eBike obsessed!

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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Sun May 10, 2020 7:38 am

This guy went through some shit getting this bike up & running. But, he documented everything and will be a good resource for others trying to import a bike from china and/or build something that actually has some decent performance. Massive hub motor won't make this thing killer in the corners, but for blasting around town or commuting, it should be really good for a bike that can be built for less than $6000... Start with a used sportbike, and that number would come way down, too.






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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Sun May 10, 2020 7:55 am

DerGolgo wrote:
Tue Apr 28, 2020 1:39 am
The thought just occurred to me that, in a brushless DC motor, the frequency at which the windings are switched would be a relevant variable. Is that how all of it is done, and electricity is drained from the battery just however it comes out?
I don't really know how the circuitry works. The battery cables +/- go into the motor controller. The throttle wires also connect to the controller. Electrickery happens inside the box. The controller outputs to 3 phase wires. They connect to the 3 phases of the BLDC motor.
With the programmable controller, all I can vary are the amps. I can set how many amps are drawn from the battery. And I can set how many amps are pushed out to the phase wires. Its usually around 2:1. With a battery pulling 100A, you'd typically push 200A to the phase wires. If your motor doesn't get hot, you can push more phase amps. If the motor heats up too quickly, you would reduce the phase amps. Battery amps would be increased or decreased based on heat and also voltage sag. If your battery heats up or the volts sag too much, you'd reduce the battery amps. Or, ideally, build a bigger battery that can handle the stress.
DerGolgo wrote:
Tue Apr 28, 2020 1:39 am
Also, I'm still curious as to heat management. I assume that, be they water or air cooled, motors and controllers come with temperature sensors to let the controller avoid excessive temperature buildup in those components.
However, batteries, too, get warm. Quite warm, if considerable current is drawn.

Is the maximum amperage that the controller allows set so low that overheating isn't a problem to begin with, or is there another cooling mechanism?
Most automotive applications have active cooling (and sometimes heating) of the battery pack and motor. Most motorcycle applications like Zero, don't and DIY ebikes don't. In those situations, you appropriately match the battery size and current output to keep the heat under control. If you follow the spec sheets of your batteries, you should be able to build an appropriate battery that won't overheat. A samsung 25r can take 20A continuously, for example. If you make that the limit in your controller programming, your battery will be fine. Also, yes, most controllers and motors these days have temp sensors in them and you can set your controller to reduce power if heat rises.

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DerGolgo
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Re: eBike obsessed!

Post by DerGolgo » Sun May 10, 2020 2:57 pm

problemaddict wrote:
Sun May 10, 2020 7:55 am
With the programmable controller, all I can vary are the amps. I can set how many amps are drawn from the battery. And I can set how many amps are pushed out to the phase wires. Its usually around 2:1. With a battery pulling 100A, you'd typically push 200A to the phase wires.
Huh. Most circuits I've met might limit how many amps can be drawn without a voltage dropoff. Pushing amps into a circuit that's not drawing them doesn't quite match what they taught me at uni, or what I've learned myself since.

But there might be stuff going on here I'm not familiar with. Probab... Almos... Certainly is.

Upping the Amps like that would require either increasing the voltage or reducing the resistance in that circuit. Old man Ohm doesn't tolerate much else.
Based on what you described about that shunt, I'm inclined to think there is jiggery, and pokery, with some kind of balast in that circuit.
Basically just a set of resistors regulating how much current the motor circuit can draw.

However, since you've actually worked with that stuff, and you seem to be getting along, all this is unqualified academic speculation on my part.
problemaddict wrote:
Sun May 10, 2020 7:55 am
A samsung 25r can take 20A continuously, for example. If you make that the limit in your controller programming, your battery will be fine. Also, yes, most controllers and motors these days have temp sensors in them and you can set your controller to reduce power if heat rises.
Hehe. I've actually used 25Rs for a while, vaping. I retired them as they failed, one by one, and replaced them with Sonys.
They do get warm, even if you stay below the rated continuous discharge current. You notice that if you're holding a pair of them in your hand. But they won't get hot, indeed. Passively cooling should be plenty there.
If there were absolutely anything to be afraid of, don't you think I would have worn pants?

I said I have a big stick.

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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Mon May 11, 2020 5:28 pm

Pushing, pulling, drawing ... I'm sure my terminology is wrong as well. The motor is drawing the currents from the battery by trying to overcome inertia, friction, and aero. The numbers I was referencing, 100A battery and 200A Phase, are *limits* you set in the controller settings. So, if you're riding on flat ground at a slow speed, the system won't be pulling 100A from the battery. But, if you're trying to go uphill at WOT into a headwind, the motor will be limited by the controller to only pull 100A.

Does that make more sense?

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DerGolgo
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Re: eBike obsessed!

Post by DerGolgo » Tue May 12, 2020 1:25 am

problemaddict wrote:
Mon May 11, 2020 5:28 pm
Does that make more sense?
That makes a lot more sense, actually.

