Board Thread:Bloons Wiki and BTD News/@comment-5056929-20130809071543/@comment-3153244-20130812062201

Btd456Creeper wrote: Can you upgrade your towers? (Using energy) Yes - towers are upgraded using only a little energy, regardless of success or failure. The more energy you have, the higher the chance. Different upgrades also have different chances. Successfully upgrading also gives you a small reward ;)