Experimental Analysis on Performance of Lithium Based Energy Storage Systems for Road Full Electric and Hybrid Vehicles

This paper deals with an experimental evaluation about real performance of lithium based energy storage systems for automotive applications. For this purpose, real working operations of different lithium based storage system technologies, such as Li[NiCoMn]O2 and LiFePO4 batteries, were compared in this paper from the point of view of their application in supplying full electric and hybrid vehicles, taking as a reference the well-known behavior of lead acid batteries. The experimental tests carried out in laboratory were firstly performed on storage cells in stationary conditions, through the use of a bidirectional cycle tester based on the IGBT technology, in order to evaluate, compare and contrast charge/discharge characteristics and efficiency at constant values of current/voltage/power of each storage technology. Then lithium battery packs were experimented in supplying a 1.8 kW electric power train laboratory test bench based on a 48 V DC bus and specifically configured to simulate the operations of full electric and hybrid vehicles on road. The test bench was equipped with an electric brake and acquisition/control system, able to replicate in laboratory the real vehicle conditions and road characteristics on predefined driving cycles at different slopes. The obtained experimental results on both charge/discharge tests and driving cycles evidenced the advantages of using lithium technologies mainly due to their high efficiency, in particular at high current values, obtaining extended driving ranges and reduced recharging times.