Baserunner z9 long throttle delay from stop.(Solved)

[tnoller5972]

With a max of 1500w and no more than 5a of field weakening and you shouldn't have any problems with overheating. Of course it will depend on your use case and overall load on the motor.
You can also reduce the phase current some which will greatly help with reducing heating but will reduce low end torque some. So you could still run field weakening for higher top speed and still run 1500w+ peaks with say 40 to 45a phase current rather than 55a phase current. It will take some playing around to get it where you like it but it's so worth it once you get it there.

 

[powerpeddles]

With a max of 1500w and no more than 5a of field weakening and you shouldn't have any problems with overheating. Of course it will depend on your use case and overall load on the motor.
You can also reduce the phase current some which will greatly help with reducing heating but will reduce low-end torque some. So you could still run field weakening for higher top speed and run 1500w+ peaks with, say, 40 to 45a phase current rather than 55a phase current. It will take some playing around to get it where you like it, but it's worth it once you get it there.

Running the MXUS XF19C and the BR with a 52v battery with a 40a BMS, we see a 2000 watts peak on the CA, but it builds to that number. At wide open throttle, it will peak at 700 watts and then climb to 200

 

[tnoller5972]

Yeah it depends on the ramp rates you have in the CA/BR. The standard pass thru throttle mode controls torque rather than power so that's why it pulls more power for high speed and less for low speed off the line. It's why you can have the throttle set on cruise control at a consistent voltage but the power will increase as speed increases. However the three phase current that you cant see on screen would be high at low speed.

 

[E-HP]

It just depends on what you are looking for. If you are wanting a bike than can really take off and go with higher power and torque levels then yeah I'd say go for it but again then you would be in the same boat of stressing the battery.

I'd focus more on phase amps than battery amps for taking off. If your controller has a higher phase amp limit, even with a modest/lower battery amp rating, it will accelerate harder than a controller that can lower phase amps but higher battery amps; so you don't need to stress the battery if you have the right controller. In this example, the 35A controller beats the pants off the 50A controller all the way to full speed.

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

 

[tnoller5972]

Yeah I agree to an extent. The benefit from higher battery current is a very minimal increase in mid to high range acceleration but not much for a lot of battery juice and heating of the motor. I looked at the graph but used a standard wind instead for the 26in wheel size. At 20mph the high phase low battery accelerates at 2.18 mph/s while the higher battery with lower phase is about 2.32mph/s. So too small to really notice but it would definitely effect overall performance. Just comes down to finding the right ratio for the use case but in the end I agree higher phase with lower battery is usually better all around for a given setup. For my bike it finally came alive once I hooked up dual batteries and could push the battery amps up from 25a max to about to 35 max but I'm suffering in all other areas other than acceleration.(Heating, range,etc

 

[tnoller5972]

Also to be fair you did use fast wind motors in 26in wheels with one at 70/35 phase/battery and the other at 50/50. Of course the higher phase will perform drastically better in that winding motor in that size wheel. However in the real world with these motors anything at or past 60a of phase current on a standard wind in a 27.5in wheel would instantly shred the gears. Even with a easy take off with low watts on screen and it still heats up a good bit from high phase current. Same with plugs. This is what I mean when I say phase for low speed acceleration and battery for mid range acceleration.

I'd focus more on phase amps than battery amps for taking off. If your controller has a higher phase amp limit, even with a modest/lower battery amp rating, it will accelerate harder than a controller that can lower phase amps but higher battery amps; so you don't need to stress the battery if you have the right controller. In this example, the 35A controller beats the pants off the 50A controller all the way to full speed.

Motor Simulator - Tools

Our ebike motor simulator allows you to easily simulate the different performance characteristics of different ebike setups - with a wide selection of hub motors modeled, and the ability to add custom batteries and controllers and set a wide variety of vehicle parameters you'll be able to see...

ebikes.ca

 

[E-HP]

Also to be fair you did use fast wind motors in 26in wheels with one at 70/35 phase/battery and the other at 50/50. Of course the higher phase will perform drastically better in that winding motor in that size wheel. However in the real world with these motors anything at or past 60a of phase current on a standard wind in a 27.5in wheel would instantly shred the gears. Even with an easy take off with low watts on screen and it still heats up a good bit from high phase current. Same with plugs. This is what I mean when I say phase for low speed acceleration and battery for mid range acceleration.

