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C rating

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Old 01-09-2013, 03:28 PM
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iflircaircraft
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Default C rating

Ok, I got my first electric plane. A chipmunk EP.
I ordered a rimfire 400 brushless motor, a 20A ESC,and a 3S 1300mAh 30C lipo. My question is what is the C rating? Is it the Disharge rate? How does it affect the flight time? Would a 20C give a longer or shorter flight?

Tom
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Old 01-09-2013, 03:37 PM
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Default RE: C rating

C stands for capacity and the number is a multiplier and in this case it is describing the discharge rating (probably constant current MAX)

Theoretically the cell can be discharged at 30 x 1.3 ah = 39 amps and this would equate to the cell being drained in 2 minutes. Your chipmunk won;t use it up that fast so a 20C or a 30C is just fine. The 30C having just a slight power advantage due to it carrying a higher voltage than the 20C. It won't affect flight time any.
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Old 01-09-2013, 03:47 PM
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Default RE: C rating

ok, so I can use a 11.1V 3S 1300mAh 30C lipo or a 11.1V 3S 1300mAh 20C Lipo and get the same flight time? Electric can be so confusing.
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Old 01-09-2013, 03:52 PM
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Default RE: C rating

Yes, it is the capacity that will determine the flight time. Use a 3sx1500 for longer flight.
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Old 01-10-2013, 07:02 AM
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Default RE: C rating

Really its the internal resistance of the pack.

The higher the C rating the more current can be pulled from the pack without damage. The lower the resistance the less heat that will be created during high current drain, hence, less chance of damage.

The downside is the higher c rated packs usually weigh a little more and cost more.


Something to keep in mind, manufacturers C ratings are often, shall we say, optimistic. Some mfg's are more like fantasy. So keep a saftey margin.
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Old 01-10-2013, 08:49 PM
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ORIGINAL: iflircaircraft

ok, so I can use a 11.1V 3S 1300mAh 30C lipo or a 11.1V 3S 1300mAh 20C Lipo and get the same flight time? Electric can be so confusing.
Tom
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