Charging 4S packs? Seems it would be really slow, unless you have the X4-Eighty.

50 watt chargers aren't very good choices for a 4S or larger pack, one of the most common issues posted here.

I had good luck with this turnigy, they also have one that is only a single port that is cheaper if you're only going to run one class, but as soon as a second class comes into the picture the duo is nice to have

http://www.hobbyking.com/hobbyking/s...ger_800W_.html