It has a discharge capability?
Yes it does. You have the option to select this, at any point after
you start the charger, by pressing a small button on the front for
a couple of seconds.
It discharges all four cells simultaneously, then switches over to
charging. The LEDs flash in a "scrolling" fashion during discharge,
and a syncronised flashing when charging. An always on LED
indicates a fully charged (trickle charging) cell. A rapidly
flashing LED indicates a faulty cell.
Bear in mind that discharging is a slow process that can easily
double the whole process cycle time. The best advice is that
predischarging NiMH cells is unnecessary, and will reduce the
number the cell's life cycles. This is because the cells
deteriorate slowly, over time, with repeated charging, and charging
half empty cells (as opposed to discharging first) means that they
spend less time being charged per cycle of use.
NiCd cells, on the other hand, do need to be periodicaly discharged
fully, to minimise the so called "memory effect". NiMH cells
apparently do not suffer this memory effect.