Matt wrote:
   On a brand new, fully charged battery, 15Ah at 5A is 3 hours of run
   time.  Add a difficult start, some idle time on the ground, and some
   other flight loads like radios and lights, and you may be lucky to get
   1.5hours of run time from the battery.  That's not enough in my book,
   and certainly won't allow you to use up all of your fuel.
   ---------
   Actually if you mean a 15A-Hr Battery, the above statement is
   incorrect.
   Battery amp-hours are usually rated at the 20 hour discharge rate. At
   higher draws, the capacity goes down significantly.

   Bill Schertz
   KIS Cruiser # 4045

   --------------------------------------------------------------

   Let me do the math here Bill and correct me if I am wrong.
   15A-Hr / 20 hours is .75 amp draw.

   Here are a few curves. It also appears there are significant temperature
   effects on the discharge rate.

   http://www.batteryuniversity.com/partone-16a.htm

   Paul Lamar ...No rotor no motor.




You are right Bill, though I was thinking of derating a 20Ah battery to
15Ah of capacity when discharged at 5A rate...


Matt-



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