so lets do some wattage calculations
Battery Voltage range for 18650 is 4.2 - 3.2
3 batteries in series : 3 x 4.2 = 12.6V & 3 x 3.2 = 9.6V
Assuming you wanna top out at 200W you will need : 200W / 12.6V = 15.87A | 200W / 9.6V = 20.8A
So LG HG2 at 20A is still within the limit.
Battery Voltage range for 18650 is 4.2 - 3.2
3 batteries in series : 3 x 4.2 = 12.6V & 3 x 3.2 = 9.6V
Assuming you wanna top out at 200W you will need : 200W / 12.6V = 15.87A | 200W / 9.6V = 20.8A
So LG HG2 at 20A is still within the limit.