Yep that is the major issue with biplane electric conversions. A club member managed to do an electric conversion on a 100cc Beast but that plane has a huge canopy hatch that opens up much like a monoplane, he is able to get his four 6S 5000's in there, yes that's right 12S 10,000 mah, two in parallel to create the 10,000 size and then series connect those. A whole lotta charging for one flight!