ORIGINAL: gaRCfield
I use two 450mah packs with two independent PLR5e regulators. I plug/unplug my Rx batteries before/after each flight when I plug in my power packs.
This setup came as a recommendation from Ed at Tech-Aero for the lightest possible setup (using 2 rx batteries).
I don't think I use half the capacity of my Rx batteries in a weekend of flying.
Idon't really recommend this 5S / 2S configuration, but I have explained to some how it can be done. The output from the regulators is clean enough, no big concerns about AC components and what not, but if you don't wire this exactly right, you can smoke your receiver, regulators, wiring etc. If you know exactly what you're doing, fine. Otherwise, use a 2nd little LiPo please as gaRCfield is doing.