I'm with Gray Beard. I've run 5 cell packs since the late '80s. Remember, if room is at a premium, then you can use 2 500 or 600 mah packs and have 1000mah, 1200mah at your disposal. Just plug the second battery and switch into any unused channel. This also, divides the current load which will allow lower amp draw per battery, giving more useable power in your system.

BTW, just my opinion. But I would not run the retracts from my receiver battery. If the retracts drain the battery, the only thing left is a crash. JMO.