On Sun, Nov 1, 2009 at 2:51 AM, Peter Loron <peterl@standingwave.org> wrote:
> You also need to take into account the discharge curve of the battery
> type in question, as well as the consumption of the device you're
> trying to power. Yes, rechargeables have a lower total mAH capacity
> that alkalines, etc, but their voltage/time curve tends to be much
> flatter, especially for NiMH cells. If the thing you're trying to run
> does well in the voltage range that NiMH cells tend to fall in as they
> are discharging, then you can actually get *more* runtime from them
> than alkaline cells.
>

Hi Pete,

I could see that this could theoretically be true, but I doubt it is
very commonly true of battery powered devices. The end-point voltage
of NiMH is about 0.9V. If you have a device which can work properly
from 1.5V down to 0.9V, then it would use the entire range of an
alkaline battery and you should still get more runtime out of the
alkaline than the NiMH. I think that the only way that an NiMH could
deliver a longer runtime would be if the device were only able to
operate below 1.3V or if it were much more efficient from 1.3V to 0.9V
than it is from 1.5V to 1.3V.

Sean
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