On Wed, 01 Nov 2006 20:48:54 +1100, Paul wrote:
> It all has to do with the voltage curve. Alkalines start at 1.5 volt but
> quickly drop through 1.2v (which is the nominal voltage of NiMh). NiMh
> stay at 1.2V until flat. You might notice this behaviour with the
> battery indicator on your camera. With Alkalines you take a couple of
> shots and the low battery indicator comes on, but you can take 10 to 20
> more shots. With NiMh the low battery indicator comes on and you are
> lucky to get a few more shots.
Alkalines have a much steeper voltage curve, but they provide
their power while dropping from a bit more than 1.5 volts down to
0.6 volts or lower. That is, they'll continue providing power over
that range, but only to devices that won't power off early. Usually
motors and non-digital electronic devices are the ones that can
operate down to very low voltages. Such devices can quickly kill
rechargeable batteries though. NiMH cells quickly drop to about 1.2
volts, but with continued use will show steadily decreasing voltage
until they reach about 1.0 volts. At that point they're just about
100% depleted and need to be recharged. What you say about NiMH
batteries dying soon after the low battery indicator comes on is
true, but when that happens with alkaline batteries, you might get
far more than another 10 or 20. When that happened with my camera,
it was able to take more than 400 additional shots. There's a trick
involved though, where the shooting conditions before and after the
warning weren't the same. Hint: The flash was involved.
> It is also a risk to take more shots when the indicator comes. The
> last thing you want is for the batteries to go flat during a write to
> the memory card. This may scramble the contents of you card.
> Low battery really means replace or recharge the batteries.
It's a shame that some?/most? cameras aren't smart enough to avoid
that kind of damage. I've seen battery powered MD and mp3 recorders
that flash a "low battery" warning and refuse to record when asked
to do so if the batteries are too low.
>> Stay informed about: Fujifilm FinePix E900 digital camera