Please bear with me, did not build my plane and not an electrical genius. My EMS is reading my battery voltage at 12.5, however bat the battery and main buss it's 13.5. chased it down to a 1 volt drop when it goes through a square diode between the main and essential buss? There are 2 wires from the main buss to 2 prongs on this diode and a single wire going to the essential buss leaving 1 prong empty, does this sound right?