My Electric Motorbike

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Dui, ni shuo de dui
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My Electric Motorbike

Post by Dui, ni shuo de dui » Aug 14, 2017 10:47 pm

Hello everyone,

A little topic to present my new e-motorbike.

Specs:
-Motor: QS 3000W V3 High speed version
-Controller: Currently tested: Yuyang King 100 Amps, Sabvoton 150 Amps and Sabvoton 200Amps (battery continuous draw)
To be tested soon: Kelly 12401, 120V (200Amps continuous)
-Battery: SLA 72V 35Ah

Performance:
-top speed: 115kmh
-Acceleration from 0-100: not tested yet, but probably around 8 seconds
-Range: about 40-50 km while riding agressively

I've purchased it a week ago, already changed the original yuyang king controller. Currently, the 150A sabvoton is installed in the machine and gives very decent performance and I'll test the Kelly very soon.
It's a pretty decent machine, the battery could be lighter of course since it is SLA, lithium being a bit too much expensive for me at this time. So far I'm pretty satisfied with it.

In a near future, I'll probably swap the motor for a high torque version and go for at least 96V to compensate for speed loss.

Anyway, a few pics of the beast:
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The whole machine is covered in 3D carbon film, which looks beatiful, and of course makes it faster
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The original Yuyang King 100A controller... It was quite underpowered...
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The 150A Sabvoton, much better but still not great, because of the machine's heavy weight
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The 200A sabvoton, quite powerful, I think it now has similar or slightly better performance than the original gas engine
IMG_4216.JPG
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Changing the fried front bearings:
IMG_4212.JPG
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I think this machine has a lot of potential, the frame is pretty lightweight, it handles great, there is plenty of space for the battery, according to my taste it looks gorgeous and the suspension is quite comfortable, at least much more than my scooter's.
I just hope I'll be able to convince myself to invest on a big lithium battery, but I don't really get all the battery management system part, especially when it comes to very high power settings. I would love to build my own 120V lithium battery for this, using prismatic cells. Just no idea how to make it safe for now.

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macribs
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Re: My Electric Motorbike

Post by macribs » Aug 27, 2017 12:34 am

Nice. What model is that bike originally?

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Re: My Electric Motorbike

Post by Dui, ni shuo de dui » Aug 27, 2017 8:32 pm

macribs wrote:Nice. What model is that bike originally?
I don't really know. Seems to be a Chinese 250 or 150 cc motorbike, I don't think it has been copied from any japanese model (at least, not 100% copied, but it looks very similar to the Kawasaki Ninja 250)
IMG_4222.JPG
IMG_4222.JPG (208.08 KiB) Viewed 1188 times

swiftyds
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Re: My Electric Motorbike

Post by swiftyds » Oct 24, 2017 6:37 am

I've been looking at importing one of these Chinese electric motorcycles into the UK. Can you tell me what the model is of yours?

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Re: My Electric Motorbike

Post by Dui, ni shuo de dui » Nov 16, 2017 4:05 am

swiftyds wrote:I've been looking at importing one of these Chinese electric motorcycles into the UK. Can you tell me what the model is of yours?
Lol, I would, but as I just said earlier: I have no idea XD

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Re: My Electric Motorbike

Post by John in CR » Nov 19, 2017 1:57 pm

You will accomplish exactly nothing by swapping to a slower wind version of the same motor. "High torque versions" are absolute myth. The reason is the windings are longer and thinner copper, so they handle proportionately less current for the same amount of heat, and heat is our hubbies' true limitation.

If you change your existing motor to a smaller outside diameter wheel and up the voltage, then you will have accomplished something that gives you greater performance.

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Re: My Electric Motorbike

Post by Dui, ni shuo de dui » Nov 19, 2017 10:42 pm

I'm not sure what makes you think that torque motor is "a myth".
I tried various versions of QS motors, torque/balanced and speed and I can tell you that there is a difference, both in torque, speed and power consumption.

Changing my motor for a smaller diameter is really not an option, since it would totally ruin the bike's balance by making it lean on the rear wheel. It would look very weird, give a lower ground clearance and affect the handling.

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Re: My Electric Motorbike

Post by macribs » Nov 20, 2017 12:36 am

You might wanna consider taking John's advice. He knows.

