Built an EDF composite ARF Rookie gen 1 plane. Has a 120 mm ramtec fan, big screamer motor, 200 amp jetti esc, plane was maiden on sunday. Flew for 3-3.5 min but we would like to extend the flight time to 5-6 min. Would it be best to add more cells such as going up to 15-16 cells or go with more mah batteries? the current batteries use for first flight were 5500 in 12s configuration. Any advice or ideas would be greatly appreciated. Thank you in advance.