It’s just an example. Any motor will exhibit the same type of impact on the low end torque. Put a GMAC 8T in or whatever motor you want and you have the same impact. Low end torque is limited by phase amps, not battery amps.
Higher battery current will help extend the torque curve to provide more torque in the mid to upper range.

 

[tnoller5972]

Yeah that's exactly what I said lol. You were saying that battery did nothing and that higher phase was better through the whole speed range when it wasn't but was close and only reason it was close was because it was a fast wind in large wheel so large phase amps are needed to run it properly. Like I said before phase for low end and battery for high end.
Using that same test with a standard wind motor in a 27.5in wheel(makes more sense) one with 50/50 and other with 75/25 phase/battery. At 20mph the high phase low battery is only pulling 1.5mph/s meanwhile the 50/50 at 20mph is pulling over 2.3mph/s. The only real benefit to a higher phase is the low end take off but once you get to around 15mph it's more dictated by battery/wattage. So unless you have tons of stop and go and need the bike to shoot off the line I'd say it's pointless. Most spend their time somewhere in the 10 to 25mph zone so the phase current only helps so much when most aren't riding at below 10mph often. In my bike with 55a of phase off the line it's almost too much. I have to let it ramp slowly to help but any more phase and the clutch/gears would be struggling.

 

[E-HP]

Phase and battery amps aren’t independent, but controller dependent. If you want smooth acceleration without the sudden drop off in the torque curve, you need to raise phase amps, but that requires raising battery amps if neither is limited. Ideally the curve is smooth without the sudden drop off, if the motor can handle it.
Phase current is important for acceleration or climbing everywhere in the range. It’s the only input the motor sees, the battery current and the controller are the means for producing phase current. Climbing a steep hill or power wheelies at 25mph take phase current. Just limit battery current what the battery can handle, and phase current as high as the motor can handle.

 

[tnoller5972]

I agree with all of the above. Phase current is always at play even at full speed I was just pointing out that the effects at different speed ranges. Like I said and you said yourself, "Low end torque is limited by phase amps, not battery amps.
Higher battery current will help extend the torque curve to provide more torque in the mid to upper range." I never said battery is for improving low end torque so don't know why we are still going back and forth about this. I was simply stating how your test graph in the simulator was skewed in your favor by having a fast wind in a large wheel which would obviously need large phase currents to drive it. Again though, the battery amps increase shows an appreciable increase to torque and overall performance in the mid to high speed range.

In the end we're both saying the same thing, Just limit battery current what the battery can handle, and phase current as high as the motor can handle.

 

[neptronix]

Found this thread after researching which grin kit to buy. Great info.

I was wondering what you thought the highest speed you'd cruise this motor at continuously? i'm thinking that 25mph with bursts of 30mph could be possible.

 

[tnoller5972]

The speed at which you run it isn't really much of a factor but the load required to hold that speed or accelerate to it is. Motor efficiency generally always goes up as speed goes up. As you near no load speed your power drops due to back EMF from motor voltage being close to battery voltage so even though you are cruising at 30mph it could only be pulling say 800w.

I'm running mine at 1500w regularly with about 9a of field weakening for higher top speed. With this on a full charge I can top out at around 35mph and near dead I can hold 30mph. The heating from using FW is noticeable but not detrimental in my use case but that's from how it works and its negative effect on efficiency, not the higher speed.

So in short don't worry about the speed you are running it at but more so the load required to hold that speed/accelerate. Just don't lug the motor up a hill at slow speed at full throttle and you'll be golden but even then the temp sensor will save you if you have a motor with temp sensor like sx2 but overall,
speed isn't a problem.

 

[E-HP]

Found this thread after researching which grin kit to buy. Great info.

I was wondering what you thought the highest speed you'd cruise this motor at continuously? i'm thinking that 25mph with bursts of 30mph could be possible.

I cruise pretty slowly, but in my opinion, I'd like to shoot for something north of 80Nm available at whatever my cruising speed in order to have effective acceleration to get out of hairy situations. I define effective acceleration, literally, by a seat of the pants test. Ride at cruising speed, close your eyes, and roll on the throttle. You should be able to feel it accelerate if it's useful. If you don't feel it, and open your eyes and see the speedo creeping up slowly, then that's not useful. I'm at around 95Nm at 25 mph and 80Nm at 35 mph, so decent acceleration in that range for city traffic if the need arises.

 

[neptronix]

I'm interested in knowing about what speed it can hold continuously without melting, sans the heat we get from accelerating.
I do very long rides, so heat buildup matters.

I'm curious to see if you could ride at an average speed of 30mph and not have it melt / trip the thermal protection.

