I have Energy transfer leveled up to full (level 3), but it seems it is not give me full energy after I kill someone. This happened before patch 1.9 and, after the patch, it's the same problem. And the Retriver has been reseted to zero from level 3. Any ideas?

The retriever problem has been around for a while, but they nerfed energy transfer to not give you full energy.

u can get full energy... just make sure ur not using any energy at all when its transferring... using energy during the transfer will interrupt the transfer process which takes about half a second...

eg of using energy while transferring = cloaking or using armor immediately after the kill...or using nanovision