If you do the Old mission in Hagios, you get one every single time without using the code breakers. You choose Hard mode, run it on private and go to the point where you get the kuiper circles, dont do the circles just clear the mobs until time runs out, an you will get every single run 1 energy residue and 50 Heat plasma battery, it will take you around 4 minutes "depending on wich Descendant you use, Bunny is the best choice or Valby", no need for code breakers, i admit its less yield than the vaults but you also get the Heat batterys for the Activators. Edit: its now dropping 1 every 2 runs, but you get 50000 gold, 3000 kuiper, 50 to 54 Heat plasma battery, its still a win for me.
Top shelf advise dude.. you just saved me a crap load of time.. I wish you and your wife/partner 1000 camels :) .... sell them in Egypt as it's very hard to sell them in England