EV Technology


Batteries

Range has been the Achilles heel of EVs compared to cars with internal combustion engines for the last century. The properties of the electrochemical energy storage medium, also known as the battery, decide how much energy can be stored and subsequently transformed into propulsion. Development of the lithium ion and lithium polymer battery families has shown significant improvement in gravimetric and volumetric energy capacity during the last 20 years. Based on the current market situation and estimated utilisation areas for different chemistries the EDISON project chose to purchase Li-ion manganese spinel and lithium iron phosphate batteries for laboratory studies.

In WP 1.5 a simulation-model was developed in order to evaluate the effects that use-pattern has on EV battery degradation and lifetime. From a user perspective, the important parameters relating to an EV battery is energy capacity, efficiency and remaining lifetime. These parameters are strongly dependent on a number of variables such as temperature, depth-of-discharge (DOD), charge and discharge rates and cycle number. This means that battery use affects battery performance.

 

Sketch of the structure of the battery simulation model developed in WP 1.5.

Plugs and sockets

Plugs and socket outlets have been one of the central topics of the international standardisation effort in the International Electrotechnical Commission (IEC). The upcoming international standard IEC62196-2 will contain three different plug designs known as type-1, -2 and -3. At an early stage in the EDISON project it was decided to support type-2 plug due to three phase capability, interoperability (one plug design for different amp ratings), dedicated signalling pin, high rated power (43,5 kW) and wide support in northern Europe amongst utilities and OEMs. In the beginning of the project the CEE plugs was the only available option. Through the electric vehicle task force (EV TF) in EURELECTRIC, the EDISON project contributed in a joint call for European standards for EV charging by publishing the declaration “Standardisation of Electric Vehicle Charging Infrastructure” together with a unified European electricity industry. Further analyses in the EDISON project show that the three phase charging offers the users a more optimal charging related to the driving patterns than the one phase with a higher current. 

                    

                    

                            

   IEC 62196-2-1 ’SEA J1772’             IEC 62196-2-2 ’Mennekes’                   IEC 62196-2-3 ’Scame’

 

Traffic patterns

The most important difference between EVs and conventional cars is that the EV has to be charged at home every night instead of being fuelled at a fuel station for every 500 km e.g. At days when the car is driving longer distances it also has to be charged outside home in the running of the day. As can be seen in the figure below to the left, 90% drives 100 km per day or less, which today’s modern EVs are capable of, even on days with low temperatures.

 

The figure to the right shows that at a given time more than 92 % of all cars are parked. Even in the middle of the day 95 % of the cars are parking. And after the afternoon peak which is not ending until close to 8 pm 98 % is parked. With over 90% of the EVs parked at a given time, fleet operators can participate in the electricity marked and markets for ancillary services.