Hi !
It's true should have been more clear (i'll update the game page).
The maximum of electricity is 15 but, you are overcharged starting of 13 (when the electricity HUD starts blinking, and your ship have electric arcs). If you stay for 4 seconds in a overcharge state, you explodes. If you are already near to 15, killing other ennemies can't get you higher than 15.
I'll add a progress bar after the jam.
GGs for your highscore, the better one, except me :)
Thanks for playing