proper resting voltage for 24v batt bank?

good day all,i have a mastervolt battery and charging system on the sailboat i am running.12 2v batts ,mastervolt charging controller that commands charging rates from both gens and main eng and/or shore power.sitting at the dock for awhile ,batts topped up what should be ideal resting voltage?i think the way it is now(27.4v) may be abit high.however when i shut off the charger the real resting voltage,start of a discharge cycle is 25.8v,i want to keep the banks fully charged so as to use all available amphours available.i have steering solinoids energized when autopilot is off that are hot to the touch and i have found a burned out coil.thats why i am asking.
so my questions,should i lower the float charge level by the charge controller? should i try to find 28v coils instead?not seeing any other problems but dont want to shorten the life of batts or make more trouble for myself.
thanks for any info.
cw