Mid drive vs Hub Motor for 10000 watt project

[johnnyz]

Hey there

I bought a Emmo Zone last summer. It is a great bike. Handles really well and has all the bells and whistles. I immediately pulled the lead acid slugs and put my100 volt Lithium pack in there Along with my Crystalite 18 fet controller set to 70 amps. Pulled the stock cluster and put a CA in it's place. Problem is that while the acceleration is good but top speed is only 55 KPH which is really dissapointing. Motor is a 28 pole motor so has decent torque and average pull is about 5500 watts.

Question:..I want more from this..so, Mid drive with maybe an Astro 3220 with small to very large sprocket on wheel or heavily modified Hub motor??...Any ideas??..

Sabvoton 120 controller sounds good to start...and a 24s 16p pack from Panasonic pf cells..

I was getting average of 32 kw/Km at 50 kph so range wasnt the best either...


Thanks

John

 

[x.l.r.8]

wondering how you are going to try and license and insure this once its done, mrcrash had the same problems. if 55kph is dissapointing on an bike designated to go 32kph then bite the bullet and get a motorbike, even a reasonable sized motorbike will do what you want, or build an electric motorcycle that you can register and license.

 

[johnnyz]

Thanks but not exactly the reply I wanted. I really dont want to debate the merit of the silly ebike laws in Ontario, as the speeds are a joke and in fact make for a more dangerous ride, especially given that they are driven in traffic with cars going double the speed, besides EVERYONE is doing this for this very reason. In the event that through modifications that the bike is capable of 100 kph and at least 75 kms of distance then I would license it.

Back to my question: anyone have any ideas on mid drive motor's capable of 10000 watts or more?...would re-winding this motor get me the results I need?


Thanks

John

 

[flippy]

top speed is dictated by voltage, nothing else. you already have the wattage you need for more speed.
you need to modify the existing pack or replace it with a higher voltage.
replacing the motor for one with a higher kv should be a last resort as motors like this are REALLY expensive.
i would not recommend rewinding a motor with zero experience.

might want to upgrade the controller to a 96v model.

 

[Punx0r]

How much more speed would you like?

A motor controller with flux weakening might get you there and let you keep your battery and motor as-is.

Alternatively, is this motor likely to be already configured in delta? If not, reconfiguring from star/wye would give a good increase in speed for the same voltage.

 

[x.l.r.8]

Something sounds wrong, Is the CA verifing your voltage/Amps because I would expect the increase in voltage to be pushing closer to 60km/hr. Its a super heavy bike but so are a lot of DUI scooters and they are going 60km/hr for 50km with pretty much an upgraded controller and good battery reserves all around the 72v mark. I reduced my voltage to 65v and still see 45km/hr for 40km using hoverboard batteries. Sinking 7Kw into a hub should produce much better results.

 

[johnnyz]

top speed is dictated by voltage, nothing else. you already have the wattage you need for more speed.
you need to modify the existing pack or replace it with a higher voltage.
replacing the motor for one with a higher kv should be a last resort as motors like this are REALLY expensive.
i would not recommend rewinding a motor with zero experience.

might want to upgrade the controller to a 96v model.

Hi and thanks for the response. Yeah the bike currently weighs 240 pounds with my lithium pack (24s 8p). I wouldnt be doing the re-winding, I would take it to one of our people here and have them do it. Being that it is a 28 pole motor I am assuming has something to do with why it is so speed limited, but something doesnt make sense as the 72 volt Lead acid versions will do 50 kph, so I thought the increase in voltage would be more than what I am getting. An ebike dealer here thinks there is probably a board or something preventing more speed in the motor??..never heard of that one before!.

John

 

[johnnyz]

How much more speed would you like?

A motor controller with flux weakening might get you there and let you keep your battery and motor as-is.

Alternatively, is this motor likely to be already configured in delta? If not, reconfiguring from star/wye would give a good increase in speed for the same voltage.

Thanks for the response...the controller I am using is a Crystalyte 18 fet programmed for 80 amps but it never goes about 70 amps.

Dont know what you mean by reconfiguring from star/wye...can a local electric motor buisness perform this modification?

John

 

[johnnyz]

Something sounds wrong, Is the CA verifing your voltage/Amps because I would expect the increase in voltage to be pushing closer to 60km/hr. Its a super heavy bike but so are a lot of DUI scooters and they are going 60km/hr for 50km with pretty much an upgraded controller and good battery reserves all around the 72v mark. I reduced my voltage to 65v and still see 45km/hr for 40km using hoverboard batteries. Sinking 7Kw into a hub should produce much better results.

