sterling Charger

[gbendaly]

hello there,
does any one have a sterling "smart" charger for the batteries in his boat??
if so do you keep hearing a humming noise while plugged to shore power??
more over does this humming continues (around 50mn)long after you have unplugged the shore line ?? it is really annoying and quite loud !
the batteries I have are lead acid sealed maintenance free 75 amps/h and and they always topped of ( 14.5 to 15+ volts ) which is excessive !! but the smart charger is supposed to regulate the voltage shouldn't it ? well If any one can help me with this issue please advise.