E-Flight Power Sources Ask questions or read about power sources as they specifically relate to e-flight including Lithium-ion, Li-Poly, Nimh and Nicad battery packs.

Flight times

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Old 08-18-2012, 07:44 PM
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andrewskj
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Default Flight times

If you know the amp draw and the size of battery what is the formula to figure the approx flight time ?
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Old 10-07-2012, 10:28 AM
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Glacier Girl
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Default RE: Flight times

Divide the capacity of the pack by the amp draw.
Multiply that figure by .8
Multiply the figure by 60

Most use the 80% rule
That will give you 80% of the packs capabilities in minutes at full throttle.

Here's an example. 5000 mAh pack, 45 amp draw from motor.
5000 /45000 = .1111111111 or 5/45 = .111111111111 Same difference, just either using milliamps or amps for your figures.
.111111111 x .8= .08888888889
.88888888889 x 60 = 5.333333

So 5.3 minutes at WOT, to use up 80% of the pack. Gives you an approx time, which if you aren't running WOT all the time you can stretch slightly, and even if you do, you know you still have that 20% in reserve for a go around or two if need be.

Also the 80% draw tends to make your packs last longer as they aren't being stressed as bad as running to cut off voltage.

I've got packs going on 7 years now, hundreds of flights, and they still run like day one. I also balance charge em every time I charge em.

Funny I just thought of something. How things change. You can buy a decent 3S2200 pack for under 10 bucks now. When I bought my packs, 3S3700 20C, I paid over $130.00 a piece for em.[X(]
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