Castle 2650 Motor on 6s Lipo

[bruce750i]

Sometimes I just want a higher rev setup. It sounds more impressive and makes the TX trigger feel like it has a higher resolution.

[nuz69]

Originally Posted by asheck

I guess my bottom line is this. He said the 2200 would have smaller amp spikes, then the 2650, when they were the same speed. From my experience this is not true, I found the smaller higher KV motor to draw less amps, when geared for the same speed. .

It's true only if the motors have the same size. Here, between the 2200Kv and the 2650Kv, the difference does not come from the windings but from the length of the rotor (both motor have same windings 1Y and same windings thickness).
Therefore gearing for the same speed, both motors will draw the same amp, but as the 2200Kv will spin lower, there will be less magnetic losses in it, so it will be more efficient and draw a little less amp for the same power.
The longer the motor is, the cooler and more efficient it generally runs, that's true if the motors have the same design and windings.
Given that, a 1520/1Y geared for the same speed will run even cooler than the 1515/1Y.
But its true that for the same size, the lower Kv will need higher voltage. For (simplified) example you can run the 1512/1Y at 120A but not the 1512/1.5Y which is rated at only 80A (more wires turns, less thickness, but lower Kv...).
More Kv means less inductance, meaning more amp spikes (lower response time). "Torque" is sometimes judged at the feeling of the driver, it should be better to talk with torque per amp. Less Kv means more torque per amp.
Hope it's clear

Here, between the 2200Kv and the 2650Kv, the difference does not come from the windings but from the length of the rotor (both motor have same windings 1Y and same windings thickness).

My example is stemming from a 1410 compared to a 1415. So both 1y

Here's my 1415 on 3s, running 49mph, on 3s in my Pede 4x4



Here's my 1410 running 49mph on 3s.



Here's my 1415 on 2s running 30mph



Here's my 1410 running 33mph on 2s



The max amps, and the average amps are both higher, with the bigger motor. Even though the speed is the same or lower. Now, it's all pretty close, so I would assume the 2650 and 2200 would be even closer. But I logged probably 10-15 runs with each setup, and the 2400 always drew more amps, and averaged more.

You can't judge efficiency off temps when you are dealing with 2 different sized motors, as the bigger one will always run cooler, given the same load and efficiency. IOW just because the bigger motor is cooler, does not tell you that it is more efficient.

[snellemin]

Nice graphs Asheck. Can you do a run with the 1415 motor with same gearing, but lowered timing. Say 0 and 5 degrees and post up the graphs. Please, pretty please, with a malt ball on top.

I'll see what I can come up with :)

This is not the same setup as the above graphs. It's my Slash 4x4 1415 with a SV2 Pro, I added a cap and bec, radared at 45mph. Also I wasn't near as consistent with the driving on the 5, you can see the 0 had more steady runtime. So if you take out the down time, it had a higher average. I also did not run the same battery in each, but they are matching packs, I'm gonna switch them around, and try to be more consistent.

5* timing



0*


Temps were within a few degees of each other, and the 5* felt better. Pulled a few wheelies with it, couldn't on the 0.

[snellemin]

So would you say that 5 degrees of timing is most efficient in your setup?

At the moment, I don't believe I'm educated enough to say. :) I can say, that the 5 timing sure seems to have more power then the 0, and had higher amp spikes , so it would seem that efficiency would be hard to determine, due to different performance.

But I'm doing another run, and it's more confusing. Geared down to 17/54, and pulled 119 amps. WHY!! :)

[snellemin]

Originally Posted by asheck

At the moment, I don't believe I'm educated enough to say. :) I can say, that the 5 timing sure seems to have more power then the 0, and had higher amp spikes , so it would seem that efficiency would be hard to determine, due to different performance.

But I'm doing another run, and it's more confusing. Geared down to 17/54, and pulled 119 amps. WHY!! :)

You might of have some cat hair in between the gear mesh, causing the increased friction. Hence the higher amp draw.

Maybe you had more traction at one point. Was your avg ampdraw about the same or less?

17/ 54 gearing 0 timing , same battery for both runs, performance was very close.


5 timing.



Take from it what you can :)

You know I am learning, more then max, it is all about the averages.

[snellemin]

I have a theory. Lower gearing produces more instant torque, which you can see by the peak reading. Lower gearing also equals to a lower load on the motor, hence the lower avg reading.

Just a Tomballion theory.

[nuz69]

I always have longer run times with my 1520/1Y on 4S in my buggy than my 1515/1Y on 4S both setup geared for the same speed. I can't explain why you found the contrary with your results ^^
But it's true that cool does not mean efficient.

geared for the same speed.

Are they geared for the same speed, or running the same speed? I always confirm speed, just in case.

I have a theory. Lower gearing produces more instant torque, which you can see by the peak reading. Lower gearing also equals to a lower load on the motor, hence the lower avg reading.

Could be. I've seen lot's of stuff with the datalogger, that I haven't worked out yet. Especially when it comes to bursts.

[fastbaja5b]

Ok, so to explain it to a dimwit like me, I have my SC8 with a Castle Neu 2200 geared for 40mph on 4s Lipo. If I go up to 5s Lipo, but adjust my gearing down so that I am still geared for 40mph, will my run times increase and amp draw decrease, or can you go too far as to undergear the motor?

[suicideneil]

Originally Posted by fastbaja5b

Ok, so to explain it to a dimwit like me, I have my SC8 with a Castle Neu 2200 geared for 40mph on 4s Lipo. If I go up to 5s Lipo, but adjust my gearing down so that I am still geared for 40mph, will my run times increase and amp draw decrease,

That is conventional thinking, yup, and most graphes & reports I've seen support it- more power in the system and less load on the motor should result in less current draw and longer runtimes.

or can you go too far as to undergear the motor?

Also true- there is obviously some le-way regards the perfect gearing but BL motors will tend to run hotter if they are underloaded, since they are able to hit max rpms quickly and stay there. I believe Patrick referred to motors liking partial throttle & escs liking full throttle for maximum efficiency too, so it figures that a motor running full throttle alot of the time will run hotter than the esc will- just gotta try and strike a balance between motor kv, motor size, input voltage & gearing- hence why this hobby is so damn complicated and frustrating at times