How to test the capacity of lithium-ion battery？

General conventional charging is "two-stage constant current charging", this method neither wastes power nor takes long time to charge, which is beneficial to extend the service life of lithium-ion battery. At the same time, it is much easier to calculate the capacity of lithium-ion battery. Wind power, on the other hand, is different from conventional charging.

The reasonable capacity configuration of lithium-ion battery will directly affect the technical and economic indicators of wind power generation. If the capacity setting is too small, the surplus electricity generated in windy conditions cannot be fully stored. Capacity setting too large will increase investment; in addition, lithium-ion battery may be in a state of long-term charging dissatisfaction, which will affect the efficiency and service life of lithium-ion battery.

1. The experience calculation method

Based on our pilot experience, the following formula can also be used to easily estimate the required battery capacity under wind conditions. The type is:

Q-- Required capacity of lithium battery (ampere hour);

P -- Load power (watts);

T -- Daily electricity hours;

U-- Standard lithium battery voltage (generally 12V);

N -- Battery storage cycle coefficient; (according to the wind condition, generally take 3-8 days)

K-- Discharge control coefficient, (0.75~0.8)

On type considered: (1) rated power of electrical equipment, (2) local meteorological condition, namely calm period average time, was to prevent the lithium-ion battery over discharge, discharge should be controlled in a certain degree.

For example, a 100-watt machine is installed to provide electricity for 3 households. Each household is equipped with 12 volts and 15 watts of light bulbs and 2 bulbs for an average of 5 hours a day to calculate the required lithium battery capacity. (6 reserve coefficient and discharge coefficient 0.8) can be substituted into the formula to obtain:

When choosing six pieces of l2 voltage 48 lithium-ion batteries, the total capacity of 288 ampere hour.

2. The power balance calculation method.

Calculation steps are as follows:

A. according to local meteorological department, the wind speed data provided in ten days for a degree, ten-day respectively by statistical fan wind speed to stop the wind from starting work hours occurred within the scope of the different wind speed.

B. the wind turbines according to choose P = f (V) characteristic curve and wind speed data, computing - machine by ten-day can's electricity, and draw the annual output process curve. Drawn according to wind speed data computing are grazing factory ED1.5-100 type fan power generating capacity of the process line. Calculated the machine under the local wind conditions, power generating capacity is 276 degrees. Capacity change a lot from the process line to see the ten-day, more in late April 19 degrees, less in late February, nearly 20 times of only 0.95 degrees, configure lithium-ion battery for energy storage adjustment is necessary.

C. According to the situation of telecommunication, the electricity consumption per decade is calculated, and the annual electricity consumption process line is given.

D. Compare the generation and consumption process lines to determine the required lithium battery capacity with the amount of electricity generated at a time when the generation is less than the electricity difference. The difference is 2.3 degrees. It needs to be equipped with 2300 volt-ampere hour battery, and 4 lithium batteries of 12v and 48h are actually selected. Total capacity 2304 volt ampere hours.

When determining the standard battery, it must be noted that the capacity of the storage oil group should be able to safely accept the current intensity max of the wind turbine output.

Because the wind speed often changes, the output current of the motor is sometimes large or small, and sometimes none, so it is difficult to determine the charging current of lithium ion battery and the required charging time. In view of this practical situation, we use the above two calculation methods to determine the capacity of lithium battery configuration.

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