My educated guess is:
In this semi-hot rod condition, we have 75w of heat to shed. I think this is within the range of heat a motor like this can disperse.



If we simulate some mild field weakening to get 30mph, we gain 0.1% efficiency but now have 93 watts of heat to shed. This may be over the limit for continuous use.



I'm thinking this motor might handle 30mph all day unless it's hot outside.

 

[neptronix]

I cruise pretty slowly, but in my opinion, I'd like to shoot for something north of 80Nm available at whatever my cruising speed in order to have effective acceleration to get out of hairy situations. I define effective acceleration, literally, by a seat of the pants test. Ride at cruising speed, close your eyes, and roll on the throttle. You should be able to feel it accelerate if it's useful. If you don't feel it, and open your eyes and see the speedo creeping up slowly, then that's not useful. I'm at around 95Nm at 25 mph and 80Nm at 35 mph, so decent acceleration in that range for city traffic if the need arises.

Are you referring to your experiences with SX2 motors or did we get our wires crossed?

For clarity i'm asking about the SX2 motor

 

[tnoller5972]

Are you referring to your experiences with SX2 motors or did we get our wires crossed?

For clarity i'm asking about the SX2 motor

Yes. I've ridden it for over 1k miles as stated above with no problems but for me the thermal rollback does kick in on longer rides from how I have it setup. With no field weakening or a lower amount and a more reasonable say 1200w max and you should be golden to run it for long commutes without problem.

Most of my rides are short and I like to go fast so I can push it hard without worry of it falling on its face mid trip from thermal rollback. However for longer commuting style rides, just use more reasonable values for the motor.

 

[E-HP]

Are you referring to your experiences with SX2 motors or did we get our wires crossed?

For clarity i'm asking about the SX2 motor

My bad. I should have noticed your Grin motor reference. It’s too bad that the simulator doesn’t provide overheating data for all motors, but that’s a lot of modeling (destructive testing?). I do close, looking at various similarly designed motors that do have temp modeling, compare their efficiency, and then extrapolate/guesstimate. Actually works well to get within the ballpark.

 

[tnoller5972]

As far as my knowledge the only motors that have thermal rollback/temp modeling in the motor simulator are motors that they have actually put in the wind tunnel and tested. If you put a certain motor in the test and it says "not modeled" in the lower right where it would normally tell you how long til you'll overheat, it just means they haven't tested it(thermal testing at least). However using a motor that has been modeled that is similar to one you are using works good like you said for ballpark idea of how motor will respond to give setup, ambient temp, load etc...

 

[amberwolf]

I'm interested in knowing about what speed it can hold continuously without melting, sans the heat we get from accelerating.
I do very long rides, so heat buildup matters.

I'm curious to see if you could ride at an average speed of 30mph and not have it melt / trip the thermal protection.

This reply is more for other/future readers, but:

As another already replied with, and I'm pretty sure you already know it will depend on your specific riding conditions.

If you're on flat ground with no wind, then 30mph will take a certain amount of power. If you have headwinds, even slight ones, it could increase your power usage significantly, and create more heat in the motor; if it's already at the edge of some limit, it could push it over that limit. Tailwinds could decrease it; crosswinds are more likely to increase it (sometimes worse than direct headwinds might, depending on the aerodymics of the bike and you and the stuff on it).

I doubt you have much in the way of inclines or hills to deal with there, but if you do, then those will also take more power to go up, and the faster you're going up them and the more total weight there is, the more it will take.

 

[neptronix]

Looked up OP's bike. If i'm right, it's got 27.5" wheels. I run 26" or 24".

Out of my own curiosity, i decided to see if this motor could benefit during acceleration from a 24" wheel, since it has a lack of torque.

Looks like we get a free 10ft-lbs of torque at approximately the 50% efficiency point, and cross pass 50% efficiency a bit sooner.
That's pretty substantial and should have an impact on heating during acceleration.



At 32.5mph cruise ( speed adjusted to be equal ), The 24" wheel is making 8 watts less heat. In this case, we're making about 130w of heat, which is probably too much for this mid sized motor.



So the question remains, how much heat can this motor shed before hitting 100c with a huge battery? Let's look at the closest sized motor we can find on ebikes.ca simulator:



Looks like the eZee will overheat during a long ride at 116 watts of heat.

I think it would be safe to assume this motor can handle 100w of heat.. so at what speed do produce 100w of heat?



