Looking at picking up a 2 channel lipo charger, and am wondering how to calculate approximate charging times on a dead battery. Looking to reduce downtime during practice sessions at the track.

I have a few Lectron 2S 4600mAh 100C (5C charge rate) batteries. What would the effective time difference using either the Hitec X2 AC Plus Dual Port AC/DC Multi-Charger (6S/6A/100W) or the ProTek RC Prodigy 625 DUO Touch AC?