump ones, connected to this: 24V/36V 350W 6MOSFET ebike Electric Bicycle Brushless Motor Controller with LED.

seems to me the resistor idea is the cheapest and easiest solution. what resistor should i look for, if indeed that's the way i should go?

 

[fechter]

The resistor mod really only helps if your throttle has a large dead band at the beginning. You can test this by lifting the wheel and see how far you need to move the throttle before the motor starts. By very slowly advancing the throttle, you should be able to make the motor spin slowly and gradually pick up speed. If you have some kind of sudden jerk when it starts up, you may have a different problem. Since your new motor is the same as the old one, I would have to assume the issue is with the controller.

To try the resistor thing, I would get a 200 ohm, 10-turn pot and insert it in line with the throttle ground wire. Once installed, you adjust the pot until the motor just starts moving, then back off a little.



I've had to do this on a couple of my scooters in the past and it made a big improvement.

The link for your controller needed permission to view. Many of the new ones have some kind of programmability.

One my standup scooter, the throttle was integrated into the display and installing a resistor was not practical. On that one I took a very small chunk of magnet and glued it near the throttle hall sensor to get the same effect. It took some messing around to find the right magnet position, but once installed, it worked very well. The idea is to flatten the throttle curve near the beginning so it is more gradual in the low end. Most hall throttles are very non-linear and start out gradual, then get really steep in the middle. If you have a large dead band at the bottom, the gradual part is bypassed and the motor starts in the steep part.

 

[woofnbike]

here's the correct link. if you'd have a look at it, i'd be much obliged led and controller

 

[fechter]

OK, that controller doesn't look like it's going to be programmable, so hardware hacks are the best approach.

Does the throttle have to move fairly far before the motor starts moving?

 

[Chalo]

In my experience, there is always a "false positive" phase and Hall wiring combo that makes the motor run too fast, draw too much current, make too much noise, and not provide enough torque. Maybe that's what you're dealing with.

 

[E-HP]

here's the correct link. if you'd have a look at it, i'd be much obliged led and controller

You mentioned the motor is identical. Is the controller identical as well, or did you have a different one originally? A lot of cheap controller have a speed based throttle rather than power based. Speed based delivers maximum power until the motor is spinning at the speed associated with the throttles position. Power based delivers power associated with the position. If the controller are identical, then this shouldn't be an issue.

 

[woofnbike]

nope, the controllers are different. i'm going to go outside and look at a few things ....

 

[woofnbike]

so, yes, the controllers are different, as is the LED. as to being cheap, could be but the package i linked to has been used successfully by people here.

one thing i'm wondering is why the three speed modes are not working -- they're all the same. is that a wiring issue i can correct?

i just took the scoot for another ride and the motor doesn't come to life until i've moved the throttle maybe 1/2" or more. and if i'm very very careful, and feather the throttle just so, then i can get it going at a nice slow sleep. but a sudden twitch of my aging palsied fingers and off i go like a bat out of hell. not good, not to safe either.

i can't help but think that the problem could be solved if i can get the modes working. thoughts? and thanks!

 

[fechter]

No idea why the 3 speed switch isn't working. It looks like it is pre-wired to the display. Does the indicator move when you hit the selector button?
I see there is a "speed limiter" wire (white wire) you can connect to limit the speed. This may or may not help.

The main thing is if you need to advance the throttle 1/2" before it goes, it's in the steep part of the throttle response. The resistor trick will help a lot in this case. You want the motor to start after advancing the throttle just a tiny bit. If you have a different throttle, you might try that first to see if it is better.

 

[woofnbike]

thanks for that. i'll try the white wire limiter and see what that does. meanwhile, if possible, could you give me an amazon link to the appropriate resister ... and perhaps to a different throttle that i might try?

 

[fechter]

Here's a trimmer pot on Amazon:
200 ohm trimmer pots

As far as throttles, they could be all over the map and you'd have to do trial-and-error. I was thinking if you had any other throttles lying around you could just test with one.

The magnet approach is tricky, but can get the same results. The idea is to place a small magnet somewhere near the sensor to tweak the dead band. The motor could suddenly go full throttle when messing around with a magnet, so you have to be sure the wheel is off the ground when testing.

 

[woofnbike]

no other throttles but i ordered the trimmer pot so we'll see how that works in a few days. thanks ....

 

[woofnbike]

okay, this is what i ended up getting. cut the ground wires on the throttle, attached the ends to the middle and righter-most connection points. it does somewhat help the take off to be a bit less herky jerky, which is nice, but the top speed is still the same, way too fast for me. was the thing meant just to even out the take off and, if so, what else can i do to try to limit the top speed? thanks!!!

potentionometer

 

[amberwolf]

If you can't keep yourself from using full throttle by not moving the throttle all the way on, you can use a second pot, preferably 5kohm to 10kohm, wired between throttle and controller: Disconnect only throttle signal wire from controller. One end wire of pot goes to throttle signal out. Other end wire to throttle/controlelr ground. MIddle wire goes to controller throttle input. Now pot scales the throttle voltage to the controller.

If you don't want anything that complicated you could install a physical block to throttle movement beyond whatever position is the max speed you want, but it means you have less movement range for the full speed of the bike, making it a bit harder to get jsut the speed you want.

Using hte pot as noted above scales the voltage so the throttle movement range is still the same but the response is now "finer".

 

[fechter]

Sorry, I misunderstood what you were looking for. I assumed you still wanted full speed. The 3 speed switch might be miswired. You could try measuring the voltages on the wires to see if it looks normal. One wire is typically ground, which is switched to one wire or the other or none to get 3 speeds. There should be something like 5v on the unswitched wire.

Otherwise, you could place another pot or fixed resistor between the throttle and controller that limits the output. There are several ways to do this. You could try a 10k or 20k resistor in series with the signal line. There is usually a pull down resistor inside the controller that will make this work like a voltage divider.

 

[woofnbike]

okay, thanks, all, i will bear down and see if i can't figure this out now, once n for good.

 

[woofnbike]

btw / can you tell me which wires on my controller are the 3-speed switch ones? the pedal assists?

 

[TommyCat]

Does the indicator move when you hit the selector button?
I see there is a "speed limiter" wire (white wire) you can connect to limit the speed. This may or may not help.

Good question and suggestion...

I suspect that when you went with the new controller, it's not configured to communicate or operate properly with your old display.
If they are a matched set, check that the green wire has a good connection from display to controller.

Did you try connecting the two white wires together to limit speed?

As far as the throttle modification, I would recommend the following, with the shown expectations...

This "Double Dipper mod" is shown individually and with more details in this thread under MODIFICATIONS...

Guide to Hall Sensor Throttle operation, testing, and modification.

It would be interesting to see the output voltages of your wayward throttle, when you get things sorted out. But I recommend starting with at least what's happening with the throttle output, before modifying...

Sorry I'm late to the party, but this sounded like a potential different problem.
"the moment i give the throttle a nudge, the motor jerks a few times then smooths out as a higher speed is reached."


Regards,
T.C.

 

[woofnbike]

could the problem be my motor has bad halls, which is does, and the controller/led is made for both hall and without hall and i'm operating without halls? man, i am totally lost, not to mention confused. and dazed.

 

[fechter]

If there is any way to use the halls, it might improve things at startup from a dead stop. Once the motor gets going a little, it shouldn't matter.

Did you ever try the speed limiter wire? I wouldn't be surprised if it makes things worse, but worth a try.

 

[woofnbike]

i'll see about the halls. and will see if i can get at the limiter wire today. maybe order a new throttle from amazon, too, and see if that has an effect.