BlueFire PWM 30A Digital Solar Charge Controller Regulator 12V 24V with USB/DC Charger Port High charging efficiency, tandem PWM charging way, longer battery life Short circuit protection and Protect from the lighting strike. Reserve discharging protection and Reserve-polarity protection. Under-voltage protection. Overcharging protection. Over-load protection. 12/24V self-adaptive, USB 5.0V mobile phone charging, and dual-way DC12/24V output. NOTE: If the battery is 12V, then the output is DC 12V. If the battery is 24V, then the output is DC24V.