Can't he learn to charge it while fighting? Like when Goku charges his kamehameha while moving around.
Could he split in two - 75% and 25%? One Piccolo stays at home by the waterfall and charges a makankosappo all his life. The other Piccolo plays checkers with Gohan (Gohan wants to play chess, but Piccolo left 1/4 of his brain power at home). Then when they fight Beerus, the 25% uses instant transmission and appears behind Beerus and fires the makankosappo he's been building for 20 years.