Now that I think about it. Phases. I've only ever encountered those in rotating-current affairs, AC stuff. Like the three-phase I've got on my water heater, while I'm getting single-phase out of the normal outlets.
DC motors tend to have a + and a -. Reskimming your earlier description, you're running your motor on 3 phase AC?
Entirely plausible. Would require an inverter in that control box, but entirely plausible.

Googling on about it, turns out, AC drive is apparently becoming popular in rail traction. The advantage being that the traction effort produced, determined by the torque the motor puts out, can be regulated by regulating the frequency that the motor is fed with. While in simpler DC motors, the torque produced depends far more on motor speed and resistance, which wouldn't be so stable.

So that would play nice re your description about limiting torque. When torque isn't directly related to what the motor is being fed by the control box, but depends on motor speed, I'd imagine limiting might be a limited approach.

And my question about how throttle is being done would also be answered. By the frequency that is being fed into the motor is how, from a variable-frequency inverter. AKA Variable-Frequency Drive, which appears to have become very popular with the arrival of solid-state switching technology that, in turn, made the technology possible without resorting to a rotating bit in the control mechanism.

Polyphase induction motors (more than one phase) are also self-starting, so no need of that nonsense like with the electric fans that have to switch OFF-High-Mid-Low, because the starting torque with a single phase induction motor is so little, it must switch to high to get moving at all, and not burn out the motor by standing still while all that current is flowing, heating up the windings.

So I'd guesstimate the motor you have there is an Poly-/3-phase AC Induction motor. Which are so reliable, their service life is limited by the service life of the bearings the shaft spins in. And since motor speed, and torque, are governed by frequency, would (I'd assume) be less vulnerable to lessening voltage.

Does this ramble sound plausible, @problemaddict ?
If there were absolutely anything to be afraid of, don't you think I would have worn pants?

I said I have a big stick.

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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Tue May 12, 2020 3:09 am

While it's three phases, its still DC going into the motor. This comes up now and again in the ebike forums, but I always forget the specifics. Here's an article I found:
In BLDC motors, the stator coils are wound trapezoidally, and the back-EMF produced has a trapezoidal wave form. Because of their trapezoidal waveform, direct current is required in order to get the best performance form BLDC motors. In contrast, synchronous AC motors are wound sinusoidally and produce a sinusoidal back-EMF, so they require sinusoidal drive current in order to achieve the best performance.
https://www.motioncontroltips.com/faq-w ... ac-motors/

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0l4fderstout
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Re: eBike obsessed!

Post by 0l4fderstout » Tue May 12, 2020 6:44 am

DerGolgo wrote:
Tue May 12, 2020 1:25 am


Googling on about it, turns out, AC drive is apparently becoming popular in rail traction. The advantage being that the traction effort produced, determined by the torque the motor puts out, can be regulated by regulating the frequency that the motor is fed with. While in simpler DC motors, the torque produced depends far more on motor speed and resistance, which wouldn't be so stable.
In HVAC/R we're seeing Frequency drives moving into more mainstream applications. It's always running at some level, but by adjusting the frequency of the electricity, it can meet demand smoothly. Things are getting interesting out there.

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DerGolgo
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Re: eBike obsessed!

Post by DerGolgo » Tue May 12, 2020 7:51 am

problemaddict wrote:
Tue May 12, 2020 3:09 am
While it's three phases, its still DC going into the motor. This comes up now and again in the ebike forums, but I always forget the specifics. Here's an article I found:
Okay. So rather than the voltage going positive and negative again, no matter what you do, the DC current just has the polarity switched in discrete increments. The kind of thing transistors are good at.

That makes a lot more sense now, I think I'm starting to get it. This would also allow to throttle with frequency, I'd guesstimate. Which would basically be just like pulse-width modulation, only that the polarity of each pulse is flipped.

Personally, since the polarity is what keeps changing, I'd still describe that as alternating current. Yeah, you shove direct current into the control box. But the control box makes it not-direct current.
But I guess if the industry has decided to call that DC, I'd guess to avoid misunderstandings when non-technical types are told that the motor eats DC, but works with AC, then I won't die on that hill.
If there were absolutely anything to be afraid of, don't you think I would have worn pants?

I said I have a big stick.

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Bigshankhank
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Re: eBike obsessed!

Post by Bigshankhank » Wed May 13, 2020 6:51 am

So all of this is too much thinking, so the idea of trying to build a kit for the 'Macchi will take a back burner. Sadly I was unable to snag one of my spare bicycles from home but I will be back there in a few weeks time and will aim toward buying an electric hub w/ controller kit and a small battery and just make a little knock-around bike to conquer some hills up here.
It's time for Humankind to ditch the imaginary friends of our species' childhood and grow the fuck up.
-Davros

"Lasse mich deine Seele dem Herrscher der Finsternis opfern"

Let me sacrifice your soul to the ruler of darkness

Always carry a bottle of whiskey when you travel in case of a snakebite. Futhermore, always carry a small snake.

