eFoil DC motor used as a generator to charge battery


Maybe there’s a better way to use the wave energy like producing our own electricity. It could allow to decrease the battery case volume and therefore the board price …
Inspired from: Using a brushless motor for a generator

In addition to waves or a good pumping technique, what else do we need ?

  • Propeller: what is the optimum pitch for a propeller to be reversible ? 1 = 45 degrees ?
  • ESC: as it shouldn’t allow reverse currents, a diode should be set on each of the 3 phases to forbid reverse current in generator mode.
  • Bridge rectifier: the 3-phase AC will need to be rectified into a DC output
  • Motor: can the reverse voltage/current behaviour of a DC motor (generator mode) be deduced from the same motor (V,I,rpm) characteristics used in direct mode? Mounting it to an equivalent motor in direct mode (a drill ?) controlled by the efoil ESC would be a good mean to get that characteristics though …

Negative points to expect:

  • 10 to 20% efficiency loss
  • is direct drive compulsory or a gear will allow to max out the low speed ?
  • some sudden drag when going down the wave which could mean “loosing” it