I am purchasing a proboat recoil 17 as my first rc boat. A 20c 1300mah battery is included wih the boat. I would like to get a second battery so that i can get more run time. Should i get another 20c 1300mah battery or should i go for a 20c 4000mah battery. Im not sure if that will be ok. I understand that mah is milli amp hour and that more will give greater run times. Also, can i get a 30c or 40c 4000mah battery? Im dont really understand the difference but i would assume that it would lead to extra performance. Thats all for now... thanks.