[JFP in PA]

By far, one of the best out there are the Ctek models. They make the units for Porsche, which you can buy much cheaper online as Ctek. All Ctek units have an auto de-sulfating step in their programming, which is critical to extending battery life. Many cheaper maintainers do not have this critical mode, so you do "get what you pay for" with a quality unit. Some of their models include the ability to recondition a severely discharged battery, and a constant power supply to hold electronic settings while disconnecting the battery. Nice units with a lot of features, and at a fair price.