Leaf / leafmotor / leafbike high efficiency 1500w motor

[teklektik]

I disagree with Teklektik's assessment of my situation.

I did not mean to simplify your situation or to offend. The post was specifically about Leaf business practices and I mentioned you incidentally as an example of an atypical Leaf customer. The specifics of your situation were not the point at all.

Give me a break here - I'm very sure that their customers also ask about hill-climbing, etc - not just speed. I view it as having an in-house Dogman Dan functionality. We see folks here all the time asking for motor advice. Same deal. Those folks are non-technical and want to be told what to buy based on their various requirements. I wasn't going make a laundry list of possible terrain and performance requirements for that post so I used the simple 'speed' example for brevity not because that's your only concern.

My (apparently poorly expressed) point was that you have some requirement(s) in mind and went through a lot of research and learning to to make a more 'enlightened ES-type' decision by going after after wind information, etc to make a selection. Their average end-user doesn't bother to learn all that stuff - but in the end you both need to order the same way - which sucks for you.

This seems like a good company and folks here have been happy with the service. Stop arming yourself for a battle and just order the damn thing. You will be happy.

 

[teklektik]

For those interested:


The email 6T value is peculiarly high - interestingly corresponds to the model with the poorest fill.
Kv calculated using 48.24V test voltage from dyno data.

Hey Nep-

• So it looks like we have a pretty solid resolution to the data question - your seemingly aberrant point corresponds to the emailed value above and that value is pretty self-consistent with derived values and other email values. This is good!
  
  The issue with fluxshifter's value and the dyno data being off by 5% is not terribly troubling, but odd. Also the wonky 6T value above is peculiar. I have a meet with Justin next week -- maybe he can shed some light on these matters.
  
  In any case - the question of what values to use for ordering is resolved - due in part to Sprocket's persistence.

 

[FluxShifter]

This motor is a 1500w continuous motor in stock form from what I have observed. My 5t on 18s will go 30-40 mph will using between 1200w-1800w will cruising. I weigh 220 lbs. When it gets up to tempeture it will stay between 100oC and 110oC (212oF/230oF) at these speeds and power levels. At a little over 2000w the temp starts to climb which tells me some the extra watts are turning into heat. Sure more watts will push you past 40 mph but doing this will get you high temps the harder you push. I will try venting the covers and see if I can hold 40 mph on level ground and have a steady temp. It is fun cruising next to cars and pedaling past them for like 10 minutes though 8)

Leaf bike tucks their temp sensor under the coils between the halls. It grounds through the halls and is the 6th wire in the hall connector. My temp signal wire is purple.

What is the safe temp for hub motor components?

Averaging 45 wh/mi is that because I'm a heavy bloke?

 

[neptronix]

Keep in mind that you are testing your motor during summer. Any motor will suffer during summer quite a lot. I took many 30 mile long rides at 45mph ( ~2500w continuous )when it was 60f out - no problem. It's averaging in the 90's here and my leaf motor gets hot within 5 miles of 2500W cont. though.
We're in motor melting season in NOrth America.

I believe that motors are tested at 70F, so that's a fair temperature to come to a conclusion at.

I think it is still strange that you are seeing that much heat. Are you sure that your temp sensor is calibrated right? at 100C, the motor will be so hot that you cannot touch the case for longer than a second.

When going this fast, it's useful to tuck and pedal. I am 185lbs and 6ft. tall myself. I always tuck above 35mph. It makes a few hundred watts difference in power consumption.

 

[teklektik]

flux-
What temp sensor did they install?

 

[SprocketLocket]

Teklektik, I realized some time after I hit Submit, that I should have phrased that line, "I respectfully disagree...". I've updated that post likewise. I get what you were saying now. I love your posts, you're so effing smart, and (perhaps even more importantly) I know, like Neptronix, you only want things to go in a positive direction. And hey now, you get a little defensive too sometimes, c'mon! So I'm definitely gonna give u a break! Although with the data now, I definitely didn't need the kick in the ass to order it, LOL! Woohoo! I'm there!!! Yes, my feelings about everything have turned up a lot. The 7Turn appears it will be EVERY bit as fast as I need OR want it to be--and then some. Yes!! I like that new graph too .

