> With physics like that Ed is not allowed in my capsule. ;-)
> like a damped exponential decay curve from a constant voltage like
> this:
Okay, this is not so bad but there is some little details to be corrected:
> - 1.5V
> -
> -
> --
> ---
> -----------
> --------------- something like 1.2 (at least
with NiMH but similar with alkaline)
> ---
> --
> -
> -
> -
> ---- 0V
The catch is that at the discharge of any battery or accu the voltage drops
quickly goes then into a range of less voltage drop over about 80% of the
discharge time and will finally decrease rapidly if the voltage decreased
below 1V or so.
As the curve was drawn previously its gradients were concave and finally
convex. But it is the other way round: at first convex then concave. I must
have a self recorded voltage drop of a NiMH accu pack, but where...
This is exactly where BatteryLog should jump in: An application which
records the NiMH voltage if the Newton is on and finally generates something
like the above curve. By comparison of the curves one could estimate or even
calculate (by determination of the area under the curve) the capacity of the
Newton accu or battery.
> Most devices (torches excepted) will be designed to operate only at
> or near the top of the curve.
There are a few examples which are designed to operate over the whole range.
They can either accept low driving voltages (3.3V low power CMOS) or the
power supply uses a charge pump technology to get e.g. 3.3V out of two AAA
cells with drive V<3V. Beside charge pump devices there are dozens of DC to
DC converters on the market for many voltage and power combinations.
Marco
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