Tl;dr: Same problem, did some debugging, waiting for Forge to update.
My server is running the regular tech/psudo-tech mod set(IC2, BC, EE, RP2, Forestry, EC), and I just encountered the same problem with the batbox, works fine in SSP, but crashes the client that tried to view the GUI for the batbox.
EDIT1: Update! I took a look at the server output and it seems that the server thinks the batbox is an iron furnace?
EDIT2: It also doesn't accept power from any side, tested by wiring a fully backed up generator to every side at once -1 six times(every side open once while all others were wired.
EDIT3: Just had to rewire the first bit of my system, seems like it was remembering the "batbox" in the place i put it and the wire I put there after removing it wasn't recognized as a passable block, dismantled the whole thing, rebuilt, still nothing. Then I looked at the generator that I had removed just prior and replaced, and not having put any coal in it this time, it remembered its charge level from before. So I broke everything again, logged out, back in, replaced the generator, and it was empty again, rewired a second time, and now my macerator gets power finally.
EDIT4: Ok, looks like If I do the reload thing, the batbox works fine, just remembered that I had an iron furnace in the original spot for the batbox its all working now, you just have to be careful to never replace anything unless you unload the chunk and reload before placing blocks. Time to wait for that Forge update.