No one pack at a time, I get about 6 mins out of these packs maybe 7 but that's about it, But I'm still learning after a 2 month departure from Heli's So duration isn't a key factor right now proper technique is priority which I've got to follow more closely and as a key advisor Mini Boy said to me time and again "take your time and do it right". The other thing you'll notice is the battery is slung underneath, most Corona Flyers are using Voyager E landing gear to mount the battery under the Corona, helps balancing and frees up space for gear ie: RX etc.