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ESC's & LiPo's

Old 07-19-2008, 02:01 AM
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dragus359
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Default ESC's & LiPo's

So this isn't really specific to the Axe, but I was wondering if a 25A brushless esc can handle an 11.1V 20C LiPo. And anyone, please feel free to explain to me how to match up the C rating to an esc and/or motor, cuz I've just kinda been taking blind guesses, and so far I've gotten lucky. I'm bound to get burned soon though if I keep it up lol.
Old 07-19-2008, 11:11 AM
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Default RE: ESC's & LiPo's

Voltage has nothing to do with the current (A) that an ESC can carry. The documentation for the ESC you're considering should quote the Voltage limits for it.
Old 07-19-2008, 06:44 PM
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Default RE: ESC's & LiPo's


ORIGINAL: dragus359

So this isn't really specific to the Axe, but I was wondering if a 25A brushless esc can handle an 11.1V 20C LiPo. And anyone, please feel free to explain to me how to match up the C rating to an esc and/or motor, cuz I've just kinda been taking blind guesses, and so far I've gotten lucky. I'm bound to get burned soon though if I keep it up lol.
Let's see if we can help you see...

First off the motor (and the associated electronics, receiver, esc, etc.) will pull a certain amount of current (amps), you'll want to take the max (and the motor will pull the most, the rest is very small in comparison).

The 'C' rating on the battery is the must current the battery can supply. So if you have a 20C 1000mAh battery (mAmp Hour), it can supply (at most) 20*1000 = 20000 mA or 20A. You draw current from a battery, it never "forces" current. So if you heli only requires 18A, it will only get 18A

The ESC will have a maximum voltage rating and current rating it can handle (supply)


So, based in what your motor requires, you size a battery so that it will supply that much current. That's a minimum. The safe route would be to get a battery that can supply more then what is required. The ESC is similar. You make sure it can handle the voltage and current necessary for the motor (if it can handle more, all the better).

-Dave
Old 07-19-2008, 06:55 PM
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Default RE: ESC's & LiPo's

Ok, so I guess the million dollar question is: does anyone know how much the 300HDX 4200kv motor draws?
Old 07-19-2008, 07:35 PM
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Default RE: ESC's & LiPo's

It depends on what load you put on it: what helicopter you're putting it in, what head speed you'll be running, and how you plan to fly it. You need to give more info than just what the battery or motor is.
Old 07-19-2008, 11:04 PM
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Default RE: ESC's & LiPo's


ORIGINAL: dragus359

Ok, so I guess the million dollar question is: does anyone know how much the 300HDX 4200kv motor draws?
According to [link=http://store.rcsupersales.net/servlet/-strse-913/4200KV-Brushless-Outrunner-Motor/Detail]this[/link], max current is 23.5A
So and ESC that can handle 30A (or higher), would be a good choice.

But please double check these numbers before you go out and buy something.
Old 07-20-2008, 05:14 PM
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Default RE: ESC's & LiPo's

Ok, thanks. I was afraid I'd have 2 replace my esc. I guess I just have one last question then. Will it damage my motor if I try to run the heli and the esc fries?
Old 07-20-2008, 05:35 PM
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Default RE: ESC's & LiPo's


ORIGINAL: dragus359

Ok, thanks. I was afraid I'd have 2 replace my esc. I guess I just have one last question then. Will it damage my motor if I try to run the heli and the esc fries?
Probably not. It's a lot more common for the motor to die and take the ESC with it than the other way around.
Old 07-20-2008, 09:30 PM
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Default RE: ESC's & LiPo's

Ah ok. Well that's good to hear lol
Old 07-21-2008, 07:11 PM
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Default RE: ESC's & LiPo's

Whatever you choose, when you're setting it up do make a few short flights and monitor the temps pretty carefully. Once you've a few flights under your belt and everything fine you can lengthen them out.

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