Yes the CA is telling me what the voltage and amps are. Bike is 240 pounds, and 400 pounds with me on it. The controller is a crystalyte 18 fet set for 80 amps but the most I have seen it pull was 70 and mostly 65. The battery is a 24s8p that is getting tired as I am over the max amp draw for this battery (Made it with the Panasonic NCR18650B cells which are only rated for 5.8 amps each. Resistance as measured by the CA is about .165 ohms. Max range at 50 kph was about 38 kms

I will be making another pack this spring consisting of the Panasonic PF cells in a 24s16p configuration. I think this should get me at least 75 kms at speed. I was thinking of upgrading to a Sabvoton 120 amp controller..


John

 

[SlowCo]

On their website Emmo describes the hub motor as a "GTS Super Torque Motor" so it will probably be a very low kV winding. You'll need more Volts or a controller with field weakening to increase the speed.

 

[HighHopes]

every major city with 100K population will have at least one motor re-wind shop. check the yellow pages (oops.. just dated myself). they can re-wind your motor for you if you don't know how to do it yourself. for the same motor, what you'll get is the same power.. increase the voltage (motor speed) and current (torque) goes down. or vice-versa. if you're upset that the torque goes down to get the higher speed you want you have two options
a) if you are almost at the higher speed you want, say within 20%, then keep everything the same but change the controller to one that can manage field weakening
b) if you're far away from the speed you want then upsize the motor to get higher power. you might also need to re-wind it to get the voltage (speed) you want and of course current (torque) goes down .. but you started at a higher power level with this new upsized motor so when the current goes down could be its not so low anymore as to give a sad ride.

also, to be honest, if you want a high power controller 10kW or more try to stay away from the multi parallel mosfet commercial controllers. 100% of these are total garbage (not something you want to discover while at 100km/hr). that means kelly, sevcon... all those. open them up and you can see immediately the problems if you have an eye for it. yes its possible to design a decent or maybe even good multi parallel mosfet controller, but to date i haven't seen one commercially available.

good luck with your project!

ps. i'm in ontario too... i feel your pain

 

[johnnyz]

Wow...well thanks for the replies...so I did some research and apparently the Sabvoton (http://www.blog.electricrt.com/sabvoton-96v-sinewave-controller-tech-info/) 96 volt controller does have the option for Flux weakening. I also saw a youtube video demonstrating a generic 48 volt system and top speed (unladened) was 65 kph but with Flux weakening the motor's speed was doubled.

I would be happy with 20 kph faster speed. With this controller and initiating the flux weakening is there a possibility of hurting the motor's magnets?..Also, apparently efficiency goes down?

So if I had a machine shop re-wire the motor for 20 kph higher speed and introduced 20-30 amps more than I am pulling now, then torque should be the same and with the additional higher speed due to the re-winding, and if needed flux weakening via the controller?

 

[SlowCo]

I would go with field weakening. Then you don't need to have your motor rewind and can keep the current controller as spare/back up. As the efficiency will go down the temperature of the hub motor will rise at top speed. So it is best to read up on cooling and statorade/ferrofluid:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=48753

https://endless-sphere.com/forums/viewtopic.php?f=31&t=73818&p=1113759

 

[flippy]

Point to consider: flux weakening kills efficiency.

 

[johnnyz]

Point to consider: flux weakening kills efficiency.

Thanks for the reply..but "kills efficiency " isnt very helpful..on the Sabvoton controller, it has Flux weakening up to 150 A...but doesnt recommend beyond 50 A as it says it can de-stabilize the magnets..so if I were to say program the controller for 20 A and I get 20 KPH more speed what is the efficiency loss?..does it directly correlate to the amount in percentage of speed gained, or is there a formula??

John

 

[icherouveim]

Hello,

There is something else you should consider. My first battery pack I had 3 years ago it was made by 18650B panasonic cells. They were very weak, the battery pack was sagging alot. Just to give you an example when the battery pack was fully charged each cell was sagging at 3.3V!! while I was drawing only 4amps per cell and you draw almost 9! This battery pack is going to die very soon.

So firstly you need a new stronger battery pack and if you still have the same low top speed then you can change controller and or modify-replace your motor.

