A light electric stand up scooter

[adrian_sm]

Cycle Analyst is cool, but if you want to go cheap, you can make a simple mod to the servo tester to run a hall throttle.

I have done this, really simple.

viewtopic.php?f=28&t=12196&start=15#p313413

- Adrian.

[ferias77]

Cycle Analyst is cool, but if you want to go cheap, you can make a simple mod to the servo tester to run a hall throttle.
I have done this, really simple.
viewtopic.php?f=28&t=12196&start=15#p313413
- Adrian.

Thanks for the link !!!
I bought the same servo tester but without the aluminium case : http://www.hobbyking.com/hobbyking/stor ... duct=14774
I'm not sure to have well understood, and I would like to be sure...

I remove the potentiometer, I plug my throttle on the power supply of the servo tester, I connect the signal of the hall throttle to the center pin for the potentiometer, and that's ok? It is so simple??? I hope !

Eric

[adrian_sm]

Yep. Pretty simple. Here is a (corrupted) pic of mine.

[ferias77]

Thanks for the photograph Adrian. I will do it asap.
I would like having a thumb throttle and a button for cruise control. I have this button on my e-bike, and it is very usefull for long rides. I think the only one simple solution to have this cruise control is the cycle analyst, no?
I made other tests with my scooter to be sure it is ok. And no... Starting full throttle, I have to push on the handlebar, otherwise the front wheel stands up !!!
And I finished by coming to the limits of the machine : the pressure screw between the motor and the small sprocket in not enough. I have to work on this. I will too order a 35 teeth sprocket to limit the top speed : 26 km/h will be enough, 37 km/h is really too much. So there will be more torque during the start...

[adrian_sm]

You should be able to add a button fairly easily to hold it at a specific throttle posistion, ie full throttle. A momentary push button and a resistor should do the trick.

I have also used this little guy to smoothly ramp up the throttle, for a push button input. I just plugs in between the servo tester and the ESC. This was great for implementing a push button as a throttle, without flipping the bike.

http://www.hobbyking.com/hobbyking/stor ... oduct=8863


I have also got an Arduino based throttle interface I am working on. Just in the debugging phase at the moment.

It accepts a button input as the throttle, has a power or speed PID loop (users selectable on the fly via the button), a turbo mode, SD data logging, LCD display (speed, power, dist, wh/km etc), temp sensor, wheel sensor, voltage, current... can't remember what else. This is being purpose built for my frcition drive project, but it is looking like it will be very usefull for other applications too. : ) Not ready for release yet, but it is looking really good.

- Adrian

[ferias77]

Hi,

I bought this Turnigy speed regulator with my motor, but I don’t have tested it yet. I thought to a problem : it smoothly ramps up the throttle, but it smoothly ramps up down too, no? If it is the case, it is very dangerous… There is a solution?
For the button, I will try to draw something.

Eric

[adrian_sm]

Np. There is separate adjustment for up and down. So no problem.

Just try it on the bench first.

- Adrian

[fechter]

Great job on the scooter!

How hot does the motor get?

[ferias77]

Np. There is separate adjustment for up and down. So no problem.
Just try it on the bench first.
- Adrian

I tried it this evening, really great ! As it works, I won't need any thumb throttle : I will try with only a push button and a potentiometer to choose the top speed.

Great job on the scooter!
How hot does the motor get?

I didn't ride for a very long trip but I made a lot of stop and starts, and I think the motor temperature was about 35°C. Not too warm to the touch, but I don't have any thermometer. Peak Power was 1900W

Eric

[adrian_sm]

I will try with only a push button and a potentiometer to choose the top speed.

If you want this sort of setup. I would keep the standard servo tester, and use that to set the top speed. Then cut the 5V leg on the pot in the servo tester and put your button in the break. Then I think you need to add a pull down resistor between the signal leg of the pot and ground, so it makes sure it goes to zero when you let go off the button. Then off course use the speed regulator thing.

That should do the trick.


Oh. I have been meaning to ask. How on earth do you stop? Only brakes I saw in your video was your foot. That almost scares me as much as using teh servo tester on it's own as a throttle.

I still have a nagging urge to build one of these... urrgggh... must finish other projects first.

- Adrian

[ferias77]

If you want this sort of setup. I would keep the standard servo tester, and use that to set the top speed. Then cut the 5V leg on the pot in the servo tester and put your button in the break. Then I think you need to add a pull down resistor between the signal leg of the pot and ground, so it makes sure it goes to zero when you let go off the button. Then off course use the speed regulator thing.
That should do the trick.

I thought doing like that (I used your photograph, I hope it isn't a problem, otherwise I remove it) :



For example, if the potentiometer is 10 kOhm, U1 = 0.9 V and top speed = 5.4 km/h.
If the potentiometer is 0 kOhm, U1 = 5V and top speed = 30 km/h

It would be more simple with you solution. But I want to change the potentiometer of the servo tester to have the possibility to screw it on a mount. And it is hard to find a 5K potentiometer. 10K is more common. I don't understand very well the pull down resistor?

Oh. I have been meaning to ask. How on earth do you stop? Only brakes I saw in your video was your foot. That almost scares me as much as using teh servo tester on it's own as a throttle.

For the brake, I didn't mount it, but it will be the case for the next ride ! You're right, it is dangerous...