I just didn't want LB making the decision to round-up, or round-down, if I threw a random RPM at them. I would rather make that decision.

When this is finally over, I plan to make a build thread, and put it in my sig like nep, with a 'recipe' for a strong fatbike build, and hopefully it will prevent the ridiculously long journey this has been (almost entirely for other reasons). In fact, this LB thing has been one of the easier tranches.


Hey - did anyone notice that FluxShifter's no-load was exactly in the middle of the nominal range given for the 6T (485)? Here's what I think happened. He asked for 5T and 500rpm. 500 is almost exactly between their data points of 486 for 6T, and 520 for 5T... slightly closer to the 6T. He was basing this on the estimated 504rpm at the time for tT. So, to me it looks like they erred towards what was mathematically closest to his 500RPM request over the winding request, which, they did previously indicate they would do. (I would wonder how to account for that otherwise.) The fact remains that he loves the motor, and it performs excellent for him. My noobness also is wondering if, somehow, a wind slower than 4T (5T or 6T) is actually gonna help people hit higher speeds (at least w/the right voltage), due to more torque when the wind resistance gets high.


QUESTION: anyone have any ideas how accurate that temp sensor would be wired into) a food/barbeque temperature sensor (those digital skewer-type things, available cheaply from China on Ebay? (Yes, I know CA3 has temp sensing; but asking for those who don't want or won't get one.) Many of those gizmos could fit nicely on a handlebar. I don't know if there's a standard/common voltage range thermisters use, but since CA3 expects a certain range, maybe there is.

 

[teklektik]

Hey - did anyone notice that FluxShifter's no-load was exactly in the middle of the nominal range given for the 6T (485)?

Dude - really good observation! That does look like a strong possibility and it makes all but the dyno data line up. This is good.


Anyhow - I'm glad some of the posts seem useful for you.
I also do understand your concerns about ordering. My first two motors were shipped from Texas not China - after an astounding seven week wait - with wrong color motors, wrong spokes, wrong rims, out of true, damaged wires. Got my money back from Capital One really quick but the time was gone forever.

 

[Kodin]

That's really weird; everything I ordered from Leafbike had great customer service, excellent responsive communication, (OK, once or twice I had to wait over 24 hours for a response,) and parts arrived 2 weeks after I placed the order.

Regarding accuracy of the temp sensor, at room temperature, it seems to deviate from my other temperature sensors by between 0.1 and 0.3 degrees C according to my Fluke meter.

(My highly technical testing setup)

And a closeup of the screen:

 

[neptronix]

Hmm, good to know.
My setup is pretty ghetto. It's a turnigy IR temp sensor that i point at the coils through the vent holes..

Shameful, no? :lol:

 

[FluxShifter]

The NTC thermistor is a 10k ohm. I checked the resistance at both sides of the hall connector and at the CA thermistor pad. All were the same. Did a voltage drop test on the ground side of the hall connector to the CA and the drop was 10mV witch is in spec for a computer circuit. Since there is little resistance in the temp sensor circuit I believe my readings are accurate. Unless my CA is not calibrated correctly but it is brand new. After letting the motor cool over night the temp of the coils was 20.1oC/68.1oF. The shell of the motor as measured from a modified BBQ thermometer was also 20.1oC/68.1oF. I rode up and down my street till I saw 150oC/302oF on my CA. After 10 minutes the temp on the CA had dropped to 99.8oC/211.6oF. This is about the same time as the outer shell temp stopped rising at 61.4oC/142.5oF. The shell was hot to the touch and I couldn't hold my hand on it long. I will have to vent the covers and place my BBQ temp sensor next to the coil temp sensor and see the difference. The coils are the hottest part of the motor so at what temp do the halls become damaged? How hot do the coils have to be for how long to demagnetize the motor? Will the solder melt before anything else is damaged?