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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Thu May 28, 2020 8:42 am

Hank, for future reference, heres a channel i just discovered. He,s built a 70s kawa kz400 with a real simple setup. Hes gettimg 65mph on an older-school controller. (a better controller would have whats called "field weakening" which would allow for 10-20% more top speed). 40mi range i think he said (in eco mode), but he's only using a 3.6kwh battery, and as you'll see he's gott room for at least double that batt size.

https://www.youtube.com/channel/UCAhZWZ ... 4Pw/videos




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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Thu Jun 04, 2020 5:53 am



eBikes are dangerous! 😜

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Bigshankhank
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Re: eBike obsessed!

Post by Bigshankhank » Thu Jun 04, 2020 9:59 am

I saw that on insta, WTF happened?
It's time for Humankind to ditch the imaginary friends of our species' childhood and grow the fuck up.
-Davros

"Lasse mich deine Seele dem Herrscher der Finsternis opfern"

Let me sacrifice your soul to the ruler of darkness

Always carry a bottle of whiskey when you travel in case of a snakebite. Futhermore, always carry a small snake.

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Jaeger
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Re: eBike obsessed!

Post by Jaeger » Fri Jun 05, 2020 8:51 am

Yeah, I think I saw something about awkward x-rays on FB. WTF you do?

--Jaeger
Bigshankhank wrote:The world is a fucking wreck, but there is still sunshine in some places. Go outside and look for it.
<<NEUTIQUAM ERRO>>
2018 Indian Scout -- "Lilah"

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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Sat Jun 06, 2020 7:10 pm

Well, you guys know this bike is twitchy & I'm not sure I ever had it turned up to full power at Doom. So, I went out with all the (virtual) knobs turned up to 11 to record a final top speed. Full power is 7.2kw which is around 10hp.
It takes full concentration to ride at that power, & I lost concentration for a sec. Something caught my eye, & I turned my head around to check behind me & that was enough to upset the bike, start a death wobble & the bike flipped out from beneath me.
It wasn't a very violent crash. I feel on my right side but I somehow broke my left wrist.
Watching the video, it looks like maybe my helmet came down & smashed my wrist into the pavement.

So there ya go. Lucky me. Two broken bones in 6 weeks....

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DerGolgo
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Re: eBike obsessed!

Post by DerGolgo » Sun Jun 07, 2020 11:11 am

problemaddict wrote:
Sat Jun 06, 2020 7:10 pm
I feel on my right side but I somehow broke my left wrist.
Watching the video, it looks like maybe my helmet came down & smashed my wrist into the pavement.

So there ya go. Lucky me. Two broken bones in 6 weeks....
:o :shock: DON'T DO THAT!

I take it traumatic brain injuries have been ruled out?
If there were absolutely anything to be afraid of, don't you think I would have worn pants?

I said I have a big stick.

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Jaeger
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Re: eBike obsessed!

Post by Jaeger » Mon Jun 08, 2020 6:41 am

problemaddict wrote:
Sat Jun 06, 2020 7:10 pm
Well, you guys know this bike is twitchy & I'm not sure I ever had it turned up to full power at Doom. ...

So there ya go. Lucky me. Two broken bones in 6 weeks....
Jayzus! Yeah, damn right those bikes are twitchy! Glad it wasn't worse, but yikes!

--Jaeger
Bigshankhank wrote:The world is a fucking wreck, but there is still sunshine in some places. Go outside and look for it.
<<NEUTIQUAM ERRO>>
2018 Indian Scout -- "Lilah"

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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Tue Jun 09, 2020 6:29 am

DerGolgo wrote:
Sun Jun 07, 2020 11:11 am
I take it traumatic brain injuries have been ruled out?
I'm not sure anyone would notice a difference! 😀

But, no signs of anything. I didn't black out, no headaches, etc. I think the helmet did it's job...

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boz
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Re: eBike obsessed!

Post by boz » Thu Jun 18, 2020 9:57 am

problemaddict wrote:
Sat Jun 06, 2020 7:10 pm
Full power is 7.2kw which is around 10hp.
Heal up! But gotta say wow to 7200W. I have a 2000W full suspension ebike and it's heavy at 80lbs and still feels fast at 35mph...also goes to show how much more power is required to at 20mph at what I assumed is less than half the weight?
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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Fri Jun 19, 2020 6:27 am

boz wrote:
Thu Jun 18, 2020 9:57 am
Heal up! But gotta say wow to 7200W. I have a 2000W full suspension ebike and it's heavy at 80lbs and still feels fast at 35mph...also goes to show how much more power is required to at 20mph at what I assumed is less than half the weight?
Yeah, the power is FUN. I think the bike weighs 65lbs. Its an all-steel bike with real motorcycle tires & the hub motor is 20+ lbs alone.

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problemaddict
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Re: eBike obsessed!

Post by problemaddict » Thu Jun 25, 2020 6:23 am

No Gas Vespa.jpg
Sweet little retro clone.

From here https://www.go2roues.com/shop/2twenty-roma/, but i'm sure also available direct from:
comesfromCHINA.gif
:mrgreen:
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