LiFePo4 battery charging efficiency can reach 100%, while the lead-acid battery charging efficiency is only 60%. If there is a 100 watts solar panel, let's say the effective sunlight is 5 hours each day, then the electricity stored in the LiFePo4 battery is about 370Wh, and 230Wh stored by the lead-acid battery, charging efficiency for the LiFePo4 battery is 60% higher than lead-acid batteries.
LiFePO4 batteries have a smooth discharge voltage and can discharge 100% at normal operating temperature. Lead-acid battery discharge is at most 60 - 70% of the depth of discharge. The performance of the lead-acid battery in charging is approximately 60% of the level of LiFePO4, and the energy discharged can only release 60% of itself. Therefore, in practical applications, with the same LED power and brightness, the power supplying time for the LiFePO4 battery system is 2.8 times higher than its lead-acid battery's built-in lighting system.
The lifespan of lead-acid batteries will be greatly shortened if they are often deeply discharged. Frequently in the under charge state and can not be re-charged in time, the resulting high sulfate particles, the active material of the pole plate can not be fully utilized, and the actual capacity of the battery will gradually decrease in the long run. The LiFePO4battery charge and discharge state are reversible, there is no memory effect, can be 100% DOD discharge.
With a volume ratio of up to 100 WH/L, LiFePO4 batteries are smaller than lead-acid batteries. it is more space-independent in terms of installation. The same capacity of LiFePO4 batteries is only half the weight of lead-acid batteries.
For example, LiFePO4 battery 12V 110AH size specification is L*W*H: 260*158*244mm, weight is 15kg; and lead-acid battery 12V 100AH size specification is L*W*H: 407*173*210*236mm, weight is 32.7kg. This is less than half the weight.
After 2000 cycles, the capacity of LiFePO4 batteries still remains at more than 80% of the nominal capacity, basically, the service time will be more than 10 years, while lead-acid batteries need to be replaced in about 2 years.
During the charging and discharging of LiFePO4 batteries, the cathode lithium iron phosphate, and negative graphite undergo opposite volume changes, the total volume of the battery remains unchanged and the diaphragm is under less pressure, which provides greater security for battery safety and cycle life.
During storage, lead-acid batteries must be recharged for 3 months, otherwise, they are scrapped; while LiFePO4 batteries have good storage performance and can be stored for up to 3 years, with no need for recharging and maintenance. A significant reduction in labor costs, but also pollution-free. The storage performance of lithium-ion batteries can be measured by the size of the self-discharge of the charge state. Generally, the capacity loss from self-discharge can be divided into non-recoverable capacity and recoverable capacity. LiFePO4 battery storage performance is superior, monthly self-discharge rate of about 2%, and the capacity recovery rate of 98% or more.
LiFePO4 battery working range of -20 ℃ ~ 60 ℃, that is, in the hot sun and cold state, the battery can work normally. LiFePO4 battery due to the P-O chemical bond in iron phosphate being very strong, even at high temperatures of 500 ℃ will not release active oxygen, and will not appear thermal run away.
Solar street lights have a very small charge and discharge current, most will not be more than 10A, so for the battery, are shallow charge and discharge, this way of working is limited to match the battery. For example, NiMH batteries must be discharged and recharged, otherwise, the life of the battery is affected. For LiFePO4 batteries, however, there is no memory effect, which in turn extends their life.
In practice, the LiFePO4 battery built-in solar street light is also usually built-with high quality and high charging efficiency MPPT controller, which can be charged well in rainy weather, and also equipped with a microwave motion sensor, and intelligent dimming and other high-tech features, to guarantee a good lighting effect, but also greatly reduce the waste of electricity so that the lamps can work perfectly in the months of the rainy season. This allows the luminaire to work perfectly during the rainy season, which can extend its service lifespan up to 12-15 years.
