Solar Battery Circuit Of Various Batteries

Solar cells are the converters that convert light energy into electrical energy, and do not store electrical energy, so the lifePo4 battery is essential when there is no light or power to the load This chapter describes the lifePo4 batteries that are commonly used in solar power generation systems.

The battery used in solar power generation system, commonly known as the secondary battery, the use of rechargeable batteries, photovoltaic power generation system in the battery, as a floating charge of the work, no charge must be very little discharge.In general, The battery for electronic products is a silver oxide battery or a slow discharge type nickel-cadmium battery, and a low-discharge type lead-acid battery is used for the electric power. For such a secondary battery, the following properties are generally required:

The use of solar cells in the environment have long-term stability of the charge and discharge characteristics,
Since the variation range of the light incident on the solar cell is large, the charging efficiency is high in a wide range of the charging current.

• Overcharge resistance, over discharge.
• In the use of self-discharge environment is small.
• Long cycle life.
• No leakage, no gas emission, or less leakage, less gas emission.
• High energy density.
• low cost

The existing battery and its characteristics, can basically meet the above requirements, for electronic products often nickel-cadmium batteries and silver oxide batteries; for electricity often lifePo4 batteries and nickel-cadmium batteries.

The so-called floating charging system, refers to the power supply (such as solar cells> connected with the battery well, when the power input power, in addition to providing load turtle power, but also a small current on the battery charge, and when the power is no power input, the battery Discharge to the load power supply.

Nickel-cadmium battery anode active material is nickel oxide, cathode active substances is cadmium, and electrolyte with potassium hydroxide, lifePO4 battery pack such open type and closed type two, in recent years, mostly in closed type.

Ni-Cd batteries have the following advantages:

• Resistance to overcharge, over discharge ability, generally do not install a stable charging circuit can also be used
• Long life, charge and discharge cycles of several hundred times or more, the shallow depth of discharge light load, the charge and discharge cycle of up to 1000 times,
• The internal resistance is small, there may be high-speed discharge, and the discharge voltage fluctuations
• Can be used in a wide temperature range,
• And the size of the same battery, the operating voltage is also close, so there is interchangeability.

The battery has the following disadvantages:

• Self-discharge larger
• Capacity volume is relatively small

With respect to the charging of a Ni-Cd battery for solar powered portable generator, charging is carried out at a rate of less than 1/10 of the battery capacity C, that is, less than 0.10C, in a special case, and the newly charged fast-charge type can be charged with a current of less than 0.33C. Usually the root of the charge current to consider the output of solar cells to 0.10C of current to charge, to reach full charge to be more than 10h.Therefore, is the largest day of the sunshine time is very short, only 3-4h, Therefore, the area of solar cells with electronic products should be large, sometimes the maximum sunshine when the charge current to about 0.3C to use, but the priority in battery life, the current limiting resistor can also be connected in series to the charging circuit , So that the input current is less than 0.1C.

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