RC brushless motors Avery high current draws. RC brushless motors and ESC with very high current ratings from small motors having 16A draw to ones with 60 to 70A current draw. The specs also says peak current draws unto 200A are possible on certain motors.

Shouldn't these high currents heat-up and burn the motor? The only motors I've seen draw such large currents are starter mots that draw anywhere from 100-200A. But since they are very big they dissipate the heat quickly plus they run only for few seconds.

 

There is no way a ESC or motor draws that current, the LiPo battery is not capable of that current, one thing misleading on RC is the a figure such as 2500Kv it is not 2500 kilo-volts but 2500 x battery voltage, so 2500 x 7.4v = 18500rpm.
Max.

 

There is no way a ESC or motor draws that current, the LiPo battery is not capable of that current, one thing misleading on RC is the a figure such as 2500Kv it is not 2500 kilo-volts but 2500 x battery voltage, so 2500 x 7.4v = 18500rpm.
Max.

Its the specs of the ESC that made me confused. I came across the specs of one of them which stated it can run continuously for 200A which kept me thinking. Also, does RC airplane motors draw large current?

 

Also, does RC airplane motors draw large current?

It cannot run on a greater current than Its typical LiPo battery can supply.
Max.

 

As I understand it the motors are far more efficient than the typical brush type or common larger induction motor so they have the advantage of simply having less actual energy losses to deal with.

On top of that most have full air flow cooling both through and over them as well which helps pull a lot more additional heat out that other designs of motors can't do.

So take a motor that's 90 - 95+% efficient rather than 75 - 80% plus has 2x or better air cooling capacity than any other motor its size and you can put some rather impressive power through them without burning up.

 

which stated it can run continuously for 200A which kept me thinking.

You may see an ESC that states 200a etc, but generally this refers to very short transients, and even then I am susceptible to the claims.
Do you have a link to one that states 200a continuous?
Max.

 

You may see an ESC that states 200a etc, but generally this refers to very short transients, and even then I am susceptible to the claims.
Do you have a link to one that states 200a continuous?
Max.

200 A continuous, 250A peak



https://hobbyking.com/en_us/turnigy...VA16GCh1F0gkIEAQYAyABEgK8X_D_BwE&gclsrc=aw.ds

 

You wanna show me the battery that will support that and an aircraft that can carry it!
They only supply a very short burst, if your lucky.
Max.

 

You wanna show me the battery that will support that and an aircraft that can carry it!
Max.

Umm, who said aircraft? The web page clearly says boat.
I don't see aircraft mentioned anywhere on the thread.
These can be used on skateboards, eBikes and Boats (even som RC Cars)


Airplane ESCs to out around 130 to 150A

https://hobbyking.com/en_us/platinum-130a-hv-opto-v4.html
Peak is 160A on this one, 130 continuous.

Plenty of planes.

 

HobbyKing makes cheap Chinese Turnigy junk! That ESC is made for a huge competition SPEEDBOAT, not an airplane.
My American designed RC airplanes use an ESC that shuts down when the motor is stalled and has a current more than 6A.

 

Also, expect to use 3 x 65A batteries.

10,000 mAh at 65C continuous and 130 surge.

 

Note:

aluminum water cooled heatsink for better thermal dissipation

These things really are designed for outrageous currents.

A 10AH 30C battery can supply 200A for 3 minutes. I guess they are for short races

Bob

 

200 A continuous, 250A peak

When I have had to run 200amp cables, the minimum I could get away with is 4/0 cable, .46" dia.
Max.

 

When I have had to run 200amp cables, the minimum I could get away with is 4/0 cable, .46" dia.
Max.

Normally yes but given the typically extremely short runs (~3" - 6"s) RC power supply systems have between major components they can cheat the heck out of things and go way undersized on the wiring.

My brother is into that stuff big time and he has controllers that pull 100+ amps through nothing but 10 ga fine strand silicone jacketed wire.