I noticed you got SLA batteries. If you swap that battery for a proper e-battery you probably would have both lighter weight and faster discharge times. Meaning your battery can deliver more current faster to the controller and in the end to the motor. You could look into either hi qual li ion cells like 30q from samsung or VTC5/6 from sony. Or be adventures and have a look for lipoly. I am not dead certain on the SLA performing thingy, but that could sure be something to look into and gather more info.

Probably better putting money into where you get a better return then spending money on yet another motor just with different winding.

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Re: My Electric Motorbike

Post by Dui, ni shuo de dui » Nov 20, 2017 1:07 am

macribs wrote:
Nov 20, 2017 12:36 am
You might wanna consider taking John's advice. He knows.
Well, maybe. But that's just not what I experienced. Anyway, I don't think I'll do that just yet, I've got other plans :)
macribs wrote:
Nov 20, 2017 12:36 am
I noticed you got SLA batteries. If you swap that battery for a proper e-battery you probably would have both lighter weight and faster discharge times. Meaning your battery can deliver more current faster to the controller and in the end to the motor. You could look into either hi qual li ion cells like 30q from samsung or VTC5/6 from sony. Or be adventures and have a look for lipoly. I am not dead certain on the SLA performing thingy, but that could sure be something to look into and gather more info.
SLA have a great discharge rate, at the expense of the capacity. I could have a bit more performance swapping to lithium in terms of acceleration, but that would mainly come from the weight loss.
About lithium, the only option I would consider is LiFePo4. I use my machine everyday to go to work, charge it overnight, so I don't want to take any chances with fire hazard (I've seen many ebikes burn and had a few friends who had pretty big fires using Li-ion and Li-Po). Plus they are way more reliable on the long run.
macribs wrote:
Nov 20, 2017 12:36 am
Probably better putting money into where you get a better return then spending money on yet another motor just with different winding.
Well, that's not really the same kind of money. A new motor costs about 2000 rmb. A decent battery would cost at least 10 000.
But yes, I'm looking into this. Actually, I would like to build my own battery, but I cannot find a really good thread about BMS systems. I would need to build one from scratch since Chines BMS are notoriously unreliable, but I havent' seen any good tutorial about that. I wonder if this could be done with an Arduino and a few components, never seen anything like that yet but that would be great.

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Re: My Electric Motorbike

Post by John in CR » Nov 20, 2017 5:53 am

You noticed changes because you didn't make all changes needed for a fair comparison. The torque limits of a motor are based on it's steel and magnets. How the copper is wound only changes the voltage and current to get there. So-called "torque" versions are simply wound to a lower Kv. While that gives you increased torque per amp, it proportionately decreases the amp limit, so it puts you back in the same place in terms of power except that you have to use a higher voltage to get there.

If you want to mod your bike for greater performance, then make motor cooling modifications so you can run higher power at the same temperature.

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Re: My Electric Motorbike

Post by macribs » Nov 20, 2017 2:30 pm

Stubbornness rarely trumps science, I know as I time and time again started down the samt path. Add that money and they money spend on wrong parts, either by rush impulse trading online, or by trusting an old brain for measure/size and order based on sa(i)d memory and I am certain I could have a very decent ready made fully assembled e-bike delivered to my door.

And if you look around the forum you will find many other people who also started down the same road you are about to embark upon, swapping to "hi torque". After considerable money spending, time wasted etc most do change their minds in the end and trust what others have tried before them.

SLA might have great discharge rate for all I know, but they are bulky and heavy as a motherfcuker. For the same volum of batteries you could fit larger li ion battery and save weight. Even higher discharge and lighter weight now that is a win. Lifepo is very 2013. There are thousands of bev's from bikes to scooter/motorcycle to cars, buses and trucks running day after day for a decade without fire hazard. Main thing is to monitor and manage the charging, discharging and have a correct working bms or controllers to cap high voltage and low voltage. Never charge to 100% try to charge to 80-85 % and never drain battery completely and you will be sorted.

Have a look at this great source for diy battery building, written by an es member; https://www.amazon.com/DIY-Lithium-Batt ... on+battery

I know li ion batteries are expensive, but could you possible find salvaged Tesla cells, or maybe second hand Nissan Leaf cells? Look at it this way. Battery cost is something we all struggle with. And sometimes we just don't have the money for it. Now you got a well working SLA, try sell off the SLA. IF you are lucky you get some dineros for the SLA. Don't spend that 2000 rmb on a new motor. Say you can score used Tesla cells for 6000 rmb, maybe you can get 1000-2000 rmb for your SLA battery and factor in that 2000 rmb you save for not getting a new hi torque motor. Possible you can also get some change by selling two of your controllers. If you are lucky you can spend 2K on a new motor or 3-4000 on a better battery.

