EV Internal Charging and Grid-to-Battery Efficiency: An Empirical Study Based on Selected EV and EVSE Models

Supporting the 2015 Paris Agreement on rapid decarbonisation of all economic sectors to limit global warming to
$1.5^{\circ }\mathrm{C}$
above pre-industrial levels, Aotearoa New Zealand (NZ) has committed transitioning to net-zero with the opportunity of reaching a more productive, sustainable and inclusive economy. With a 2030 target of 100% renewable electricity, and 2050 target of carbon-neutral economy, the NZ government has mandated adoption of electric vehicles (EVs) to reduce 39% of domestic
$\text{CO}_{2}\ \mathrm{e}$
missions arising from the transport sector. This paper presents internal efficiency measurements of some of the typical EVs used in NZ with emphasis on maximum charge power transfer against selected AC and DC fast chargers. An efficiency summary of eight electric vehicle supply equipments (EVSEs) adopted within NZ infrastructure is also included in this manuscript to showcase charging performances under various EV loads. Active battery thermal management systems of EVs under study are investigated based on internal charge profiles recorded by power quality meters and OBD2 data (EVSE power vs EV battery power). Overall, it is revealed that the ultimate grid-to-battery efficiency varies from 85% to 92.6%, with significant energy being consumed by the vehicle BMS for battery thermal management.