The 12V lithium iron phosphate battery (batterie) quick charging is restricted by both material and thermal management. Byd’s Blade Battery technology proves that its 12V/100Ah LiFePO4 battery pack indeed possesses 2C quick charging capability (200A current), and 80% charging can be realized within 30 minutes. However, it must be within the temperature range of 25-45℃. Once the range is exceeded, the BMS system will actively limit the charging rate to 0.5C. The Fraunhofer Institute’s test data in Germany show that when the battery is charged with 1.5C (150A) at an ambient temperature of 30℃, the internal temperature difference is within 3.2℃, and the cycle life is up to 3,000 times (capacity fade to 80%). Yet, if charging is boosted to 2C, the life will be reduced to 2,200 times, and the attenuation rate will be 37% higher.
The efficiency of the charging infrastructure has a direct influence on the impact of fast charging. The Tesla Powerwall specialty charger uses an 800V high-voltage architecture. When boosting and charging the 12V LiFePO4 batterie, the energy conversion efficiency is 94%, 12% higher than that of the traditional 12V adapter. The actual test conducted by Clore Automotive of America shows that the use of intelligent pulse charging technology (with the frequency of 120Hz) has the effect of reducing the charging time from the conventional 4 hours to 1.8 hours, and at the same time reduce the polarization effect by 52%. CATL unveiled its third-generation lithium battery fast-charging solution in 2024, reducing the standard deviation of the temperature difference of a single battery from 5.1℃ to 1.8℃ through a three-dimensional heat conduction structure. It achieves 1C charging in an environment of -20℃, with the low-temperature charging speed increased by 400% compared to the previous generation technology.
Safety requirements strictly limit the boundaries of fast charging. The UN ECE R136 rule requires the power batteries’ surface temperature should not exceed 60℃ when fast charging at 2C, therefore, most of the 12V LiFePO4 battery suppliers restrict the maximum continuous charge current to 1.2C. Japanese standard JIS C8715-2023 demands that the voltage fluctuation of the rapid charging process should be maintained within ±1%, forcing the charger manufacturers to utilize voltage sensors with accuracy of ±0.5mV. A case study of an RV conversion company in Europe reports that following the introduction of a 120A charger with a liquid cooling system (at 35% increase in cost), the full charge time of a 12V/300Ah battery pack was reduced from 14 hours to 6.5 hours, but at an additional modification expense of 480 euros.
Economic analysis shows that the payback time of the investment in fast-charging equipment is relatively lengthy. Let’s take 12V/200Ah LiFePO4 batterie as an example. Compared to the standard 20A charger ($90), the installation of a 100A smart charger (at a cost of $380) reduces the charging time from 10 hours to 2.5 hours, but it needs to be combined with a 2000W inverter (at an 8% efficiency loss). According to calculations by the U.S. Department of Energy, in the scenario of daily charge and discharge cycles on average, fast-charging equipment needs to be run for 4.3 years continuously in order to make up for the original disparity in cost, while battery life loss will increase by 19% the total holding cost. According to China Tower Corporation’s 2023 base station operation and maintenance data, the cycle of replacing 12V battery packs with the use of fast charging solutions is 2.7 years, 23% shorter than that of conventional charging packs.
Technological innovation continues to defy physical limitations. Israel’s StoreDot has come up with the 12V LiFePO4 batterie silicon anode that features 4C charging (80% charged within 15 minutes) under laboratory conditions, and has a volume expansion rate within 3%. BMW and CATL jointly unveiled the “Speed Core” technology in 2024, which increases the diffusion rate of lithium ions by 2.8 times on the basis of a porous electrode structure, so that the 12V auxiliary battery can support 1.5C continuous charging without lithium plating. Industrial statistics show that the size of the global 12V rapid-charging battery market was 4.7 billion US dollars in 2023. However, affected by the缺 chip of BMS (with a 26-week delivery cycle), installation volume merely reached 78% of the target value. It is estimated that by 2028, solid-state electrolyte technology will witness 12V LiFePO4 battery fast charging capacity exceed 3C and the maximum charging temperature as low as 48℃.