"Edge" DD hubmotor, 1500W, 35mm, Al core

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spinningmagnets
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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by spinningmagnets » Mar 16, 2018 12:42 am

35mm wide stator in a DD hub laced to a 20-inch rim is an awesome set-up. If there are no build restrictions and the budget allows for all options, this is definitely one of the top options. All the benefits of DD hubs, but also a good hill-climber.

What turn-count/kV of motor did you select, and what top speed did you achieve with 20S?

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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by Green Werks » Mar 16, 2018 4:37 am

The motor is a 4t as far as top speed I don't know
it is in a KMX trike and it is a little squirrely
but it went from 0 to 30 mph very quick
and then I let up but it still had throttle left
It will fly up hills

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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by teslanv » Mar 16, 2018 7:49 pm

The 4T winding is about 11 RPM per volt, so at 72V Nominal, you are pushing upwards of 800 RPM. In a 20" Wheel, that would be close to 50 MPH top speed.
Great Motor in a small wheel, paired with a great controller and the respectable Samsung 30Q cells. It's a hard combo to beat.
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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by Green Werks » Mar 18, 2018 4:51 am

Question for the all knowing and powerful Spinning Magnets
I was going back reading your post and picked up on this statement you said.
( If the Edge 35mm wide stator gets hot on your hills running your watts, go to more watts, or upgrade to more copper mass by swapping to the MXUS 45mm wide stator motors)
I understand the wider stator but I was wondering about the going to more watts thing
can you enlighten me.
did you know that on go daddy the name spinning magnets .com is selling for $3450.00
you be the man dude
thankx

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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by spinningmagnets » Mar 18, 2018 5:13 am

Imagine you are on an uphill and at Wide Open Throttle / WOT. The controller is applying more amps in order to get the RPMs up to the motors top speed, but...under the current load it is unable to accelerate and is stuck in a "bogged down" situation.

Sometimes adding more watts can allow you to accelerate up to the higher RPMs, where the motor runs more efficiently. Then, the controller will send fewer amps to maintain the speed.

After achieving top speed, it can be possible that the load is heavy enough that even running at a higher and more efficient RPM still requires a level of amps to maintain its speed which exceeds the motors ability to shed heat, so the temps still rise.

In that condition, more amps without the copper mass to accept it will only cause additional heat (existing copper mass is already saturated). The next step is a larger motor, even without changing the input watts yet.

Also, one option to improve heat issues without changing the top speed is to go to higher volts, and swap the hubmotor to a smaller diameter rim. You can even just swap to a smaller rim first to see if that helps enough with the heat, in spite of the lower top speed.

"Spinningmagnets.com"?... yeah, I checked a while Back when it was $2500-ish. I don't want a website that bad.

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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by Green Werks » Mar 18, 2018 7:10 am

spinningmagnets wrote:
Mar 18, 2018 5:13 am
Imagine you are on an uphill and at Wide Open Throttle / WOT. The controller is applying more amps in order to get the RPMs up to the motors top speed, but...under the current load it is unable to accelerate and is stuck in a "bogged down" situation.

Sometimes adding more watts can allow you to accelerate up to the higher RPMs, where the motor runs more efficiently. Then, the controller will send fewer amps to maintain the speed.

After achieving top speed, it can be possible that the load is heavy enough that even running at a higher and more efficient RPM still requires a level of amps to maintain its speed which exceeds the motors ability to shed heat, so the temps still rise.

In that condition, more amps without the copper mass to accept it will only cause additional heat. The next step is a larger motor, even without changing the watts.

Also, one option to improve heat issues without changing the top speed is to go to higher volts, and swap the hubmotor to a smaller diameter rim. You can even just swap to a smaller rim first to see if that helps enough with the heat, in spite of the lower top speed.

"Spinningmagnets.com"?... yeah, I checked a while Back when it was $2500-ish. I don't want a website that bad.
Thank you for your time and feed back
This might explain why I was seeing what I was seeing on the CA
This is how it went down
with the 52v ga battery set up for 70 amps and 4000 watts the temp would rise pretty quick
But when I put the new 72v 30Q battery in set up for 70 amps and 6000w the little 205 V2 35mm suddenly became (a hole lota mo aggressive) to my great delight.
well usually there is no free lunch so I started monitoring temps but to my surprise it was running cooler
to the point that I was thinking that man the CA is whacking out. You can imagine what happens when you get a new part, you immediately start abusing it so it will fail while still under warranty ( it's ok WCEC I'm joking kinda)
Well I was hitting it hard repeatedly, and It would hang in their so may be that is what's going on
adding more watts made it run cooler thankx so much for your help
The other thing that I wanted to ad was for all the fatties like me out their
A 100lb. KMX trike with me at 250 lb. with the 72v 30ah Q battery and the 205 V2 35mm (AKA edge ) set to 70 amps 6000w
Dude will totally hall ass to the point where if I cant get a handle on it I will have to build a new frame just out of the necessity
for stability and safety.
Cheers.

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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by spinningmagnets » Mar 18, 2018 8:01 am

I started monitoring temps but to my surprise it was running cooler
I'm glad to hear that. It sounds like with the steepness of your particular hills, combined with your particular bike + body weight...you have found a balance of components that work. You might consider adding Ferro-Fluid, which would provide a safety margin in heat-shedding (plus hub-sink fins?). Another option is to did-assemble the motor (maybe next winter?) and coat the stator with water-proof motor epoxy/enamel, then cut ventilation holes in the sideplates. I mention the FF first because...once you cut the sideplate holes, it would be a pain to seal them up and go back to the previous state.

