Moved from Michigan last summer to Hampton Virginia and brought my Hunter 340 with me. In Michigan the batteries were removed during the winter, in Virginia they are typically left in the boat over the winter (it gets down to about 20 deg in January).My #27 AGM's are 4 years old, very tired and need replacement. I understand gel cells are better at low temp than AGM's. Am about ready to flip a coin between the two, can anyone offer any advise?