I tried modifying a Taylor BBQ temp probe to work with this coil temp sensor but it didn't work. The coil temp sensor is a 10k ohm and the BBQ one was a 100k ohm. Now I have a BBQ temp gauge with a couple feet of probe so I could use it monitor the temp of a controller or battery.

The no load rpms I calculated off the mph on my display. At a low SOC I saw 37.5 mph or 485 rpm on my 26" wheel. At a high SOC I saw 41 mph or 530 rpm. The average of these is 508 rpm so I do believe I got the correct 13*5t 500 rpm wind. On 13s it will pull me up a steep hill at about 24 mph. On 18s it will pull me up the same hill at close to 40 mph. This motor does what I wanted it to do. Has a good balance of speed and torque. If I had a 29" wheel I would probably go for the 10*6t 400 rpm wind.

 

[neptronix]

Sounds like the temp sensor is accurate then. Thanks for the post.
You're a mountain man like me. Very little of my riding is on flat ground. What kind of hills are you facing? I can't imagine that you are building that sort of heat up on the flats.

I have measured up to 200C at the coils ( holy crap! ) without visible or functional damage to the motor yet, amazingly enough. But >100C is where magnets usually tend to suffer. I will open up my motor today and post a picture of the damage if any to the winding varnish.

 

[teklektik]

Unless my CA is not calibrated correctly but it is brand new.

Nothing to calibrate in the CA - it's all in the quality of the thermistor and the associated NTC 10K beta specification that determines the error at higher temperatures.

You are getting good results at room temp which is pretty much beta-independent. The '10K' spec is actually the expected resistance at 25C so all '10K' parts should be pretty accurate at that end of the temp range based on the quality of the part - it's the high temp accuracy which develops based on the beta that really requires the test because that relies not only on the quality of the part but the match of the beta specification to that which the CA expects - a different matter.

• You will need to compare the temps at around 100C to check the appropriateness of the beta value (i.e. if the thermistor was a good choice). The CA expects a 10K NTC thermistor with a beta of 3900 but anything in the 3800-4000 range is fine. The beta is sort of the slope of the temp/resistance curve so an improper beta throws off the higher readings because the CA will interpret the resistance as the wrong temperature. That said, even a part slightly outside the recommended range won't make more than a few percent difference.

FWIW: The new CA p10 release has a more readily visible temp alert that I think you may find helpful so you don't need to wait for the display to sequence to the temp value - should be released shortly.

Here's a post addressing your temperature questions (info by Justin)...

• EDIT - added more NTC explanation above....

 

[FluxShifter]

I do have lots of hills to contended with much like your terrain Nep. To get the temp to 150oC I had to ride up and down my street a dozen times using a lot of regen at the bottom. Not sure of the grade in front of my house but pedaling up it is a chore. I will set the CA for a max of 130oC just to be safe. I hope venting the side covers helps.

 

[mchlpeel]

So we have actual hard figures to go by

Nep has the 4T and recorded 631RPM at 48v

Flux shifter has the 5T and has recorded 508RPM at 48v

We have email confirmation that the 6T is 485RPM at 48v

The 6T figure does not look right at all when you consider the 7T is said to be 380Rpm (email figure)

It doesn't appear to be an even spread. What's going on?

 

[neptronix]

That's fairly steep.
I do all my grade calculations using toporoute.com. Very handy tool that uses google's elevation data.

I live next to a lot of 3%, 7%, and 10%.. the only flat land is 3 miles away.

It's time to vent that bad boy for sure.

 

[SprocketLocket]

How would an 8T be expressed? (8*8T?)
What is the first number -- pole count?

What is the easiest way for people to know what kind of motor they have, if they get the cover off: count the poles? (From what I have read here, counting the turns is not possible without damaging the motor?)

What does "SOC" stand for? I searched it. Many people were using the term, every time acronymized. Couldn't figure it out by context.


