Zamp Solar's 15 Amp 5 Stage PWM Waterproof/Weatherproof Digital Solar Charge Controller helps keep your batteries at their fullest charge without over heating and damage to you battery bank. A high quality charge controller is an essential component to your solar system.
Typical RV batteries are replaced between 2 and 3 years depending on how many times they are depleted, how far depleted and what kind of charger was used to recharge them. Using a PWM solar charge controller with solar can extend your battery life up to 3 times. It's not uncommon for batteries on PWM controlled solar charging to last for 9 to 10 years plus.
PWM is technology that properly regulates the voltage of the battery for best battery health and longevity. Solar charge controller with PWM technology communicate with the battery and solar panels to deliver the proper power the battery needs without overcharging or overheating.
Take care of batteries and they will take care of you.