On the latest version it appears that coercion derivers aren't keeping track of the energy stored correctly.
I'm using them to charge a fortron capacitor, and they do that until the charge within them runs out, despite having a power source. Right-clicking the derivers work, and in the energy stored UI you can see it jumping from 0 up to full, but then it stops working once the energy's drained.
https://gyazo.com/b5100294bdcd53ff15b9e3a5cfbc89b3

It's a shame the modes on the fortron capacitors were removed too, because it then empties out the capacitor trying to re-fill the derivers.