FYI - I just checked the chargers for the Charge (Am I stuttering?).
The tiny cube travel charger that comes with the phone is a 5.0 VDC / 1.0 A charger.
The Samsung multimedia dock / charger (that has the backup battery) comes with a 5.0 VDC / 0.7 A charger.
So, as crazy as it sounds, the larger dock/charger actually has the slower charging capabilities. This may be to prolong battery life, though.
While LiIon battery packs can be charged quickly, it stresses the battery pack to do so. A slower daily charge will allow for longer overall lifetime for the pack(s).