Aging and performance comparison of absorbed glass matte, enhanced flooded, PbC, NiZn, and LiFePO4 12V start stop vehicle batteries

Engine start-stop systems have been widely adopted for internal combustion engine passenger vehicles, with low voltage 12 V systems currently capturing most of the market. While absorbed glass mat (AGM) lead-acid batteries are commonly used for this application, there is interest in other battery types to reduce cost or improve performance. This work examines a range of battery types and compares experimentally determined performance and aging characteristics. Six different start/stop batteries are tested, including two AGM, an enhanced flooded lead acid (EFB), lead carbon (PbC), nickel zinc (NiZn), and LiFePO4 battery. The batteries are aged with a series of start-stop microcycles, which consist of an accessory power and engine-starting discharge pulse followed by a charging pulse. Thirty thousand microcycles correlate with the conditions a start-stop battery would be exposed to over approximately 160,000 km of driving in a typical North American application. The testing procedure begins with two characterization tests - a capacity and HPPC charge and discharge resistance test - and is followed by 3,000 microcycles to age the battery. Characterization and aging tests are repeated until the battery is no longer able to perform the microcycles, and substantially different aging and performance characteristics are observed for each battery.