or if you are like me and always end up with different sizes of battery pack you can try making your own charger.
to charge a battery you want to hook it up to a power supply, +ive to +ive and -ive to -ive and monitor the current flowing into the battery with a multimeter (set to read Amps).
now, before everyone goes and toasts their batteries note the following:
this method will work for NiCad and NiHH but DO NOT use it for Lithium Polymer batteries without first reading up on their complicated charging scheme.
so, on to charging NiCad and NiHH batteries,
you want to first look at the mAH (milli Amp Hour) rating of your battery pack.
let's use jah1282's 9.6V 1400mah as an example.
to charge this pack you would want to connect a power supply which is a few Volts higher than the battery pack. eg a 12V supply.
connect the positive terminal on the power supply to the positive terminal on the battery.
now connect the negative terminal on the power supply to one lead on your multimeter and the other lead to the negative terminal on the battery.
make less current flow into the battery by putting a resistor in series with the multimeter.
have a look how much current is flowing into the battery using your multimeter.
for example with jah1282's1400mAH means the battery can deliver 1400mA for one hour.
to recharge it you want to deliver the same power back into it (plus 20 - 40% for the inefficiency of the whole system)
so with jah1282's 1400mAH battery, 140mA were going into it you would charge it for a bit over 10 hours.
if 280mA were going into it you would charge it for a bit over 5 hours.
you could probably charge it in an hour with 1400mA but you would want to be carefull that the batteries were not over heating and that you stopped within an hour.
generally speaking, the slower you charge your battery, the better life expectancy it will have.
ok, it's not quite that simple.
i suggested using a resister in series to limit the current flow.
the problem is, as the battery charges and it's voltage gets closer to the voltage of the charger you are using, less current will flow.
using the method i described you would have to manually change the value of the resister several times during charging.
use a LM317 voltage regulator as described here: http://www.dprg.org/projects/1999-05a/
the LM317 keeps the output from the charger circuit a set voltage above the battery so the same amount of current always flows.
it's a really simple circuit to set up.
so, although it's possible to fast charge packs like this, without designing some sort of thermal shut out i'd recommend keeping to trickle charging. (ie, slow, all day charging.)
aim for about 14 hours at 0.1 x the mAH rating of the battery for NiCads.
NiHH on the other hand can be trickle charged almost indefinitely with very little damage.
i have a robot that lives in it's charging cradle 90% of the time.
it is constantly charging at about 0.08 x the mAH rating of it's battery and i haven't seen any real degradation of the cells for over a year.