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Wobble

Motors & Amps

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I've got 3 18k FC-130 motors here all pulling very close to the same revs at 12v. Two are drawing 1.5amps while the other is drawing 2.5amps. Does this mean the one pulling the most current should be the quickest on the track? They've all been run in in water and dried thoroughly and lubed.


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I would guess the one pulling the most amps will be a dud.

 

Just saying

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John Warren

Slotcars are my preferred reality

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I would guess the one pulling the most amps will be a dud.

 

Just saying

 

Thanks John, the opposite to what I imagined. Might be a while before I can test the other 2 but hopefully they make the car quicker.


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Hi Wobble. If these are RTR motors they seem to be drawing a lot of current. Are they all faulty? My understanding is RTR motors normally only draw about 0.5 to 1am. Sure there are better qualified people out there. Hopefully they will come forward. Regards Chas Le Breton

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Bram

 

As Charles said, that seems like a high current draw, even at stall.

Even 1.5 amps at 12 volts is an 18 watt motor, 2.5 amps is a 30 watt motor.

I don't know of any motor that could be vaguely described as "an 18k FC130 motor" which could draw that much current even at stall without sending out smoke signals.

 

We need more information to even hazard a guess or give an opinion.

 

Firstly, - you don't say what the motors are, or if they are the same type of motor.

- The term "18k motors " always makes me feel like someone is dragging fingernails across a blackboard, it doesn't have any basis in the real world as such.

(Mostly people use it to describe the old mabuchi 'black stripe' motor used in Scalextric and some Fly cars for many years)

But they have pulled way more than 18k for at least 12 - 14 years. Most I have tested, pulled in excess of 20k, and 21 - 23k is common. They did however have so little torque, they had way less grunt than say a Shark 20k or Slot.it 21k orange bell.

- You also need to say what basis you obtained the current draw.

- Was it at stall ?

 

When you ran them in water, did you add anything to aid lifting of gung out of the gaps between the comm sections?

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Walks upright Unaided  *  Ties Own Shoelaces  *  Can Mispronounce Own Name In Five Languages  *  Mostly Aims Rattle Cans Away from Self
 My Track Oakland Raceway V2     Our Club  HMBRC     

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Maybe the gauges on my power supply unit are a bit optimistic but then it wasn't overly expensive even for new. The 2 motors drawing less current are Pioneer QS and 1 is new. The other (drawing more current) is a SRP 18k which I tried in my Bartlett Camaro and it is 0.2 sec faster than my Galaxie on Wazzas track and lifts the front wheels when gunned. Motors were all running at 12v no load. As far as the water treatment goes, it was lukewarm with a couple of drops of detergent.

 

edit:- I just figured as a comparison to run a couple of NSR classics with Shark 20's and as well as revving a bit higher they are drawing about the same current as the SRP 18k so the gauge is definitely not the most accurate.

Edited by Wobble

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Ah no. Forget using a power supply to get data Bram. You really need a multi meter.

 

Likewise for the RPM, if you download an app called GIRI, you can test motors as accurately in most cases as using a non contact tacho.

- Sometimes you will need to remove gearing from car, as it can interfere with the data that the app picks up through you phone's microphone.

 

You can use this spreadsheet to calculate the actual power of the motor in watts, and determine relative power, and get a feel for best gearing for each in your situation

Motor Power Calculator

 

The spreadsheet is pre-loaded with some common examples. Just replace the figures there and description with your own motors.

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Walks upright Unaided  *  Ties Own Shoelaces  *  Can Mispronounce Own Name In Five Languages  *  Mostly Aims Rattle Cans Away from Self
 My Track Oakland Raceway V2     Our Club  HMBRC     

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Thanks for that Mark. I think a multi meter might be a bit of overkill for me if all I want to do is measure the current draw of a FC-130. I think I'll resort to doing it my usual way and just find out which is fastest on the track although that won't happen for a while either.


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