Cell shorts in automotive lead batteries for safety applications

Safety requirements in vehicles continuously increase due to more automated functions using electronic components. A reliable power supply is crucial for a safe overall system. A major concern exists in the automotive industry that the lead battery is not an appropriate solution for safe power supply because of so-called sudden failures, most prominently about internal cell shorts. This study intends to help understand the characteristics of internal cell shorts by investigating it in depth in tests and mitigate the fear of internal cell shorts happening in lead batteries. Based on specially for this purpose designed tests it shows how long it takes for cell shorts to develop inside a battery and which operating conditions are critical. It presents diagnostic concepts in order to cope with such events before internal cell shorts impact the battery performance in a way that would put the safe supply by battery power at risk. •Increasing safety requirements in vehicles require a reliable power supply.•Lead batteries are a suitable solution for automotive safety-critical architectures.•Industry concern is focused on sudden failures, especially internal cell shorts.•Internal cell shorts require certain operating conditions to develop.•Critical conditions are identified; the time for cell shorts to occur is evaluated.•A concept for a real-time diagnostic voltage prediction is presented.•The concept shows the current performance of the battery.