I use the Hobico "Multi Charger" (http://www3.towerhobbies.com/cgi-bin...&I=LXL331&P=FR)for my 4.8 and 6.0 volt airborn packs. I also use it to charge my transmitter packs and even my 12 volt field box battery when I want too..

The simple explanation, just following the instructions, you match up your charging requirement based on the capacity (milliamps) of the pack and charge at approximately 0.1C for 14 hours..

I understand that it works for the different voltages because the voltage load is a lot less sensitive than the charge rate.. So, you can charge a 4.8 volt pack, your 6.0 volt pack and your 9.6 volt Transmitter all on the same charger by just setting the correct charge rate..

It's a great price, works great and I really like mine...

Disclaimer, I also check all my packs with the Futaba battery checker(http://www3.towerhobbies.com/cgi-bin...&I=LXEYM6&P=ML) to make sure this thing is doing it's job...