We all know that the moon somehow triggers the effect to cause a transformation. On that note, what is it about the moon? Is it the light? 

If that's the case will a total lunar eclipse mess up the transformation since he (Lupin) is no longer receiving the correct dosage of energy as the moon goes through all its phases very fast? Totality lasts about 20 minutes when the moon goes to a blood red color (which is due to atmosphere saturation).