Specifications: Size: approx. 13.3 x 7 x 3.5 cm / 5.24 x 2.76 x 1.38 inches (LxWxH). Battery voltage: 12V / 24V (automatic detection). Input charging current: 10A / 20A / 30A, depending on the selected model. The panel's maximum output current should be approximately 25% lower than the controller's maximum input current. For each single 6A 100W panel, use the 10A model. For two 6A panels (total 12A), use the 20A model. If unsure, use the higher current model. For example, if the panel's maximum output current is 9A, use the 20A model instead of the 10A model. Maximum discharge current: 10A. Internal power consumption: <10mA. Overcharge protection: B01 Sealed: 14.4V / 28.8V. B02 Gel: 14.2V / 28.4V. B03 Flood: 14.6V / 29.2V. Overcharge float: 13.7V / 27.4V (default settings, adjustable range 12.7-15V). Over-discharge protection (discharge stop): 10.7V / 21.4V (default settings, adjustable range 9-11.3V). Over-discharge recovery (discharge reconnect): 12.6V / 25.2V (default settings, adjustable range 11.5-13V). USB output: 5V / 2A (max). 12V batteries should be used with solar panels that can produce 18V to 25V. With 12V batteries, the panel's maximum voltage should not exceed 25V. 24V batteries should be used with solar panels that can produce 36V to 50V. With 24V batteries, the panel's maximum voltage should not exceed 50V.