Hi,

I have the impression that if I use a charger/cycler for measuring the capacity of a baterry pack the value that I will get is not the "capacity" I would have for actually flying. I mean, after the voltage drops under a certain level the remaining capacity is useless because the pack is actually not able to drive the on-board electronics and servos. This means that as for measuring the "flying" capacity of a pack I should not fully discharge, but instead I should discharge only until the voltage drops to a certain level.

If I look at my hobbico ESV, and I assume the nominal voltage of an AA NiCd cell (1.2v) then I always land very near the scaring red stripes. If everything is true about this "flying capacity" (as defined above) should I discharge down to 1.2v/cell as for measuring it?

thanks,

The battery mfgs tend to use 1.0V per cell, with C/5 Load, at room temperature as the cutoff voltage. You can measure a more appropriate "flying capacity" by using a cutoff voltage that is as low as you dare fly with. If you fly in cold weather, then perform the measurement at the intended environmental temp. For extra comfort, the load could relate to your system's current draw under your intended flying style. In warm climates, 1.18V/cell is a good place to end the day.

I think you will find 10% to 30% remaining capacity if you do this (safety margin). The difference in flight times is nearly nill (you are at the sharp end of the discharge knee).

BTW, Most discharger/cyclers use either 1.0V or 1.05V per cell as the cutoff; the user manual should tell the full story. The load is usually predefined for you and is not always at C/5.

I HAVE A GAS GAGE IN MY CAR THAT HAS A RED LINE THAT INDICATES EMPTY. WHEN THE NEEDLE REACHES THAT LINE I GET OUT AND PUSH A STICK INTO THE TANK AND I NOTICE THERE IS STILL GAS LEFT IN THE CAR. THIS BOTHERS ME NO END AS I DONT KNOW WHETHER I SHOULD DRAIN THE TANK SO THAT I KNOW THE REAL CAPACITY OR SHOULD I FILL UP WHEN THE GAGE SAYS EMPTY ?