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I'm a newb, and I got a amp question

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Old 03-15-2006, 05:30 PM
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nuclear_cv
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Default I'm a newb, and I got a amp question

I got a 1750 kv brushless motor and a 2150 mah 3s1p li-po battery and I would like to know how many amps will the motor pull. I'm a cheap ******* and I was looking through ebay and I saw this...

[link]http://www.warmyourfloor.com/index.asp?PageAction=VIEWPROD&ProdID=2[/link]

I'm just wondering if this sort of volt meter will do the job, thanks!
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Old 03-17-2006, 11:28 AM
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Matt Kirsch
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Default RE: I'm a newb, and I got a amp question

Without a propeller, it won't pull many Amps at all, maybe 1 or 2....

The Amps a motor pulls on a certain voltage will vary with the propeller size. There is no easy way to calculate by hand, so you'd need a good set of manufacturer application charts (not always available) or a motor calculator software such as Motocalc.

If you have the manufacturer's specifications on that motor, either on a website or in the instructions that came with the motor, you can usually look up the maximum Amps that the motor is rated for. That will give you an idea of how much the motor COULD draw, if you don't overload it.

That meter you listed is only rated to draw about 2 Amps. Unless you're testing micro indoor flyers, it is not suitable for testing Amps in electric power systems by itself. You want something like a WattsUp meter or an Astro Whattmeter. FMA Direct sells a shunt that would allow you to use the inexpensive meter you listed to test high currents.
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Old 03-17-2006, 04:01 PM
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jdetray
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Default RE: I'm a newb, and I got a amp question

Hi Matt-

These inexpensive yellow DMMs (digital multimeters) are limited to 200mA DC through the rotary switch, but they have a separate socket for measuring DC current up to 10A. So they will work for small-to-medium sized electric power systems.

If you look at the photo of the meter, you'll see the separate 10A DC socket above the other two sockets.

Even so, a proper meter like the Astro-Flight Whattmeter is far better. The convenience alone makes the whattmeter-type meters worth their cost.

- Jeff
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