The total capacity of the 12V 300Ah LiFePO4 battery is 3.6kWh (12V × 300Ah), which can be used for small and medium-sized off-grid or standby power systems. For example, if a family uses 5kWh of electricity daily and has a 1kW solar panel (producing on average 4kWh per day), the battery can charge 72% of the total electricity for the whole day (under the assumption of a discharge depth of 80% at night), lowering the grid’s dependence rate by 60%. But in the case of maximum power load greater than 3kW (current 250A), batteries need to be paralleled or the BMS upgraded to support continuous high-rate discharge.
When it comes to cycle life, the 2,000-5,000 cycles (DOD 80%) of LiFePO4 battery are far better than the 300-500 cycles of lead-acid batteries. Assuming daily charge and discharge, the life can be 5 to 10 years, with a cost of a single cycle as low as ¥0.15/Ah (lead-acid batteries ¥0.35/Ah). For instance, a specific RV operator uses 300Ah power supply using a battery. There is an air conditioner of 1.5kW and a daily usage of 4 hours on average. A single cycle consumes 120Ah (40% DOD), and the battery life can be extended to 10 years (5,000 cycles ×40% DOD equivalent to 2,000 full cycles).
With regard to temperature flexibility, the working temperature range of LiFePO4 battery is between -20°C and 60°C, and its low-temperature performance is superior to ternary lithium batteries (loss of capacity ≤15% at -10°C). But if charging and discharging take place in the -20°C environment, the heating system needs to maintain its efficiency (with additional power consumption of about 5%). The case of the Norwegian polar research station in 2023 shows that this energy storage system with this battery can still have 82% of its useful capacity at -25°C (lead-acid batteries only achieve 35%), but the heating module requires an average daily power consumption of 0.3kWh.
Cost-benefit analysis: 12V 300Ah LiFePO4 battery costs approximately ¥6000-9000 (¥3000-5000 for lead-acid batteries with the same capacity), but the cost per kilowatt-hour throughout the life cycle is as low as ¥0.8/kWh (¥2.5/kWh for lead-acid batteries). Based on an estimated 10-year use period, the total cost saving is approximately ¥15,000 (based on average daily electricity consumption of 3kWh). If combined with a photovoltaic system (cost ¥20,000), the payback period is 5 years (saved electricity per year ¥4,000).
Efficiency and time of charging: LiFePO4 battery supports 1C fast charging (300A current). It is charged from 0 to 100% in just 1 hour (6-8 hours for lead-acid), and the efficiency of charging is ≥95% (70-85% for lead-acid). For example, an off-grid farm charges a 300Ah battery using a 30A solar controller. During 5 hours of average sunlight exposure per day, it will recharge 150Ah (or 50% of capacity), whereas a lead-acid battery will recharge 105Ah only.
Weight and space advantages: The 300Ah lifepo4 battery weighs approximately 30kg (72kg for lead-acid batteries of the same capacity), and its volume is 40% smaller (0.12m³ vs. 0.2m³). For RV or ship drivers, saving weight can lower fuel consumption by approximately 5% (saving 0.5 liters per 100 kilometers), and for 20,000 kilometers of driving per year, it can save ¥4,000 in fuel cost.
Safety and Maintenance: Thermal runaway temperature of LiFePO4 battery is up to 270°C (150°C for ternary lithium batteries), with no memory effect and virtually no maintenance required. In 2022 fire department statistics, the accident rate of LiFePO4 in lithium battery energy storage fires was merely 0.003% (0.12% for ternary lithium batteries). However, it has to be guaranteed that the BMS is given protection against overvoltage/undervoltage (±0.05V threshold accuracy) so that a deviation in a single-cell voltage by more than 0.2V doesn’t cause imbalance of capacity.
Summary of relevant applications:
House energy storage: Equipped with a 3kW inverter, it is capable of supplying simple loads such as a refrigerator (150W) and lights (200W) for 8-10 hours.
Rv/Ship: Compact lightweight design and continuous round-the-world operation of the air conditioner (1.5kW) for 2 hours (25% electricity used).
Off-grid photovoltaic: 50% daily charging can meet the lowest 3kWh requirement with a 48-hour overcharge period on rainy days (DOD 80%).
Telecommunication base stations: They can sustain 72 hours of power supply to telecommunication equipment (with load of 500W) under -20°C conditions.
If your daily power consumption is ≤4kWh and high cycle life and fast charging are needed, LiFePO4 battery is optimal. If the power load is more than 5kW or budget is low (< ¥5000), lead-acid batteries or staged expansion can be adopted.