The total energy capacity of the 12.8V 200Ah LiFePO4 battery is 2.56kWh (12.8V × 200Ah), which can be utilized for providing backup power to critical loads in the home such as refrigerators, lighting, and routers. Assuming the home critical load total power is 500W (150W refrigerator + 100W lighting + 50W router + 200W others), this battery can last around 4 hours (2.56kWh × 0.8 ÷ 0.5kW = 4.1 hours) at 80% depth of discharge (DOD). For instance, during the Texas USA snowstorm of 2023, a certain family used this battery to power the aforementioned load. It was cycled once a day (for 4 hours) during the outage and operated continuously for 5 days (with total of 5 cycles). The capacity of this battery decreased only by 0.1% (with overall loss 0.5%).
In the efficiency factor, the charging and discharging efficiency of LiFePO4 battery is as high as 95% (while that of lead-acid batteries is only 80-85%). When combined with a 1kW solar panel (averaging 4kWh per day), the battery will be completely charged within 5 hours (with a charge current of 40A and a charge power of 512W), equating to an energy loss of approximately 0.128kWh (5 hours × 512W × 5% loss). If charged on mains electricity (with 98% efficiency), the cost per kilowatt-hour is ¥0.6 (assuming electricity costs ¥0.6/kWh), and the cost of one full charge is approximately ¥1.54 (2.56kWh × 0.6 ÷ 0.98). Compared to lead-acid batteries (with an efficiency of 80%), each charge saves ¥0.31 (2.56kWh × 0.6 × (1/0.8-1/0.95)).
In terms of cycle life, the LiFePO4 battery can be cycled 3,500 times at 80% DOD (capacity retention rate ≥80%), and can supply 8.96MWh of energy (2.56kWh × 3,500 times) in its life cycle. Assuming that power outage will result in 50 charge and discharge events annually (for 0.14 times a day), the battery lifetime will be 70 years (3500 ÷ 50) much more than 3 to 5 years for lead-acid batteries (300 charge and discharge of lead-acid batteries), for 60 times a year, assuming a life of 5 years). Its initial cost is as low as ¥0.03/kWh (price of battery ¥4000 ÷ 8.96MWh) in comparison to that of lead-acid batteries at ¥0.12/kWh (price ¥2000 ÷ 1.536MWh).
Adjustable temperatures by lifepo4 battery are -20°C to 60°C, ≤80% (low-temperature capacitive retention rate; capacity of lead-acid batteries will drop to 50% at -10°C). For instance, a family in Canada was powered with electricity from this battery under an environment of -15° C. Under three hours of continuous usage, the actual released capacity was 1.92kWh (2.56kWh × 0.8 × 0.93), which was still capable of supporting a 500W load for 3.84 hours. Under the same condition, the lead-acid battery only had the capability to support power for 1.92 hours (capacity loss + low-temperature loss).
Cost-benefit analysis
Initial investment: ¥4,000 (LiFePO4) vs. ¥2,000 (lead-acid), although the LiFePO4 life cycle cost is 72% lower.
Maintenance cost: Zero for LiFePO4 (acid in lead-acid requires periodic topping up with water, approx. ¥200 per year).
Space efficiency: LiFePO4 takes up a volume of 0.06m³ (lead-acid 0.12m³) and has a weight of 24kg (lead-acid 60kg) with a space saving of 50%.
Safety and reliability: The thermal runaway temperature of LiFePO4 battery is ≥270°C (150°C for ternary lithium batteries), and the BMS real-time monitors the deviation of voltage fluctuation (threshold ±0.05V) to prevent overcharging/overdischarging. 2022 statistics show that fire probability of LiFePO4 household energy storage systems is 0.001% (probability of leakage/short circuit due to lead-acid: 0.01%).
Example scenarios applicable to it:
Round-the-clock short-duration power disruptions: Can handle 500W loading for 4 hours, equal to 90% of regional power outage occurrences (U.S. Department of Energy data with an average of 2.5 hours in power disruption time).
Battery endurance during severe weather: As soon as the loading decreases to 300W (i.e., for refrigerator and router only), battery life rises to 6.8 hours (2.56kWh × 0.8 ÷ 0.3kW).
Off-grid supplement: With 1kW solar power, it can be completely off-grid on clear days, and has a 48-hour buffer period on cloudy and rainy days (with an average daily power consumption of 2kWh).
If the home load is over 1kW (such as an air conditioner + water heater), there should be multiple groups of batteries in parallel or a higher voltage system such as 48V 100Ah should be selected. However, for small and medium family backup needs, the 12.8V 200Ah LiFePO4 battery is superior to the traditional lead-acid alternative in terms of efficiency, life and safety.