 

[e-beach]

Before you attempt to get your motor rewound, check this out and then check it out again until it makes sense to you.


http://www.ebikes.ca/learn/hub-motors.html

 

[Lebowski]

I would swap the controller for one with fieldweakening.

How much field weakening current you need to set for a certain speed increase depends on the motor, so if you dont know the motor parameters its hard to predict. Extra losses from field weakening are I^2 R... with I the field weakening current.

Arlo1 with his car gets about 80% more speed with field weakening...

 

[x.l.r.8]

I’m with the controller to. Your battery is 3 times better than mine and I get easily equal your performance. The motor will do 75 km/h with 72v so any of the proven controllers (Kelly, power velocity, sabvoton) would probably do what you want. All should plug up to your CA. I wouldn’t go charging the motor yet as it easily does what your after.

 

[johnnyz]

I’m with the controller to. Your battery is 3 times better than mine and I get easily equal your performance. The motor will do 75 km/h with 72v so any of the proven controllers (Kelly, power velocity, sabvoton) would probably do what you want. All should plug up to your CA. I wouldn’t go charging the motor yet as it easily does what your after.

Its funny ..I forgot that a guy called me and bought the same bike and asked me tomake a pack. I made a 20s 8p pack from Panasonic PF cells and when it was done,had 20% less resistance than my 24s pack and when we went for a ride together, even though I had better accelleration, the difference in top speed was only 5 kph!!...and that is with his stock controller and my crystalyte 18 fet beast.

When you mention these other controllers you must mean that they are all capable of field weakening in comparison to mine yes?

John

 

[johnnyz]

Before you attempt to get your motor rewound, check this out and then check it out again until it makes sense to you.


http://www.ebikes.ca/learn/hub-motors.html

Thanks for the post...yeah so the article explains why the motor stops accellerating once the back emf eddies build up...so the sabvoton controller counters that which enables more speed...I am thinking that it wouldnt take much to increase speed 20-25 kph...

Since I am coming into some money I would like to at least have a machine shop look at the motor and perhaps they can improve it...decrease the pole count from 28 to maybe 22 and add more copper if possible...stuff like that and then add a Sabvoton controller...

 

[johnnyz]

Hello,

There is something else you should consider. My first battery pack I had 3 years ago it was made by 18650B panasonic cells. They were very weak, the battery pack was sagging alot. Just to give you an example when the battery pack was fully charged each cell was sagging at 3.3V!! while I was drawing only 4amps per cell and you draw almost 9! This battery pack is going to die very soon.

So firstly you need a new stronger battery pack and if you still have the same low top speed then you can change controller and or modify-replace your motor.

Yeah I know I am way over the amperage the cells can take but remember I am only drawing 65 amps for a couple of secs then it tapers off...it sags to about 83 volts from 99 volts from a stand still..and to about 87 volts when I am crusing at 30 kph and then apply full throttle...BUT consider this; Just for heck I detached one cell (after 330 cycles) and did a capacity test...that cell had only lost about 6 percent capacity!!...couldnt believe it so did one more and it was the same...almost never take the pack down to empty..ususally charge it back up at about 87 volts..

 

[flippy]

capacity is not a metric for how godo a cell still is. you also need to check the internal resistance.

 

[johnnyz]

capacity is not a metric for how godo a cell still is. you also need to check the internal resistance.

I understand that, but they are 2 sides of the same coin...at 1 amp those cells came in at 3000 mah..and after 300 cycles at the same amperage discharge, they are around 2850 mah...resistance can be calculated and involves a known resistance and sag under that resistance..well we know the resistance and the capacity, and the sag is about the same (the whole pack through the cycle analyst which calculates this based on voltage/load and voltage sag), so considering I have not been kind to them, this is an excellent result. Doesnt matter to me as I am going to make another pack 24s 16p from Panasonic PF cells as they are the best bang for the buck, and this pack should be able to handle 80-100 amps peak very comfortably.


John

 

[johnnyz]

Well....this HUMONGOUS controller (Yuyang King Controller ) with Blue tooth is the rage here..with some bikes I have seen personally go past 85 kph...so...its all hooked up but of course the halls and phase wires will need to be tried..perhaps all 48 combinations...



This does have field weakening...or so I think it does..we will see what the wheel spins at in comparison. If only I can figure how to connect the CA... Will post back


John