The performance of high power VRLA ORBITAL™ batteries is presented. These batteries have been designed with isolated cylindrical cells, providing high reliability to the recombination process, while maintaining, at the same time, a very high compression (>80 kPa) over the life of the battery. Hence, the resulting VRLA modules combine a high rate capability with a very good cycle performance. Two different electrochemically active material composit. The performance of high power VRLA ORBITAL™ batteries is presented. These batteries have been designed with isolated cylindrical cells, providing high reliability to the recombination process, while maintaining, at the same time, a very high compression (>80 kPa) over the life of the battery. Hence, the resulting VRLA modules combine a high rate capability with a very good cycle performance. Two different electrochemically active material compositions have been developed: high porosity and low porosity for starting and deep cycle applications, respectively (depending on the power demand and depth of discharge). Although, the initial performance of the starting version is higher, after a few cycles the active material of the deep cycle version is fully developed, and this achieves the same high rate capability. Both types are capable of supplying the necessary reliability for cranking at the lowest temperature (−40°C). Specific power of over 500 W/kg is achievable at a much lower cost than for nickel–metal hydride systems. Apart from the initial performance, an impressive behaviour of the cycling version has been found in deep cycle applications, due to the highly compressed and high density active material. When submitted to continuous discharge–charge cycles at 75% (IEC 896-2 specification) and 100% (BCI deep cycle) DoD, it has been found that the batteries are still healthy after more than 1000 and 700 cycles, respectively. However, it has been proven that the application of an IUi algorithm (up to 110. Automotive batteriesValve regulated lead-acid batteriesCycle-life testAbsorptive glass matFast chargingHybrid electric vehiclesDuring the next decade, it is expected that electric power demand for new vehicles will change drastically because:••Vehicle electronic content will grow from 10 to 20%.••The number of electric motors will be increased by 30%.••Emissions, fuel economy, and safety standards are expected to become more restrictive.••Weight reduction and improved engine efficiency will reduce fuel consumption by 10–15%.Recently, continuous manufacturing techniques for the large scale production of plates have been developed which, together with an automated assembly process, allow the objectives in costs and performance required to be achieved by a valve regulated battery. The individual cells include rather thin plates and polyester/glass mat separators wound with a very high compression (>80 kPa) that can be easily maintained throughout life by using the cylindrical cell design. This design is increasingly being used in the manufacture of automotive batteries with high engine starting capacity and will be very suitable for the vehicles in development that demand higher power and reliability.Fig. 2 shows a diagram of the arrangement of the cylindrical cells within a high power VRLA battery, which has been subjected to important improvements during the project development process. The most important features are the presence of cooling channels between cells and the use of one valve per cell. Every cylindrical cell body is thermally sealed to the lid, and electrically connected through the partition to the adjacent cell by means of an upper planar area below the lid. In comparison to other designs, the inter-cell welding has been designed to be mechanically robust (increasing the vibration resistance) and to have a highly conductive cross section in order to overcome any heating of the connectors, which would otherwise be a problem due to hig. 3.1. Comparison with other VRLA technologiesAll the design and process features previously mentioned have been developed with the goal to provide a battery that combines good cycling performance with a high rate capability. Fig. 3 shows a comparison with other battery technologies (flat or tubular plate gel versus spiral wound AGM design) that have been used for industrial applications due to their long life characteristics. For similar block dimensions, the low rate performance is very much the same, but at medium rate flat or spiral wound plates have much better performance than tubular plates. At very high rate (more than 2 C or discharge shorter than 0.3 h) the spiral wound design is better than the flat or tubular ones.3.2. Cold cranking performanceDue to its high power capability, one of the most obvious applications is engine starting. A 12 V 50 A h module is able to provide up to 1000 A for more than 30 s with a voltage higher than 2/3 of the open circuit voltage (USABC and EUCAR requirement). This represents a discharge at 20 C, difficult to be sustained by other advanced batteries, such as lithium-based systems. Besides, the lower the ambient temperature, the higher the difference in favour of the VRLA syste.
