I have disabled 7 of these and only ever got 2 drannik power cores? Im thinking that it's not worth wasting 100's of energy for a trap and watching everyone else to get the drannik power cores?

hehe! get use to it... when you will get all of them you will get more and more...

The chance starts at 0.00000001% when you got none and is close to 100% when you got all four. It's the same with the Xiloy cores as well.

Source :

Experience.

Never heard about the drop rate increasing with each power core you get. I always assumed that akkieren drops mostly swarm traps and okkilor drops mostly power cores.

ive helped kill 4. Got 1 core, 3 traps

keep pushing through them, youll get them eventually. and i believe the higher level one okkiler (i think) has a higher drop rate on power cores.