On Thu, 25 Jan 2007, J. C. O'Connell wrote:
> If I am not mistake, NIMH batteries all have
> appox the same internal resistance and its very
> low compared to Nicad for example. specifically
> what kind of load are you draining them at and what
> is the output voltage of the cells under that load?
> Once a nimh drops below the rated voltage of 1.2 VDC the
> charge is nearly gone regardless of load...
> jco
>
I'm using a LaCrosse BC-900 charger. It will cycle individual
cells under a constant current charger or discharge, while integrating the
total charge/discharge mAH capacity. As such, it's a constant current
charge/load... not a constant resistance.
The cells I'm referring to are Powerex 2150 mAH (IIRC), and I did
the cycle at 700mA charge, 350mA discharge.... That's roughly C/8
discharge rate, and I obtained approx 2000mAH before dipping below 1.1V.
On these cells, they're not dead at that rate until they get between 1.0
and 1.1V... on the Energizer cells it's much closer to the 1.2V you
specifiy.
Bottom line: Cheap cells illustrate a higher internal impedance
than higher quality cells... even at the same mAH rating. That means they
don't last as long before the camera thinks they're dead.
-Cory
--
*************************************************************************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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