Experimental Operation Status of Start-Stop Batteries

Engine start-stop systems have captured significant market share in a short period, particularly in Europe, where new vehicles are increasingly equipped with the feature. Vehicles with start-stop functionality have also entered the Chinese, Japanese and US markets. Lower fuel costs and controllable CO2 emissions are the main drivers.

What determines start-stop performance

System performance depends on several factors. On one hand, test conditions vary – multiple vehicle test standards currently coexist, including NEDC, FTP75, JP08 and the newer global WLTP standard. On the other hand, real-world driving conditions matter: driving patterns, traffic norms, climate, driver behaviour, vehicle design and configuration, and the way the start-stop strategy is implemented all influence the outcome.

Battery implications

Frequent stop-start cycling places a demanding duty on the battery. It must accept charge quickly during deceleration and regeneration, deliver reliable cranking after short rest periods, and withstand operation in a high-rate partial state of charge. Conventional batteries struggle in this duty, which is why dedicated AGM and EFB start-stop batteries are specified.

Experimental results from the industry show that battery design, charging strategy and test conditions must be considered together when evaluating start-stop system performance.