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Oct 08, 2019, 12:25 PM
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Need help about choosing right motor.


Hi,
I decided to make a RC car and don't know anything more than a few things, so I need your help. I will do 1/10 rc car and not decided it's type but it can be buggy or truggy. I have a 3s 4000mah 30c battery, so it should work with 3s. About prices, I don't want to spend more than 25$ for a motor. Of course if there is a big difference between 30$ one, I can buy that too...

After some researching, found this motors:

Racerstar 3660 Motor (KV ?)@ Banggood
Racerstar 3670 Motor (KV?) @ Banggood
Turnigy XK-3650 5400KV Motor @ HobbyKing
Surpass 3660 (KV?) Motor @ HobbyKing

I prefer buying them from Banggood, because they have custom fee insurance.
If you have a different idea please share. Thanks a lot...
Last edited by bersan1; Oct 09, 2019 at 11:22 AM.
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Oct 08, 2019, 11:19 PM
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bill_delong's Avatar
pick the car first, then select the proper motor for the car

around 2500-3000KV will do nicely on 3S

1/10 Truggy like the TEKNO ET410... I would go with a 3660-3000KV on 3S if it were me
Last edited by bill_delong; Oct 09, 2019 at 10:25 AM.
Oct 09, 2019, 10:06 AM
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Originally Posted by bill_delong
pick the car first, then select the proper motor for the car

around 2500-3000KV will do nicely on 3S

1/10 Truggy like the TEKNO ET410... I would 3660-3000KV on 3S if it were me
Well, here is my car (frame?): https://www.thingiverse.com/thing:42198
I will print it with 3d printer firstly. Then I will upgrade differentials and gears to metal. Cause I want to be sure about I enjoy RC car hobby so not wasting my money.
So what should I do/buy? Or printing it with plastic is a bad idea even for a short time?
Oct 09, 2019, 10:33 AM
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bill_delong's Avatar
That article linked to the electronics he used for his project, though the link is currently broken, I am familiar with that motor which is a 540 size or 3650 can 4000KV on 2S.

Since you want to run 3S, I would go with 4000*2/3 = 2667KV motor

The closest motor that I can find is this 3100KV motor here:

https://www.banggood.com/Surpass-Hob...r_warehouse=CN

*** UPDATE

I also found a 17.5T (2400KV) motor here that will be more conservative and less likely to damage your drive train on 3S power:
https://www.banggood.com/Surpass-Hob...r_warehouse=CN
Last edited by bill_delong; Oct 09, 2019 at 10:41 AM.
Oct 09, 2019, 11:39 AM
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Quote:
Originally Posted by bill_delong
That article linked to the electronics he used for his project, though the link is currently broken, I am familiar with that motor which is a 540 size or 3650 can 4000KV on 2S.

Since you want to run 3S, I would go with 4000*2/3 = 2667KV motor

The closest motor that I can find is this 3100KV motor here:

https://www.banggood.com/Surpass-Hob...r_warehouse=CN

*** UPDATE

I also found a 17.5T (2400KV) motor here that will be more conservative and less likely to damage your drive train on 3S power:
https://www.banggood.com/Surpass-Hob...r_warehouse=CN
If I understood correctly; I shouldn't buy a motor that has too much kv, cause it can give damage to drive train, right? However, can I buy and use high kv one (for being future proof), if I limit throttle output (eg. %75)?
Can I get bigger motors than he used (3660, 3670) or bigger motors will be incompatible/make it worse the vehicle?
And the sensored motor seems like a bit expensive
Oct 09, 2019, 01:27 PM
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bill_delong's Avatar
I would not recommend dialing back the EPA to 75%, yes it "CAN" be done and chances are your motor temps will do just fine, but you'll need to invest in a higher quality ESC that is rated considerably higher in order to absorb the extra power. You will more than likely cause the ESC to fail sooner than if you select a proper size motor in the first place. As an example, my prediction would be shortening the ESC life to 6 months instead of lasting several years.

You will want to stick with a 3650 size can with a 3.17mm shaft, most 3660 and larger cans come with 5mm shafts which will be very impractical in finding 48P pinions, yes it "CAN" be done, but the larger 4 pole motors will produce significantly more torque such that even if you dial back the EPA, you would need to dial back the punch rate, throttle speed and expo to help minimize the risk of tearing up your drive train.

If it were me, I'd keep it simple and select the motor that the car was designed to run, it will only save you from frustration later

I did find a 3650-2600KV motor here that would be perfect for your application on 3S:
https://www.ebay.com/itm/kust10-1x-B...EAAOSw~CFY6zym
Oct 09, 2019, 02:05 PM
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You're right. Stay with 3650 seems the best option as a beginner. Well, what I should do about kv? Should I stay with 2600KV or there is no different if it's 3650?
Oct 09, 2019, 02:18 PM
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If it were me, I would limit to the following 2 options:

1) 3S - 2600KV
2) 2S - 4000KV

You will get the same power with either of these setups, however 3S will be more efficient to where all of your electronics will last longer and you will get roughly 20% longer runtimes given the same watt hour capacity between 2S or 3S application.

I would not go any higher than 2600KV for 3S if it were me, otherwise just asking for trouble
Oct 09, 2019, 02:30 PM
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Like which problems will happen (for learning)?
Oct 09, 2019, 09:13 PM
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bill_delong's Avatar
anywhere from overheating/damaging your electronics to damaging the drive train, etc... can't predict everything, best bet is to go with what the OP recommended in his article that you linked, or something close to it
Oct 09, 2019, 11:08 PM
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Hmm, makes sense. I don't want to lose my car. Eventually, it's plastic! How I can cool my motor better, heatsink or heatsink with a fan? Or just it doesn't need it?
Oct 10, 2019, 08:51 AM
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Normally a fan shouldn't be necessary if you gear it properly, more info here:
What gearing do I need to run for upgraded electronics in my car?
Oct 10, 2019, 09:54 AM
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So, I will try and find best gear for my vehicle. Seems like everything is fine now. Thanks....


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