It's similar to how in a mobile application low voltage power systems (vehicles, heavy machinery and the like) its allowable to use a 4 ga cable for a starter that draws 200 - 300+ amps or an alternator that puts out 150 - 200 amps.
The length of the runs and duty cycles at those currents are short enough that the combinations of the voltage drops and related resistive heating effects are within the limits of the system and components to safely handle.

 

When I have had to run 200amp cables, the minimum I could get away with is 4/0 cable, .46" dia.
Max.

The RC community also uses 100% silicone insulation with continuous working temp of 200°C.
It is very difficult to get to 200C in front of a fan. Most users also fully expect to change parts on a regular basis so nobody expects 1000 hours or more of use.

Fuse current for copper is about 330 A in still air.
Copper melting point is (1085°C). Luckily lots of air flow is available in most applications.

 

You may see an ESC that states 200a etc, but generally this refers to very short transients, and even then I am susceptible to the claims.
Do you have a link to one that states 200a continuous?
Max.

Hi,
This is what I came across a post for a brushed motor ESC:
"Taken from the traxxas site regarding the XL-5 (watersealed) ESC
Input voltage: 4-8 Cells (4.8 to 9.6 Volts DC)
Case Size: 1.23"W x 2.18"D x 0.61" H
Weight: 2.44 Ounce
Motor Limit: 15-turns** (540 Size)
12-turns** (550 Size)
On Resistance Forward: 0.007 Ohms
On Resistance Reverse: 0.014 Ohms
Peak Current - Forward: 100A
Peak Current - Reverse: 60A
Braking Current: 60A
Continuous Current: 14A"

and for the brushless ESC:
"Turnigy Monster-2000 200A 4-12S Brushless ESC
Spec.
Cont. Current: 200A
Burst Current: 230A
Battery: 4-12 Cell Lipo / up to 38 Cell Ni-XX
BEC: Nil
Size: 125*60*38mm
Weight: 293g"

 

Umm, who said aircraft? The web page clearly says boat.
I don't see aircraft mentioned anywhere on the thread.
These can be used on skateboards, eBikes and Boats (even som RC Cars)


Airplane ESCs to out around 130 to 150A

https://hobbyking.com/en_us/platinum-130a-hv-opto-v4.html
Peak is 160A on this one, 130 continuous.

Plenty of planes.

Hi,
even though they are for short durations, what surprised me was that how these tiny hand sized motors could pull such high currents. A big heavy mot makes sense. But something this small caught my attention.

 

The RC community also uses 100% silicone insulation with continuous working temp of 200°C.
It is very difficult to get to 200C in front of a fan. Most users also fully expect to change parts on a regular basis so nobody expects 1000 hours or more of use.

Fuse current for copper is about 330 A in still air.
Copper melting point is (1085°C). Luckily lots of air flow is available in most applications.

I agree with what you said. So, its the large amount of air flow and frequent maintenance that keeps these things running I guess.I was into these RC stuff sometime ago, have to say its kinda a costly affair if you are really serious with the stuff and look for high quality parts.

 

Hi,
even though they are for short durations, what surprised me was that how these tiny hand sized motors could pull such high currents. A big heavy mot makes sense. But something this small caught my attention.

I would be interested to see Documented tests.
My alternator on my vehicle is rated at 150amps, I imagine how long it would last if subjected to this for an extended period.
I have played somewhat with these types of motors, although not this high a current, and the numbers tend to be misleading.
Max.

 

I would be interested to see Documented tests.
My alternator on my vehicle is rated at 150amps, I imagine how long it would last if subjected to this for an extended period.
I have played somewhat with these types of motors, although not this high a current, and the numbers tend to be misleading.
Max.

The biggest killer of these motors is the insulation at high temps and the bearings under these extreme loads. Someone put a quadCopter drone together that can do near 175 mph. Think about the prop tip speed, rpm and pitch to make 175 mph on a quadCopter sized prop (16" or so).