Economically, 12V 100Ah LiFePO4 batterie will cost approximately $600, while the same capacity AGM battery is $180. But its cycle life is 3,000 times (80% deep discharge), which is far greater than the cycle life of AGM (500 times). It is estimated by the U.S. Department of Energy, under a 50% daily charge and discharge scenario, the total holding cost of LiFePO4 over 10 years is $0.15 per Ah, 60% lower than that of AGM at $0.38 per Ah. Statistics from Tesla’s 2023 energy storage project are as follows: after 1,000 AGMs replaced by LiFePO4, the rate of battery replacement decreased to 2.1 years/time to 8.5 years/time, and maintenance cost decreased by 74%.
Comparison of performance indexes shows that the charge and discharge efficiency of LiFePO4 battery achieves 95-98%, 15 percentage points higher than the charge and discharge efficiency of AGM, i.e., 75-85%. German TUV testing reveals LiFePO4 is still able to supply 88% capacity in cold environment at -20℃, while the capacity of AGM goes below 50% in this case. While renovating China Tower Corporation base stations, voltage fluctuation standard deviation using LiFePO4 backup power supply decreased from 0.45V of AGM to 0.12V, and equipment failure rate decreased by 63%. Measured data from Norwegian fishing boats reveal that the special energy density of LiFePO4 is as high as 120Wh/kg, 3.4 times that of AGM (35Wh/kg), decreasing the weight of the hull by 1.2 tons and fuel efficiency by 9%.
As regards safety and ecological protection, thermal runaway temperature of LiFePO4 batterie is up to 270℃, much greater than the critical value of 60℃ of AGM. In UL 1973 certification testing, the maximum temperature of LiFePO4 after stabbing with a 5mm steel needle was not more than 58℃, while the percentage of thermal runaway possibility of AGM under the same conditions was 23%. EU’s “Battery Sustainability Regulation” effective from 2024 requires on-board battery recycling efficiency to be as high as 95%. The recycling efficiency of LiFePO4 cathode materials is as high as 98.2%, and AGM’s lead recycling has to pay an additional processing cost of 0.12 US dollars per kilogram. The statistics of the California solar energy storage project show that due to its maintenance-free nature, the LiFePO4 system’s operating and maintenance expense per year is merely 17% of that of the AGM solution.
The payback period calculation shows that, taking the off-grid system of recreational vehicles as a reference, the cost of upgrading to LiFePO4 batterie is $420 more at first, but the annual savings on fuel costs (owing to weight savings) and battery replacement cost are $230, and the static payback period is 1.8 years. According to a 2023 survey conducted by the American Touring Car Association, 87% of customers who made the transition to LiFePO4 gained a cost savings within two years, and achieved a median reduction in battery capability of only 3.2% per year, significantly less than the 8.5% of AGM. The MTN South African telecom operator’s base station renovation proves that after LiFePO4 replaced AGM, the recovery time after power outage was reduced by 41%, and network availability improved from 99.2% to 99.97%.
Technically, the operating voltage range of LiFePO4 batterie (10V-14.6V) has a strong overlap with that of AGM (10.5V-14.4V), but an exclusive BMS needs to be configured to prevent over-discharge. Test data of Victron Energy in Germany show that after the optimization of charging curve (during the phase of constant current, current is increased up to 0.5C), full-charging time of LiFePO4 can be decreased from 7 hours of AGM to 3.2 hours. By 2024, the global lithium battery price will decline 18% year-over-year, while AGM will increase by 7% due to the volatility of lead prices (with a yearly standard deviation of 23.5%). By 2027, LiFePO4’s base cost is forecast to decline to 1.8 times AGM, driving the rate of substitution to 61% from 28% in 2023.