From: "Russell Duffy" <13brv3@bellsouth.net>
Date: 2005/05/15 Sun AM 10:53:36 EDT
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: How long can you fly on your battery??

I was trying to find some info on the Odyssey batteries, and could only find
data for the PC680.   http://www.odysseybatteries.com/aircraft.htm
Fortunately, for me, that's what I have :-)
 
In the battery world, CX rating seems to mean Capacity when discharged fully
(10.5 V) in X hours.   I found some comments that said excess heat and
resistance reduces the efficiency as the current rises, which explains why
the amp hour rating his higher for a lower current draw.  The only specs
given for the PC680 are:
C1= 12.3 Ah     (12.3 amps for one hour)
C10= 16.0 Ah   (1.6 amps for 10 hours)
 
They also list "reserve capacity", which is a standardized rating for the
amount of time it takes to fully discharge a battery when drawing a 25 amps.
For the PC680, reserve capacity is 25 minutes.  This spec is given for all
the Odyssey batteries, and in fact, the PC625 is slightly higher at 27
minutes.   Based on these figures, I should have 45 minutes of capacity easily, and
will plan to be on the ground somewhere in 20 minutes or less.
 
Cheers,
Rusty