As long as the PSU has greater watts than the total amount your charger needs. So if your charger is Dual channel at 50 watts easch then a PSU that is rated at 120W or more will be fine. You want your power source to be greater in watts than the total amount needed. Kinda sounds confusing. Think of like your batteries, esc and motor combos. You want your batteries to be higher in amps than your esc and you want your esc to handle great amps than your motor.
By doing this your providing overhead and not stressing out your hardware as much. Thats the whole reason for me upgrading my charging case. My PSUs output just over a 1000 watts at 46 amps. My charger can take 1000w upto 36v at 40 amps. I dont have much head room if I go full bore on a charge cycle. I would rather have to much and not need it than have to little and need more.