7T with the new numbers is still pretty fast for 29'er offroaders (48V):
32.7 mph no-load
26 mph loaded/80%/real-life estimate max
31 mph in 120% mode, estimate
Most efficient cruising speeds (if I calculated correctly): 21-23mph, which is beyond my fear point.

Fluxshifter, thanks a bunch for trying that thermister in your barbecue themometer and explanation! I think it may have been you that I originally got the idea from! I still like your idea of using one to monitor other temperatures.

 

[mchlpeel]

Hey guys sorry to throw a spanner in the works. After all this discussion I decided to ask Leafbike what the unloaded rpm was for each winding at 48v.

Here is the response.

16x4T　（６８０）

13x5T　（５８０）

10x6T　（４８０）

9x7T　（３８０）

 

[neptronix]

:lol: :lol: :lol:
They keep giving out different numbers.
These numbers conflict with their dyno graph.
These numbers conflict with their webpage listings.

So, who do you trust? people who received motors and measured the RPM at nominal voltage ( the proper way to do it ), or the Chinese vendor wheel of fortune?

Yes... i am so convinced that these motors step down an equal 100rpm per turn :lol: sorry guys, i've been lying to you this whole time. :lol:

 

[mchlpeel]

We have decided that the above is accurate.

Why are the 5T and 6T such close rpm figures compared to the 4T and 7T
It doesn't look right.


It's just ridiculous that they are messing up something that should be a simple request
How can there be so many variations of projected rpm.

 

[neptronix]

Voltage determines rpm.
My guess is that leafmotor is measuring at various voltages every time they send an email, or simply makin' stuff up.

Since our measurements were adjusted to 48v properly, you can assume our 48v tests are correct +/-5% ( accounting for voltage sag under ~2A of load )

 

[mchlpeel]

My biggest issue is that I was thinking about buying the 5T for the extra torque however, if the 6T is in fact 485rpm at 48 v it will be good for 30-35mph at 14s.

Problem is if the numbers are not accurate then the 6T would be a lot slower and I will wish I had bought the 5T

 

[cycborg]

I was thinking about buying the 5T for the extra torque

Every once in a while it's good to point out that a higher turn count doesn't result in more torque unless your controller limits phase current. For a controller that limits battery current only, the low-speed torque will be essentially the same between windings.

The advantage of a high turn count motor is somewhat more subtle. For the same torque and RPM, the higher turn count will result in lower phase amps, which eases the demands on the controller and allows for smaller phase wires (or lower conduction losses in the same phase wires).

To demonstrate this to yourself, go to the Grin simulator and do a side-by-side comparison of two systems that are identical except for turn count on the motor. The torque of the high turn count motor will be slightly higher due to controller and conduction losses and possibly copper fill, but probably not as much as you expect.

For more in-depth understanding, immerse yourself in the legendary Science, Physics, Math, & Myth thread.

 

[mchlpeel]

Ok I understand that.

Let's look at another way
I have a 50.4v nominal battery I want to have a top speed of 35 mph. Which winding do I buy?

The 5T or the 6T???

 

[cycborg]

I have a 50.4v nominal battery I want to have a top speed of 35 mph. Which winding do I buy?

The 5T or the 6T???

The 5T will give you a higher top speed, and better performance in general due to higher strand count. Between the 5T and 6T, I'd say this makes the 5T a no-brainer.

However, neptronix's ride testing and teklektik's simulation both show a top speed of about 38 mph for the 4T at 48 V (see this post). Doing a first-order conversion, the 5T would be 4/5 of this, or about 30 mph.

Since you have a high-speed application, the 4T seems like the best choice - one fewer winding strand won't make much performance difference, and you'll be less limited at the top end. Is there a particular reason you're avoiding this winding?

 

[mchlpeel]

well I think the 5T has more copper fill which can only be a good thing.

I was only considering dropping to a 6T because I was under the impression that torque would be increased.