Getting cold feet... ESC+Motor advice needed

[Reyhn]

So, I myself have a SCX10 Rubicon all stock, but I don't have much experience with crawling (I have a Slash 4x4, though). The motor is a bit too week for my taste, but the top speed (a bit faster than walking speed) is fine.

My uncle got immediately hooked the first time he tried it, so he asked me to pick out a SCX10 II for him (he has no experience with RC at all). The intention is to use it mostly for crawling, scaling, some trailing but no speed runs nor mudding.

Since we both want more torque, I presented a couple of ESC+motor options for him, and he obviously went for the biggest one:

Tekin RS Gen 2 (ESC) + Tekin ROC412 3100kv (motor) + 2S batteries

Now, I know this is a great combo, but how much overkill is it?
It's really hard to determine from watching YouTube (we don't have much crawlers around here, unfortunately).

Is 3100kv + 2S too much?
What about 3100kv + 3S?
Does 2300kv + 2S provde walking speed and plenty of torque? We figured that it is not unlikely that an upgrade to 3S will be in the near future.

I'd appreciate you telling me if this combo is too insane, or if any of the other options is better aimed at us. We don't know what we're doing here (: since our only frame of reference is the standard Axial 27T motor on 2S, which is way to weak.

[Brutus279]

3100kv on 2s is a great compromise. You will have a lot of torque at low RPM and some wheels speed. If you later want to push the machine a little further (witch I don't feel like it ether) you would always have the possibility to run a 3s pack with a UBEC installed.

Personally I chosen to go with a Tekin Brushed Combo, but the ROK412 3100kv / RS Gen II combo was my first choice if I decided to go brushless. Their is plenty of RC top speed calculator on the net that will let you calculate axle torque and top speed. If you want a more precise resolution at low speed, try to play with exponential on your transmitter. Expo can make a 4000kv precise at low speed while keeping 100% of its speed at full throttle.


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[jwall046]

I have roc412 on 2s and 3s in wraith and bomber (2.2 wheels). Stupid power and part breaking ability. Need throttle control for sure.
I have scx-10 II with tekin 35t brushed and love it!
Faster than walking for sure but very controllable power on 3's.
I'm most likely going brushless Holmes hobby with a lower kv than 3000 for a little more wheel speed and torque.
I'm not looking for crazy unnecessary wheel speed like 3100kv gives.
Not sure if this helps.
But id also look into calling Holmes Hobbies for a very good idea

[CM9000]

the lower the kv the more torque. the higher the kv the less torque. the more cells the more power. a 21300kv on 3s would be good. you could gear down and put a 4s in it but you would limit yourself by how many mah's you get. you cant beat a good brushed setup though either. but.. you compromise how many times you need to get it rebuilt. and well.. a brushless setup is more efficient in terms in amp draw and battery power loss.

all in all id say a 2300kv on 3s would be perfect.

[mikemcE]

I love my HD3100 on my BLE, run on 3s, geared for crawling.... gobs of torque


HANG UP AND DRIVE !

[CM9000]

like johnrobholmes says... volt up! gear down!

[svt923]

Originally Posted by CM9000

the lower the kv the more torque. the higher the kv the less torque.

Not for brushless motor. When choosing between a 2300kv and 3100kv ROC412 (assuming same voltage for both), the only thing you really need to choose is how much wheelspeed do you want; everything else will be practically equal.

Originally Posted by JohnRobHolmes

Lower KV brushless motors DO NOT produce more torque. DO NOT!!! A motor is limited by the size and materials, there is no magic method to extract more torque. So if you want more torque, don't get a lower KV and expect a wild change.

[Reyhn]

Thanks a lot for the input, everyone!
From what all of you say, I gather that neither combo is too crazy, although I better be prepared to repair. (:

Originally Posted by Brutus279

3100kv on 2s is a great compromise. You will have a lot of torque at low RPM and some wheels speed. [...] Personally I chosen to go with a Tekin Brushed Combo, but the ROK412 3100kv / RS Gen II combo was my first choice if I decided to go brushless.

Thank you! That's reassuring!

Originally Posted by jwall046

I have scx-10 II with tekin 35t brushed and love it! Faster than walking for sure but very controllable power on 3's.

I've read about that motor as well, and it seems very good, but I've gotten the impression that brushless is somewhat easier for beginners.

Originally Posted by jwall046

But id also look into calling Holmes Hobbies for a very good idea

Actually, the runner-up was the HH TrailMaster Pro BLE 540 2700kv + TrailMaster Pro BLE (ESC). It also seems to be a great combo (too a much lower price), but I don't know how it compares to the Tekin combo?

Originally Posted by CM9000

all in all id say a 2300kv on 3s would be perfect.

I know you mean well, but that didn't make it any easier. (;
For sure, after watching YouTube, I was considering this option as well. Personally, I would have started out with the 2300kv + 2S, and if I felt the need I would have upgraded to 3S. It looks like 2300kv + 3S is about the same as 3100kv + 2S, the difference being the options in changing cells. Slow down with the 2300kv or speed up with the 3100kv.

Man, this is a tough choice...!

[Reyhn]

Originally Posted by svt923

Not for brushless motor. When choosing between a 2300kv and 3100kv ROC412 (assuming same voltage for both), the only thing you really need to choose is how much wheelspeed do you want; everything else will be practically equal.

Woah!! (Referring to the Holmes-quote.)
I did not know that! I thought it was the exact opposite: lower kv == more torque.

Thanks for the quote! Really!

[CM9000]

so a 770kv outrunner has the same amount of torque as a 3100kv inrunner? both non sensored.

[calcagno45]

Originally Posted by CM9000

so a 770kv outrunner has the same amount of torque as a 3100kv inrunner? both non sensored.

He's referring to motors with different kv's but in the same can size will produce same torque. So Holmes PP 2700 and 3500 will produce same torque values.


See post #64, Axial SCX10 ii review by Holmes Hobbies

[The Doc]

I now run all RX8's in my rigs, it eliminates the external BEC's and it will handle all the motors, I run the 412 3100 motors and with the new Tekin program it now acts almost like a brushed motor.

No overheating probs and the internal BEC can handle the big torq servos.

[CM9000]

Originally Posted by calcagno45

He's referring to motors with different kv's but in the same can size will produce same torque. So Holmes PP 2700 and 3500 will produce same torque values.


See post #64, Axial SCX10 ii review by Holmes Hobbies

in the same can.. a lower kv has more torque at start up. hands down.

im not here to argue though. im here to simply suggest that a lower kv with a 3s seems better at startup.

[calcagno45]

Not here to argue either. That was always my impression as well, lower kv = more torque(as long as you volt up).