Since the charging of the battery of the solar street lamp system is directly provided by the solar cell, the obtained energy is very unstable, so it is necessary to configure a battery with reasonable capacity and reliable performance to ensure the normal operation of the solar street lamp. In solar lighting systems, maintenance-free lead-acid batteries are usually used. The maintenance-free lead-acid battery is a new type of battery. It is fully sealed, with high discharge rate and stable characteristics. It is easy to install, has a small footprint, and can be installed horizontally and vertically. The life expectancy is generally 5-7 years. The general principle of selecting the battery capacity is to first meet the night lighting requirements, and to store the energy generated by the solar modules during the day, while still meeting the electrical energy required for continuous rainy night lighting. If the battery capacity is too small, it can not meet the needs of night lighting. If the battery capacity is too large, the long-term loss of the battery will shorten the battery life and waste unnecessary investment.
A simple way to determine the relationship between them, that is, the solar cell power must be more than 4 times higher than the load power, the system can work properly. The voltage of the solar street light battery should exceed 20%~30% of the working voltage of the battery to ensure normal charging of the battery. The battery capacity is more than 6 times higher than the daily load of the load. The basic requirements for solar street lamps for the batteries used are:
1. The self-discharge rate is low.
2. Long service life.
3. High charging efficiency.
4. Less maintenance or maintenance free.
5. Wide operating temperature range.
6, the price is low.