Best practices of cell testing for EFB regarding DCA and high-temperature durability
The automotive industry understands that advanced lead batteries have much improved dynamic charge acceptance (DCA), a key technical parameter for hybrid vehicles. However there have been concerns about side-effects caused by high DCA. Research has demonstrated that these side-effects are related to the way batteries are tested, and not how they actually perform in the car when on the road, in 'real-world' conditions.
This research project with Ford, TU Berlin, Fraunhofer ISC and Moll Batterien aims to create synergy between cell-level testing and ‘real-world’ field tests, to demonstrate that advanced lead batteries can meet all the OEM requirements for current and future micro-hybrids. This growing market is predicted to represent 80% of new cars in Europe by 2030, and provides higher fuel efficiency combined with reduced CO2 emissions in vehicles.
By improving cell-level test methods, this project will allow material developers and battery manufacturers to improve the performance of automotive lead batteries.
This collaboration involving Ford, a leading automotive company, means that the most innovative and highest-performing lead batteries will be available for future vehicles.
At Fraunhofer ISC, the work in the last six months involved weight loss and gas flow measurements on 2 V laboratory cells by applying different overcharge tests under various conditions. It is very crucial to determine accurate weight losses in small laboratory cells to perform high temperature tests, as these cells differentiate significantly from commercial automotive batteries.
At TU Berlin, 2 V laboratory cells containing different cell layouts were extracted from selected 12 V automotive batteries (EFB type) to perform DCA and water consumption tests. Both static overcharge test and new key life test (nKLT) were scaled down to 2 V cell-level. Important findings including correlation between charge balance and weight loss were concluded.
This project gives a comprehensive picture of water loss, corrosion and dynamic charge acceptance. These best practice cell-level evaluation methods can possibly be utilized by material developers and battery manufacturers to improve the performance of lead batteries. By doing this, a significant acceleration of R&D towards the challenging KPIs stated in the CBI technical roadmap can be facilitated.