Small outdoor photovoltaic energy storage systems are widely equipped with 12V lead-acid batteries as core energy storage and backup components, commonly used for courtyard photovoltaic lights, outdoor monitors and small photovoltaic power supply equipment. Photovoltaic panels convert solar energy into electric energy to charge the batteries in the daytime, and the batteries automatically discharge to supply power at night or on rainy and cloudy days. Compared with other batteries, 12V lead-acid batteries are durable, overcharge-resistant and adaptable to complex outdoor temperature changes. The independent power supply system is very suitable for daily power supply and emergency backup of small outdoor equipment in courtyards without municipal power.