The Prostar 15 or Prostar 30 provide higher charging efficiency, increases the battery capacity, reduces water loss, and extends the life of the battery. Prostar PS-15M 12/24 volt 15 amp charge controller w/LCD meter Standard Controller Features: Temperature compensation. High level of lightning protection. Computerized production testing. Ambient temperatures of - 40ºC to +60ºC. Expected 15-year life. Parallel capability for higher current ratings. Easy to use Constant voltage, PWM series charging. Reverse current protection (at night). ISO 9002 manufacturing. High efficiency, low self-consumption. Tropicalization - Epoxy or conformal coating. Five-year warranty. No need to derate - 25% design margin.