If battery is no go at this time, by bigger motor or maybe even mid drive rather then buying more of the same expecting new results.

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Re: My Electric Motorbike

Post by John in CR » Nov 20, 2017 9:26 pm

Once you go lithium, you'd never even consider going back to lead batts.

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Re: My Electric Motorbike

Post by Dui, ni shuo de dui » Nov 20, 2017 10:16 pm

macribs wrote:
Nov 20, 2017 2:30 pm
Stubbornness rarely trumps science, I know as I time and time again started down the samt path.
Stubborness means that someone would persevere in the same path with no regards to whatever suggestions or facts other people are presenting.... I just said that I changed my mind and won't change my motor in the previous post. So I'm not sure being the stubborn one there. XD

macribs wrote:
Nov 20, 2017 2:30 pm
And if you look around the forum you will find many other people who also started down the same road you are about to embark upon, swapping to "hi torque". After considerable money spending, time wasted etc most do change their minds in the end and trust what others have tried before them.
I know that swapping my motor for a high torque would help me to get a better 0-30km/h acceleration. I was not asking for directions there, it is just a fact. If I don't change anything to my configuration and replace my motor for a torque version, I will have a bit more startup power. I've done a lot of electric scooters, helped countless people to build their own, so I know what I'm talking about.
John is theoretically right: If I would ever reach the current limits of my motor, this limit would be lower with a torque motor. Indeed. That is absolutely true. But the fact is: my controller doesn't reach the motor limits just yet. The motor barely got to 70 degree C during the hottest days of summer, after long aggressive rides. In addition, my current motor seems to be a V2, changing would allow me to go for a V3 which have more beefy wires used for the windings. Hence, higher limit. Not mentionning I could go for a watercooling system, it's super easy to build.

Anyway, I'm not a complete noob on the subject, what John says is right, but he doesn't take into account my actual situation.
macribs wrote:
Nov 20, 2017 2:30 pm
SLA might have great discharge rate for all I know, but they are bulky and heavy as a motherfcuker. For the same volum of batteries you could fit larger li ion battery and save weight.
That's what I would like to do at some point. But this is actually an area of which I'm quite a noob: building a BMS system.
If I ever manage to understand how this thing is supposed to work in details, I would for sure build my own battery. So far I completely understand the theory, but I struggle when it comes to what actual components to use to build one from scratch (since here, in China, it is nearly impossible to find BMS able of handling more than 150 Amps. Plus I don't really trust their BMS).
macribs wrote:
Nov 20, 2017 2:30 pm
Lifepo is very 2013.
Maybe. Yet it is safe, stable, relatively inexpensive and has a very long lifespan.
The only issue is that it is a bit heavy and that the C-rating is not the highest, but my goal is not to build a racetrack machine to ride side to side with Valentino Rossi, but simply to get about 60-80km of range, have a bit less voltage sag during the acceleration to slightly improve performance, and finally, be able to charge it every night without being burned to death.
macribs wrote:
Nov 20, 2017 2:30 pm
There are thousands of bev's from bikes to scooter/motorcycle to cars, buses and trucks running day after day for a decade without fire hazard. Main thing is to monitor and manage the charging, discharging and have a correct working bms or controllers to cap high voltage and low voltage. Never charge to 100% try to charge to 80-85 % and never drain battery completely and you will be sorted.
BMS and chargers are not 100% fail safe. I've seen some of them failing at monitoring cells properly, which ended up in fire.
Even some very experienced people here had issues with "state of the art" protection systems.
I don't need and I don't want to take any chances. I prefer a proven safe technology, even if it means less performance.
Here in China, we don't have fancy insurances and stuff to cover our asses whenever something goes wrong. So If I burn down my house, I have to pay all my life for that. It just doesn't worth it.
macribs wrote:
Nov 20, 2017 2:30 pm
Have a look at this great source for diy battery building, written by an es member; https://www.amazon.com/DIY-Lithium-Batt ... on+battery
Thanks, I'll have a look at it :)
macribs wrote:
Nov 20, 2017 2:30 pm
I know li ion batteries are expensive, but could you possible find salvaged Tesla cells, or maybe second hand Nissan Leaf cells? Look at it this way. Battery cost is something we all struggle with. And sometimes we just don't have the money for it. Now you got a well working SLA, try sell off the SLA. IF you are lucky you get some dineros for the SLA. Don't spend that 2000 rmb on a new motor. Say you can score used Tesla cells for 6000 rmb, maybe you can get 1000-2000 rmb for your SLA battery and factor in that 2000 rmb you save for not getting a new hi torque motor. Possible you can also get some change by selling two of your controllers. If you are lucky you can spend 2K on a new motor or 3-4000 on a better battery.

