Methodologies for the evaluation of the battery state of charge in fuel cell systems

The electric storage equipment plays a relevant role in the framework of the minimum impact vehicles. Speaking about both electric and hybrid vehicles the battery still remain a necessary subsystem in order to realise an energy buffer and/or a power buffer. Normally the batteries (i.e. lead acid, Ni–MeH, semibipolar) are delivered from the manufacturers without a SOC (State of Charge) indicator. In this article it will be approached a methodology to estimate the state of charge of a battery using only the current and voltage signal.

The algorithm came from a previous patent of Centro Ricerche FIAT and it will be specially modified in order to be applied to a battery system of an electric vehicle propelled by a 15 kW motor and with a 5KW fuel cell auxiliary power unit.

The aim of the technology is to overtake the difficulties from the use of in-site sensors (i.e. optical or chemical). The technology will be tested in numerical simulation

The algorithm was implemented on the control unit onboard the Seicento Elettra with APU Fuel Cell with the objective to manage the traction battery state of charge (SOC) with the activation or the deactivation of the fuel cell system.