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Old Jan 24, 2009, 08:02 PM
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sparkie624's Avatar
Roanoke, VA
Joined Sep 2008
928 Posts
LIPO MAH vs Run Time

Does anyone have a formula for estimating battery life of a lipo? For example, I am looking to take fixed data and calculate run time for a particular battery.

I want to take known values of say a 2000 MAH, say 12.5 Volts and 15 amps and convert that into a straight line run time, and then to beable to plug in values later such as for a bigger battery or lighter or heavier current loads to give me a guest-a-mint run time of say a 2400 MAH battery, or what ever. A good way to view what I want to do is judge by my mood. If I know I just want an easy relaxing 1/2 throttle flight, I plug in the approx values, and at the same time if I want to run full power for the full flight (Aerobatics, 3D, Hanging on the Prop, or what ever), then I plug in the higher current values.

I hope I am not trying to make something complicated that is simple, but it seems like it should be simple math that could be plugged into a spreadsheet for quick references.

Thanks in advance for any assistance on this.

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Old Jan 24, 2009, 08:18 PM
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everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,850 Posts
a 2000 MAH, say 12.5 Volts and 15 amps and convert that into a straight line run time,
2000 mAh (2AH)X60/15= 8

17oo mAh (1.7AH)X60/15=6.8min.
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Old Jan 24, 2009, 08:31 PM
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Chicago 'burbs
Joined May 2006
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When I fly an electric RC plane, it is easy to notice that at some point, full throttle is somewhat less than full. At that point I land.

So occasionally pull the nose up with full throttle. You will see that it has lost some "oomph". Now land.
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Old Jan 24, 2009, 08:36 PM
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Prof100's Avatar
Canton, Michigan USA
Joined Jul 2007
16,712 Posts
You have to know the amp draw for a flight (on average). Below is a table that takes the pack to cutoff (not advised, shoot for 20% "LEFT IN THE THANK"). Just looks up the size of battery you are using and the average amp draw to determine run time.

It's an Excel file that if you would like it just send me a personal email and I will send you the file.

Hope this helps.

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Last edited by Prof100; Jan 25, 2009 at 12:04 PM.
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