Manual perko switch, and looking at the Dekas from westmarine or Die Hard Platinum from sears. Length of charge time is not really an issue as I am out for a day at a time only. I have pounded the optimas over the years and now they are giving me issues from a voltage standpoint and being able to hold a charge. I think I will be happy going from a 24 to 31 in group size and pure reserve capacity. Ive seen the 30amp charger on your store and am interested, but at twice the price I just wanted to see if the 20 would work