Looks like we have a 30mph capable motor. Same case in a 27.5" because the difference in efficiency is tiny.

Here's some other thoughts...
The wiring on this motor is rather thin. I see these z9 harnesses being rated for a burst current of 55A phase. I'm betting they have 18 gauge wire considering how thin they are.

If that's the case then we are losing 2.43% of our power during that 55A load. We can cut that power loss down to 0.61% by using 12AWG out the axle. The wire can now suck a few watts of heat out of the motor, because it's not being heated during acceleration, except by the motor.




The Shengyi SX2 has an identical layout to the MAC; the motor stator faces the cassette side of the case, and a majority of heat is shed through the axle. If we could somehow rig up heat sinks that sit on the end of the axles, and do this wire thickening trick, I think we could get enough thermal headroom to sustain 31mph by removing 10W of heat.

Impressive motor, certainly capable of the 30mph for very long periods of time, i want one
OP, thanks for inspiring me to look further into this motor.

 

[tnoller5972]

Pretty much all outrunner are built the same way. The sx2 is much smaller compared to those motors but where it shines is it's peak efficiency. Most motors hope to be peaking at 80% and this motor if I remember correctly has 87% efficiency peaks so even though it's small and not sure power/torque dense, it's quite efficient. Only real world application/tests will truly let you know though how it will perform for your setup though.

Also your test used a fast wind in the 27.5 in wheel, it should be a standard wind. Torque will go up, heating should go down and speed should rise as fast winds in large wheels need high phase amps to drive. Also make sure when comparing graphs to have throttle output at same amount for more accurate results.(Both at 100% throttle rather than one at 100% and one at 20%)

 

[tnoller5972]

Also anything over 50 to 55 phase amps will start to damage clutch, shread gears and heat hub very fast. Fast wind could probably take more but idk about 90+ phase amps.

 

[neptronix]

I picked the fast speed winding because you can't simulate field weakening in the simulator to achieve high speeds in the 24" wheel. I wanted to isolate the comparison to differences in wheel diameter as much as possible. If we compared two different windings, we'd skew the data too much, so a small voltage differential was used instead to help equalized the speed.

I would need to use 72v to get the speed i want on a 24" wheel, which i'm not willing to use.

The highest efficiency i saw while playing with the simulator was 88.2%, and this happened with the standard winding, which seems to have a .5% peak efficiency advantage over the fast winding.

If i used field weakening to increase the standard winding's speed to up to 35mph, i'd need massive field weakening.. i'd be throwing out a couple % efficiency at the controller; not sure if we lose efficiency at the motor level, but, overall this is efficiency negative and i want to avoid that. The fast winding for 24" makes the most sense.

Only real world application/tests will truly let you know though how it will perform for your setup though.

Aware of this, been using the ebikes.ca sim for over a decade and find it is extremely close to reality every time.

Also make sure when comparing graphs to have throttle output at same amount for more accurate results.(Both at 100% throttle rather than one at 100% and one at 20%)

I think you missed a detail. The point of that comparison was to exactly match the speed and find out what the heat production would look like in two different wheel sizes.

Also anything over 50 to 55 phase amps will start to damage clutch, shread gears and heat hub very fast. Fast wind could probably take more but idk about 90+ phase amps.

The fast winding should produce equivalent torque/power as your standard winding if fed ~80A phase.

I'd like to allocate the additional power potential i get from the 24" wheel towards increasing thermal headroom, so basically i'd be running effectively the same tune you recommended.

 

[tnoller5972]

If you want to simulate FW click on show advanced under throttle slider to increase kv in increments. Even then though it doesn't 100% simulate it, more of an idea. Going from 7.9kv of standard wind to around 10kv of fast doesn't simulate FW. It simulates a fast wind motor. With FW your kv might go from 8kv to close to 9kv if even that much. You also have full torque as it doesn't kick in till high speed.

Not really the same tune as the thing is your not feeding 80a into a z9 plug safely lol. 55a is the cap without melting and cooking things. Phase current heats the motor so yeah it would perform the same as far as for torque output but the motor would melt almost instantly. The point of the fast wind is to trade off torque for speed, yeah you can just up phase current to make up for it but that makes heat and there is a limit. 55a being that limit. A more appropriate controller for the test would have been a baserunner though only goes up to 52v.

 

[tnoller5972]

Also field weakening does cause efficiency loss in motor as stated above but as mentioned that's where it's okay to run some as the sx2 is very efficient to begin with so a small hit isn't so bad. Over do it and it will heat up fast with even with no load.