So what does it matter if a charger is 50w or 200w? What difference does that make?
It depends on your battery mAh and voltage, and how fast you want to charge them. Here are some examples
Watts needed = Volts x Amps
For a 3s 2200mAh battery, charging at a 1C rate (2200mA which equals 2.2A), you would need to calculate as follows:
3s = 11.1V 1C rate 11.1V x 2.2A = 24.42 Watts
3s = 11.1V 2C rate 11.1V x 4.4A = 48.84 Watts
Minimum 50Watt output charger required for these.
If you wanted to use a Hyperion G3 or similar battery that is capable of 5C charge rates
3s = 11.1V 5C rate 11.1V x 11A = 122.1 Watts
50 Watt output charger won't work for this.
If you were charging 2 2200mAh batteries simultaneously, in parallel, at a 2C rate:
you would need 2.2A (for 1C) x 2 (for 2C rate) x 2 (2 batteries in parallel) = 8.8A
11.1V x 8.8A = 97.68 Watts
you would need at least a 100Watt output charger or greater for this to work.