"ASAAR" wrote in message
...
On Tue, 27 Sep 2005 16:01:06 +0200, imbsysop wrote:

You're way ahead of me on this and I'm afraid I don't know what -dV/dt
means. Is that something related or similar to the "FLEX negative pulse"
charging that Maha advertises (which is also Greek to me)?

whoops .. yes it is probably the same thing the Maha guys mean ..

what is refered to is that, at "full" charge NIMH's and NiCd's exhibit
a short steep voltage raise followed rather quickly by a sudden small
voltage drop. This is commonly refered to as a -dV/dt aka a negative
voltage increase per time .. modern chargers detect this dip and act
accordingly, mostly switching to so called "trickle" charging ..

I don't think so. dV/dt just refers to monitoring the changing
slope of voltage vs. time. That could be done with any type of
charging circuit, even an extremely simple one based on little more
than a capacitor and a diode, and maybe a current limiting resistor.
Charging using pulses of current (used by my old, but poorly
designed RayOVac renewable alkaline/NiCad charger) is supposed to be
a better method. Possibly more efficient. But adding negative
pulses (slightly discharging between positive charging pulses)
supposedly leaves the chemical structure of the battery in a better
state. i.e., the batteries retain their fullest capacity for a
greater number of charge cycles. Whether that's completely true or
an oversimplification I can't say, as I don't recall reading it in a
white paper or fact sheet from a battery manufacturer's website.

Dang, this is an interesting discussion. (Defined as "any discussion that
leaves me knowing more coming out than I did going in.")

N.