Hi!
Been in this hobby since 1975...
Charging should be done at home...over night (16-20 hours), Not at the field!!!!!!!
...Seen many new comers that have destroyed their batteries by fast charging. No NiMH cells should be fast charged the first time you charge them...Never! Doing that is sure way of destroying them.

The wall charger that came with the radio is what I recommend to charge your radio batteries (and what I use most of the time my self) All wall chargers supplied with radio systems work with either 4,8V or 6V batteries.
I Charge my Spektrum DX-6i (4,8V) transmitter with one of my JR wall chargers (with the 11v transmitter outlett)
No one uses NICad batteries any more over here in Europe! Are they still available in the US???
NIMH cells are most common and LiFe cells or LiPO are options that work good too.

If you want a fast charger...get one , but use it with discretion!