I still have a nagging urge to build one of these... urrgggh... must finish other projects first.
- Adrian

So I hope you will finish other projects asap !

[adrian_sm]

The pull down resistor is needed to make sure that when the throttle button/switch is open, that the U1 =0V. Otherwise it is floating, and current leakage in the PCB can make it go positive. So even without the button pressed, you can get a throttle signal causing the motor to start. Not good.

Just place your switch on the red 5V line at the top, not the black 0V line on the bottom, and R1 will act as the pull down resistor.

Too easy.

- Adrian

[ferias77]

The pull down resistor is needed to make sure that when the throttle button/switch is open, that the U1 =0V. Otherwise it is floating, and current leakage in the PCB can make it go positive. So even without the button pressed, you can get a throttle signal causing the motor to start. Not good.
Just place your switch on the red 5V line at the top, not the black 0V line on the bottom, and R1 will act as the pull down resistor.
Too easy.
- Adrian

Ok, thanks, perfect ! I will order the components and test it asap !

The new push button circuit :


Eric

[Grinhill]

Nice work Eric. BTW - Is there something wrong with your video, I couldn't play it????

And I finished by coming to the limits of the machine : the pressure screw between the motor and the small sprocket in not enough.

This is a fairly common problem, and the best solution found by recumpence and other forum members seems to be drilling a "dimple" into the shaft a few millimetres deep at the position marked by the grub screws. Works better than filing flats onto shaft. Also, on final assembly don't forget to use some Loctite thread locker on the grub screws.

[ferias77]

Nice work Eric. BTW - Is there something wrong with your video, I couldn't play it????

And I finished by coming to the limits of the machine : the pressure screw between the motor and the small sprocket in not enough.

This is a fairly common problem, and the best solution found by recumpence and other forum members seems to be drilling a "dimple" into the shaft a few millimetres deep at the position marked by the grub screws. Works better than filing flats onto shaft. Also, on final assembly don't forget to use some Loctite thread locker on the grub screws.

Yes, we have the same idea, I did it yesterday. I hope it will be enough...

For me, the video works very well. There was maybe a problem when you tried. Please try again and tell me if it works.

Eric

[Grinhill]

video worked fine, must have been a problem on my end before. Thanks.

[ferias77]

I tested the repaired scooter and now it works very well ! I will test it longer this week end.
Now I would like to put a freewheel on the wheel sprocket. This freewheel must be very thin : 12mm maximum. Do you know where I could find it ? I don't find...

Eric

[rodgah]

Excellent little project you have there.

Now I would like to put a freewheel on the wheel sprocket. This freewheel must be very thin : 12mm maximum. Do you know where I could find it ? I don't find...

none that i have seen would fit. Though would you consider a freewheeling motor sprocket? You might have to install a larger wheel sprocket to keep your reduction the same ratio but these can be bought at http://www.electricscooterparts.com/sprockets.html



cheers.

[ferias77]

Thanks for your comment and for the link. I know this freewheel, it would be a very good solution. But the problem is that there are 15 tooth. If I want the correct gear ratio, the big sprocket will be bigger than the wheel... I will continue to search. if you have any idea, don't hesitate.

This week end, I made a 21.1 km ride with my scooter. It works really very well (if the asphalt is correct, of course), I'm very happy with it. There were a lot of starts and stops, I was on the town. Riding between 15 and 31 km/h (Mean speed = 19.6 km/h), I used 193.1 Wh for the 21.1 km, so 9.15 Wh/km, almost what I expected. Tomorrow, I will try to go to work with it, we will see how it goes to replace my ebike. I have 23km / day to go to work.

Eric

[Grinhill]

Wow, 23km would be a huge ride on a scooter. Even if the machine is up to the task, there might be fatigue issues with your body! You would get a lot more vibration than on an e-bike, and your arms and legs may also get tired from holding the same position.

On the plus side, if you have a failure it would be very easy to jump on a bus and carry your scooter with you.

Good Luck!

[ferias77]

Wow, 23km would be a huge ride on a scooter. Even if the machine is up to the task, there might be fatigue issues with your body! You would get a lot more vibration than on an e-bike, and your arms and legs may also get tired from holding the same position.

I tried this morning : first ride to go to work, and it is ok. It is 23 km / round trip, so 11.5 km / trip. It's enough confortable. Just the 100 last meters where the asphalt is too bad, but I can walk on this little distance.
No problem with the hills, it is very powerfull. I used 129.5 Wh, so 11.3 Wh/km.

On the plus side, if you have a failure it would be very easy to jump on a bus and carry your scooter with you.
Good Luck!

I agree : this morning I went to work very early, hoping a colleague could carry me and my scooter if the scooter breaks down... but it was not necessary !

Eric

[cwah]

I waaaaant one. But I'm completely newbie and never assembled anything. Do you know if I could do it?

[ferias77]

I waaaaant one. But I'm completely newbie and never assembled anything. Do you know if I could do it?

Yes, for sure you could do it. You just have to read carrefully to have all the information, and take your time.

Eric

[cwah]

Thanks for your answer. I'm sure I'll need time because I don't have knowledge whatsoever.

I want for sure to have something like this. However it's forbidden in UK public road. The best would be to hide the motor so people won't have any suspicion. (and I don't want to get arrested by police)