Probably no harm done, but the fact that the charger is not quite
rated to 2500 means your batteries may not ever get a full charge.
(Although i would guess it has a little headroom...)  Be patient -
fast charging is not necessarily a good thing.

And when you finally kill off those batteries and want to get a better
set of batteries+charger, I'd suggest you go with hybrids, like the
Sanyo Eneloop.  Better technology - they don't slowly self discharge..

Yep.That's only marketing, so that you buy their own batteries.You may use
any battery brand that you like.

Usually, you can charge'em.Only a dumb charger may overcharge a battery if
you let it too long;any smart charger will switch itself off when it senses
that the battery is full.BTW,IMHO slow (or trickle) charging is much better
for the batteries.I bought mine for 6 euros,bulk price,MW with 4 NImH
batteries, and although its charging timetable states up to 1500 mAh, I
happily use 2000 mAh, and just let it 8 hours more (150 mA constant current
dumb charger)

HTH,

--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr

The 2500 Energizers are actually less so you should be fine.

Your charger will be fine also. It is a smart charger and if the
battery is to large in capacity it should shut down without harming
anything.

If the LED hasn't lit then remove the batteries and check their
voltage. After 4 hours a freshly charged battery should be at
least 1.3 volts if not more. If less it's time to use another charger
because this one refuses to charge these batteries.

 It shouldn't be much of a problem, if any.  If (as I assume) your
1,950 mAh batteries are several years old, they probably have much
less capacity than when they were new, and it wouldn't surprise me
if they now are equivalent to 1,500 mAh or less.  If they are 1,500
and take 3 hours to charge, then they would have taken about 4 hours
to charge when they were at their peak capacity of 1,950 mAh.  Your
new Energizer batteries would then need about 5 hours to fully
charge.  If your Panasonic batteries actually now have less than
1,500 mAh of capacity, then 2,500 NiMH cells would require more than
5 hours to fully charge in the BQ390 charger.  A simple way to tell
if the batteries are being fully charged is to feel them and note
the temperature when the charger shuts off.  For most of the 4 or 5
hours that they're charging, they should only feel warm.  When the
batteries approach full charge, they should get much hotter.  If you
don't notice a significant increase in temperature during the last
15 minutes (approx.) of charging, then the charger is shutting down
prematurely.  As it's already taking more than 4 hours, even if it
shuts down early, the batteries would probably be fairly close to
being fully charged anyway, so there wouldn't be a large benefit to
buying a newer charger, especially since batteries deteriorate with
age and use, so in a couple of months they'll probably have
capacities of 2,400 mAh or less.

 It I had this case to consider, I'd get a newer charger only if I
had some of the newer 2,700 or 2,900 mAh NiMh cells, or if I had
some need for a faster charger.  I actually have a several chargers.
One charges in as little as 30 minutes, but I typically use one of 3
other chargers, which take from 4 to about 8 hours to finish
charging.

 Nope.  No harm done, and as I said above, your old charger is
probably fine unless you'd like to get a faster charger.  If you do
decide to get a new one, try to make sure that it's capable of
charging each cell individually.  Some of the cheaper chargers only
charge NiMH cells in pairs, and while they'll probably work fine
initially, they won't do as good a job as the ones that charge each
cell individually if your batteries aren't new or if all of them
don't have about the same capacity.  It's not too difficult to avoid
wrecking your batteries, and the main way is to charge them before
they go dead.  Some cameras drain the batteries so slowly when
they're not used that batteries can safely remain in them for 6
months or longer.  Other cameras can cause the batteries to go flat
with even as little as a month or two of non-use, and if that
happens, one or two of the NiMH cells in the camera will probably
suffer some damage, ranging from losing a small amount of capacity
to being unable to take a charge.