If battery is no go at this time, by bigger motor or maybe even mid drive rather then buying more of the same expecting new results.
Plan was to change both. But yeah, first priority would be the battery. For the motor, that was just to improve a bit the starting torque, but I would lose quite a bit of speed, which, as it turns out, I'm pretty used to now.

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Re: My Electric Motorbike

Post by Dui, ni shuo de dui » Nov 20, 2017 10:42 pm

John in CR wrote:
Nov 20, 2017 9:26 pm
Once you go lithium, you'd never even consider going back to lead batts.
It depends.
I have a huge 72V 50Ah lithium battery on my electric scooter. It is nice, but it could not handle the current demand for a continuous 200Amps controller without cutting instantly.
I'm currently at the very limit of this battery using a 150A sabvoton. If I push it to 160A the battery would cut.
You don't have that kind of problems with SLA, it just lags and reduces your range and perfs.

Also, SLA are dirt cheap and easy to work with.
So it really is a matter of compromizes. For a high perf, dirt cheap, low range machine it may be a nice choice.

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Re: My Electric Motorbike

Post by John in CR » Nov 22, 2017 12:12 am

High performance and lead simply don't belong in the same sentence. Regarding some low power craptastic lithium scooter pack, I wouldn't waste my time. I use automotive grade cells to build my packs, so I get safety, high power, long life, and low price all in one package. In the long run the lithium I use is more economical than the cheap lead anchors you want, so there's no upside to those toxic lead batteries that a polluting China so badly now.

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Re: My Electric Motorbike

Post by Buk___ » Nov 22, 2017 12:30 am

John in CR wrote:
Nov 22, 2017 12:12 am
I use automotive grade cells to build my packs, so I get safety, high power, long life, and low price all in one package.
Where do you buy your "automotive grade cells"?
John in CR wrote:
Nov 22, 2017 12:12 am
there's no upside to those toxic lead batteries that a polluting China so badly now.
Did you ever see where neodymium comes from?

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Re: My Electric Motorbike

Post by Dui, ni shuo de dui » Nov 23, 2017 5:22 am

John in CR wrote:
Nov 22, 2017 12:12 am
High performance and lead simply don't belong in the same sentence. Regarding some low power craptastic lithium scooter pack, I wouldn't waste my time. I use automotive grade cells to build my packs, so I get safety, high power, long life, and low price all in one package. In the long run the lithium I use is more economical than the cheap lead anchors you want, so there's no upside to those toxic lead batteries that a polluting China so badly now.
Well, yes, you can build some high performance stuff with lead acid batteries. A friend of mine has an electric scooter capable of accelerating from 0 to 100km/h in less than 4 seconds, using 120V SLA. That's quite a nice performance from my point of view, especially considering the fact that it cost him less than 700 USD including the scooter itself (so about 400USd in parts-motor, controller, battery, DC/DC converter and a few other stuff), but of course there's always better.
You could do that with lithium too, but it would cost more than 4-5 times the price.
I never said that was the best solution, but it works nicely. And here in China, SLA batteries are just dirt cheap. 120V 20Ah is about 100-150 bucks. They generally last about a year, but you can resell them since they are recycled, which cuts down the price by about 20% when buying a new set. Sure, it might cheaper to buy lithium in the long run (as long as it doesn't crap on you), but not everyone has the cash flow to support that kind of one shot expense.

I do understand that it is easy to find good raw materials in the US. Please understand that it is not necessarily the same in all the countries around the world, and that we have to deal with what we get :)
Here in China, finding decent lithium cells is actually quite a challenge. And you just can't buy used batteries from the junkyard, I tried once already.

Anyway, I've already said that I plan to go for lithium, so I don't really know why we have this conversation. What I'm looking for is advice on how to build a nice BMS for a LiFe Po4 battery, so if you have suggestions for that, feel free to enlighten me :)

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