Thursday, January 20, 2005, 12:21:54 AM, Andre wrote:
AL> Don, I've had the same experience than yours a few days ago. I had
AL> put pre-used alkaline cells and got into problems not long
AL> afterwards. I tested the voltage of the batteries and they were just
AL> over 1.4. I then remembered that Ni-Mh was working better (longer)
AL> and won't use alkalines again.
AL> What I don't get is why the D works so well with Ni-Mh that are lower
AL> in voltage.
AL> Andre
that's probably because of current spikes, and internal resistance.
The IstD must draw over an amp of current in spikes, like AF, image
processing, etc. Alkalines have so high internal resistance that when
they need to give over an amp of current they simply "shut down",
dropping voltage severely to e.g. 1.1V. The voltage then recupers to
the open circuit value, which is your 1.4V. But that tells nothing
about the amount of power left in the battery, because you would need
to measure the voltage in closed circuit situations. Like inside the
IstD, or with a resistor applied. Rechargables have much lower
internal resistance, thus their voltage doesn't drop nearly at all
with high current draw. At least that's how the RC model guys told me.
Or if you want an analogy, there is an excellent one with beer bottle
and milk bottle ;-)
Good light!
fra
