A while ago, I changed the Hydra design to use a primary 5 volt supply and a boost converter on the logic board to supply the pilot generator. I also made this change on OpenEVSE II, and at the time, the shared HV board dictated that design here.

What was missed in that design choice was the fact that the Hydra only supports using contactors. There's no provision for DC relays because an L1 Hydra essentially makes no sense (you'd just plug two L1 EVSEs into two different 120V circuits). Asking a boost converter to make enough 12 VDC for both the pilot generator and to trigger a relay is on the border of asking too much, whereas a buck converter to make 5 volts for the logic system and the Pi is not a big deal at all.

So since the OpenEVSE II HV boards are going to switch over to a 12 volt primary supply, that means swapping out the boost converter for a buck converter, and it has to be beefy enough to run a Pi as well.