The so-called 4.8 V. wall warts will top out a 4 cell batt. at around 5.5-5.8 volts, meaning they top out somewhere around 6V. Marketing people have methods to satisfy folks to purchase stuff. If your batt. was only charged to 4.8 V, the rated voltage, you would be out of juice very quickly. I have checked some JR chargers at 17 Volt output for the Tmtr side. Labels are there to satisfy the buyer. [sm=confused.gif]
OTOH there is not adequate Voltage to top off a 6V rated pack. Remember your 5 cell battery goes down faster than a 4 cell because of the pressure pushing more ma through the servos.

My suggestion is to visit radio Shack and check their small batt. chargers. I have a bunch of chargers and some were absolute steals. I hardly ever use them but sometimes they come in handy. I have two that charge NMIH and NICADS from 2.4 to 12V packs. I can set the voltage, and each has adapters for either JR or other Transmitters and charge a transmitter or in-flight batteries. They are different but they do the job. On one sale I got 8 NMIH cells, an 800 mah set and a 1500 mah set plus a charger for LESS THAN $1. You just have to go see.

I have adapted several chargers by soldering leads to the tin contacts and thus use them just like any charger.

I also have a couple regular chargers to cycle Nicad/NMIH batteries.