Does BLDC manufacturer website Max Current = Stall Current?

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1

When buying hobby BLDC motors, what specifically do manufacturers mean by Max Current and Max Power?

Are these values for continuous operation taking heat into account? Or does max current mean stall current on these websites.

EXAMPLE:
Turnigy D5035-125KV

Thanks so much! :smiley:

2

Hi @Storm78
45A can’t be stall current, since they recommend a 220A ESC.
Furthermore, they say the resistance is 90mOhms. (single coil resistance?)
Theoretically the motor can draw maxCurrent= 8 to 12 times 4.2V / coil resistance (~400+A)

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:slightly_smiling_face:Thanks @o_lampe for the answer! So in that sense, max power and max current are the continuous operation currents provided.

I will be using an ODrive and machining my own shaft to extend behind the motor as well for an encoder. I was expecting to limit my current to 90A or so.

If they recommend a 220A vesc… What kind of ballpark peak current do you think this motor can handle? :astonished:

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That’s hard to say. There are the usual weak points, that tend to fail first, due to overtemperature:

  • The insulation of the connector cable (PVC or silicone?)
  • The laquer of the copper winding (single or double coated?)
  • Then there are two types of laquer:
    low temp melts when soldered
    high temp has to be scratched off the wire before soldering

A long term problem is the max. temperatur of the Neodym magnets, they loose their strength, when getting to hot.

Keep the core temp below 90°C and it lasts forever

5

Thanks for the answer again!

I understand the weak points which usually limit continuous current, and of course peak current as well. But I believe you can safely provide extra current for about a second or less. I was just curious how much more if there was a number people follow.

For my own purposes I will stay below continuous, but right before I am done with my robot I might get more adventurous haha. So I might push 10 or 15 amps more for a a very short amount of time.

I usually measure the outside of the motor, measuring the inside makes more sense. I wonder if thermocouple integrated motors do this? :thinking: