I use a Sirus Charge Pro, it is only a charger so you will need something to discharge you pack if you what to cycle your batteries (a good idea). The Sirus charger is a 12VDC charger that can be used with your field batt. or plugged into the lighter of your car.

I charge one plane and transmitter on the way to the field and the other at the field. This charger is fully automatic and has corrected batteries that other charger/cycler said was no good.

I think they are about $110 now and worth every bit of that.