Method for detecting the capacity of a lithium battery

At present, in the battery market, the application of lithium batteries is more and more extensive. Lithium batteries have a high density, which is five times that of lead-acid batteries. At the same time, the life of lithium batteries is greatly increased compared with lead-acid batteries. The number of times of charge and discharge of lithium batteries is 1000 times. In theory, it can be used for ten years, while lead-acid batteries can only be used for three years, so that the cost will be saved from the future a lot. The self-discharge of lithium batteries is still very low and there is no memory effect. * An important one is that lithium batteries are non-polluting and meet the standards advocated by China. I believe many people have used lithium batteries, so how do we determine the capacity when we buy lithium batteries?

Generally, the conventional charging is "two-stage constant current charging". This method does not waste power, and the charging time is short, which is advantageous for extending the service life of the lithium battery, and it is also much easier to calculate the capacity of the lithium battery. The case of wind power is different from conventional charging.

Whether the lithium battery capacity allocation is reasonable or not directly affects various technical and economic indicators of wind power generation. The capacity selection is small, and the surplus power generated when the wind is too windy is not fully stored. The capacity selection is too large, one increases the investment; the second lithium battery may be in a state of charge dissatisfaction for a long time, which will affect the efficiency and service life of the lithium battery. Table 1 shows the investment of lithium batteries in wind power generation equipment.

Empirical calculation

Based on our pilot experience, the following formula can be used to easily estimate the required battery capacity. In the formula:

Q--The required lithium battery capacity (Ah);

P--load power (watts);

T--day hours of electricity;

U--standard lithium battery voltage (generally 12 volts);

n--Battery reserve cycle coefficient; (determined according to wind conditions, generally take 3~8 days)

K--discharge control coefficient, (take 0.75~0.8)

The above formula considers: 1 rated power of the electrical equipment, 2 local meteorological conditions, that is, the average time of the no wind period, 8 in order to prevent the lithium battery from being over-discharged the discharge should be controlled to a certain extent.

For example, install a 100-watt machine for 3 households to use electricity. Each household is equipped with a 12-volt 15-watt bulb. The average lighting is 5 hours per day, and the required lithium battery capacity is calculated. (The reserve coefficient is taken as 6, the discharge control coefficient is taken as 0.8) and the formula is obtained:

Choose 6 l2 volt 48 ampere lithium batteries with a total capacity of 288 ampere hours.

2. The balance calculation method.

The calculation steps are as follows:

a. According to the wind speed data provided by the local meteorological department, the wind speed from the initial working speed of the wind turbine to the different wind speeds within the range of the stop wind is counted separately for ten days.

b. According to the P=f(V) characteristic curve and wind speed data of the selected wind turbine, calculate the amount of electricity that can be emitted by the machine, and plot the annual power generation process curve. According to the wind speed data, the annual power generation process line of the ED1.5~100 type fan of Shangdu Animal Husbandry Plant is calculated. It is calculated that the annual power generation of the aircraft is 276 degrees under local wind conditions. From the process line, it is seen that the power generation of each tenth varies greatly. *More than 19 degrees in late April, * less than 0.95 degrees in late February, the difference is nearly 20 times, indicating that it is necessary to configure the lithium battery for energy storage adjustment. .

According to the telecom condition, C calculates the electricity consumption for the ten-day period and gives the annual electricity consumption process line. The dotted line in the drawing shows.

d. Compare the power generation and power consumption process lines to determine the required lithium battery capacity by generating electricity at a time less than the power consumption difference* (the shaded portion in the figure). The difference * has a power of 2.3 degrees. Need to configure 2300 volt-hour battery, the actual choice of 12 volts 48 ampere lithium battery 4 pieces. The total capacity is 2304 VA.

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.

Since the wind speed often changes, the current output by the motor is large and small, sometimes not, so the lithium battery charging current and the required charging time are difficult to determine. For this practical situation, we use the following two calculation methods to determine the capacity of the configured lithium battery.

The page contains the contents of the machine translation.