Amaron Onyx EFB Batteries for Start-Stop These are the highest specification Amaron batteries for vehicles requiring an EFB start-stop technology. EFB (Enhanced Flooded Batteries) are an optimised version of traditional wet lead acid batteries that have been designed to provide higher charge acceptance along with the ability to withstand much higher numbers of vehicle starts. The Onyx uses an Advanced Stamped Grid “Dura Frame” technology, punched from a continuous rolled lead sheet with refined grain Structure for better performance. This provides best-in-class conductivity and optimises the electrical and performance requirements.