(A coffee-cups' worth of ATF works well, but unlike FF, ATF will always finds a way to leak out)

That's also why I mention swapping-in a smaller diameter rim first. It may seem to be a pain and time-consuming, but once I committed to a rim-swap, it didn't really take that long, maybe $150 for rim and spokes?. It was certainly easier and faster (and less expensive) than getting a higher-voltage battery pack ($700-ish?), and possibly requiring a new controller (18-FET, $150-ish?).

For the street (with no potholes) there are many benefits to a smaller rim, and you can always raise the voltage later if the rim-swap doesn't quite work out as well as you hoped...

If my house burned down, I'd take the insurance check, and...to replace my stretch cruiser, I'd get a longtail cargobike with a 20-inch rear wheel (ODK-II, Edgerunner, etc...), and load a 16-inch moped rim (same diameter as 20-inch bicycle rim) onto a 35mm Edge (hidden behind cargobags). Where I live, the hills are short and mild, so...I'd only need 48V. A mid drive or high volts would be a waste in my location. However, If I moved to a hilly area? I'd go to 52V, 60V, or 72V as needed.

If I moved to ultra-hills like San Francisco, I'd use a mid-mount motor, like a single-speed Lightning Rods big block. Mid drives (through the gears) seem to work best at 2500W and below, and I'd have to stock up on having a spare chain with new sprockets (replace as a set when worn)...

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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by John in CR » Mar 18, 2018 6:55 pm

Hill climbing is accomplished with torque, and current creates torque. The problem is that heat goes up by the square of current. Only in the case where you've severely limited current below a motor's capacity with that load will adding more current (higher watts) help you tackle an incline that's already causing heat problems. Adding voltage isn't going to help unless the hill is so short that a faster running start with the higher voltage will help you get to the top in a time short enough time that heat hasn't built up enough to be a problem.

People throw this idea of getting up to an efficient range of operation like it's some kind of cure all. When it comes to real hills, getting up to a higher rpm where power production is more efficient doesn't really help from a heat standpoint unless the hill is short enough that making roughly the same heat for a shorter time saves the motor. I climb the same long hills on a daily basis at different speeds based on traffic, and speed has very little effect on motor temp. Faster (ie running at higher efficiency) makes it hotter due to the extra power to overcome wind resistance despite the greater efficiency in making that power. Instead of thinking in terms of power and efficiency, it's best to look just at current when it comes to hills.

Don't take my word for it, use the simulator at Ebikes.ca as a learning tool. Use a motor for which thermal modeling is available and plug in a grade. Look at % efficiency and motor temp using different throttle positions. Then change the controller and increase current and do the same. Forget the "efficient rpm range" nonsense when it comes to motor heat. Motor heat comes primarily from current. Efficiency matters when it comes to getting a given mechanical power out of your battery pack for a longer period.

With a given motor there are only 2 options when it comes to real hills:
1. Reduce the gearing, ie smaller wheel for a DD hubbie, always the first and best option, because it increases performance in all respects and if you come up short on top speed, just increase voltage giving you more power to go with your already increased thrust and efficiency. Smaller wheels are another good thing to learn about with the simulator.
2. Improve cooling to shed heat faster, allowing higher current for greater torque without increasing motor temps.

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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by harmonist » Mar 18, 2018 7:35 pm

I'm also running an edge clone from west coast cycles, awesome guy to deal with and really fast shipping.

My top speed so far has been 42mph but it doesn't get there easy, it gets up to and holds 37mph nicely which is about the tops I need anyway so that works out well, its the 4t wind in 26" wheels, I'm only running a 12fet controller so it warms up a bit and the motor was a little warm also but there's a tonne of hills around here. According to cycle analyst I was putting out 56 amps so with a full charge of lipos at around 74.7 thats about 4183 watts, works for me, its taking way longer to set up than my old bbshd but worth it so far.
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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by Green Werks » Mar 19, 2018 4:55 am

harmonist wrote:
Mar 18, 2018 7:35 pm
I'm also running an edge clone from west coast cycles, awesome guy to deal with and really fast shipping.

My top speed so far has been 42mph but it doesn't get there easy, it gets up to and holds 37mph nicely which is about the tops I need anyway so that works out well, its the 4t wind in 26" wheels, I'm only running a 12fet controller so it warms up a bit and the motor was a little warm also but there's a tonne of hills around here. According to cycle analyst I was putting out 56 amps so with a full charge of lipos at around 74.7 thats about 4183 watts, works for me, its taking way longer to set up than my old bbshd but worth it so far.

bike.jpg
That is a sweet set up
On my bike I have a edge also a gary fisher bike with a 52v 24 ah ga cell battery
it alos has a 26 inch wheel
I ran the 12 fet for a while but like you said it would get warm
I switched over to the 18 fet and that cured that
the controller is set up for 70 amps and 4000w
It will hit 43 mph and it is a great hill climber
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Re: "Edge" DD hubmotor, 1500W, 35mm, Al core

Post by Dumsterdave » Apr 12, 2018 6:32 am

Can you get this from a European retailer?

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