🚀 go-pugleaf

I am having difficulty in getting a full charge into the battery
which comes with my Zenith Supersport 286(20 mb hard disc).  On
three occasions in a row it has run out of juice after between 70
and 80 minutes use as a dumb terminal hooked up to the Vax I am now
on, which involves no hard disc use after initial connection.

The 286 is one year old; the battery has been drained and recharged
perhaps a dozen times. Previous to these incidents, it has lasted for
more than three hours of word processing, with lots of disc activity.
A program called "Battery Watch" version 1:00(C) has been installed on the
hard disc. It has a "Deep Discharge" feature which they claim will
"discharge the battery as deeply as possible"..."in order to remove
a memory-effect problem in a NiCad battery."  I do not have the Battery
Watch manual with me.  The 286 owner's manual does not tell you exactly
how to recharge the battery.

When the 286 is on battery power, and the red power light blinks and
the beeper sounds, I have tried to completely drain the battery in two
different ways:
(a)by running the machine until the screen goes blank and the power
light goes out; and
(b)by using the Battery Watch deep discharge feature to do the same thing.

I have then attempted to recharge the battery (disconnected from the
computer itself) by plugging in the power supply unit (model 150-308)
which comes with the 286, and then plugging that into the mains overnight
(16 hours the last time).  This has worked in the past, but seems to work
no longer.

Can any Zenith or laptop mavens out there tell me:
(a)What have I been doing wrong?
(b)Can this battery be restored to taking a full charge, and if so, how?
(c)Is the battery harmed by leaving it on the 286 and hooking up to mains
   power through it?
(d)Just what is meant by "memory-effect" problems with nicads? And
(e)Is there a Zenith dealer in Perth?

Thanks in advance for the rescue.