If you need to plane a lot of plank you're doing yourself a favour by using an electric planer. It runs on a cord, which means you always have a steady and constant energy supply.
From ManoMano
Gho 16-82 d Corded 240V Planer Blue, 18.4 cm 1.6m 240v 06015A4070 - Bosch
Travis Perkins
Bosch Gho 16-28D Planer 240V