Application Of Lithium Iron Phosphate Battery In Solar Street Light

1. Charging efficiency

Lithium iron phosphate battery charging efficiency can reach 100%, while lead-acid battery charging efficiency is only 60%. If 100W solar panels, according to the weather conditions in Shanxi Province, lithium iron phosphate batteries can store about 45W-75W per day, but lead-acid batteries can't reach 27W-45W. Two lead-acid batteries can achieve the charging effect of one lithium iron phosphate battery. In other words, a battery of the same capacity, a lithium iron phosphate battery can supply 60W lamps, and a lead acid battery can only supply 30W lamps.

2. Excellent discharge performance

The lithium iron phosphate battery has a stable discharge voltage and can be discharged 100% at room temperature. Lead-acid batteries have a discharge depth of up to 60-70%. The lead-acid battery is about half the level of lithium iron phosphate battery in terms of charging performance, and the discharge can only release half of the lithium iron phosphate battery. In practical applications, the same 12V40AH battery, lithium iron phosphate battery can release 40AH electric energy, if the street lamp works 10 hours every night, it can work continuously for 2 rainy days; if considering the charging performance is only half of the state, charging for 1 day, lead The acid battery receives 20AH, but can only discharge 10AH of electricity, and can only supply half a rainy day for continuous work.

If the lead-acid battery is frequently deeply discharged, the cycle life will be greatly shortened. It is often in under-charged state and cannot be recharged in time. The sulfate particles produced are large, and the active material of the plate cannot be fully utilized. The actual capacity of the battery will gradually decrease over time. The charge and discharge state of the lithium iron phosphate battery is reversible, there is no memory effect, and it can be discharged by 100% DOD.

3. Small size and light weight

Lithium-ion batteries have a volume ratio of up to 100 wh/l and are smaller than lead-acid batteries. It is more space-free in terms of installation. The same capacity lithium iron phosphate battery weighs only half the weight of lead-acid batteries.

For example, lithium iron phosphate battery 12V110AH size specification length * width * height is 260 * 158 * 244, weight: 15kg; and lead acid battery 12V100AH size specifications: length * width * height * total height: 407 * 173 * 210 * 236 (mm), weight: 32.7 kg. It is obvious that the lithium iron phosphate battery is smaller in size and less than half the weight.

4. Long service life and low maintenance cost

After 2000 cycles, the lithium iron phosphate battery maintains its capacity at more than 80% of the nominal capacity. Basically, it can be used for 7-8 years, while lead-acid batteries need to be replaced in half a year to one year.

During the charging and discharging process of lithium iron phosphate battery, the positive volume of lithium iron phosphate and negative graphite changes, the total volume of the battery does not change, the pressure of the diaphragm is small, and the safety of the battery and the cycle life are greatly guaranteed. .

When storing, the lead-acid battery must be recharged for 3 months, otherwise it will be scrapped; and the lithium iron phosphate battery has good storage performance and can be stored for up to 3 years without replenishment and maintenance. Significantly reduced labor costs and no pollution.

The storage performance of a lithium ion battery can be measured by the size of the self-discharge in the charged state. Generally, the capacity loss of self-discharge can be divided into non-recoverable capacity and recoverable capacity. The lithium iron phosphate battery has excellent storage performance, and the monthly self-discharge rate is about 2%, and the capacity recovery rate is over 98%.

According to 1000 lamps, the maintenance cost required for the calculation of the 8-year cumulative life time is:

Lead-acid battery 4000 yuan × 1000 lights × 8 = 32 million yuan

Lithium iron phosphate battery 0 yuan

5. Wide operating temperature range

The working range of lithium iron phosphate battery is -20 ° C ~ 60 ° C, that is, in the hot sun and cold conditions, the battery can work normally. Since the lithium iron phosphate battery has a very strong P-O bond in iron phosphate, it does not release active oxygen even at a high temperature of 500 ° C, and thermal runaway does not occur.

The normal working range of lead-acid batteries is 20-30 ° C. When the battery temperature is too low, the capacity is reduced because the electrolyte is not well reflected with the active material of the board under low temperature conditions. The capacity reduction will not meet the expected backup time and remain within the specified discharge depth, which can easily cause overdischarge of the battery. At normal temperature, an ideal controller can make the lead-acid battery fully charged, but when the ambient temperature drops to 0 °C, the same controller is used to charge, and the result is not enough. The same reason, when the ambient temperature rises When it is high, it will easily cause over-charging, and the temperature of the electrolyte will increase the corrosion rate of the positive plate. When the working temperature of the lead-acid battery rises seriously, it will boil. The electrolyte that rolls up and down washes the plate and makes the lead powder. Falling off, for a long time, the lead powder that has fallen off will accumulate and become higher. When the lead plate is hit, the plate can be short-circuited and the battery can be scrapped. When working in a high temperature state, lead-acid batteries may also suffer from water loss and thermal runaway, which is very dangerous.

6. Best match with street lamp charging and discharging status

The charging and discharging current of the street lamps is very small, and most of them do not exceed 10A. Therefore, for the battery, the shallow charging is shallow, and this working mode limits the matching battery. For example, a nickel-hydrogen battery must be recharged, otherwise it will affect the life. For lithium iron phosphate batteries, there is no memory effect, but it will prolong the service life.