For instance look up
iMax B6 Lipo Polymer NiMH Nicd Digital Balance Battery Charger
On the auction site or go to hobbyking.com and look at chargers ratings. Many other sites, but you can get a charger that uses 12 volt input for $20-30 shipped and a combo 12 volt supply and charger for $25-35. They will be 50 watt type chargers but will do a pack at 1C in an hour unless you have high amp packs for electric flight.
Get one that does lipo lion and life because life is arguably he best flight pack to use.