A Review of Battery Exchange Technology for Refueling of Electric Vehicles

The limited energy storage and long recharge time and of electric vehicle batteries have motivated several alternatives to in-vehicle slow charging. Solutions generally fall into three categories: (1) fast charging, in which batteries are charged in-vehicle at an accelerated rate, (2) battery material reloading or refueling, in which the energy-carrying elements of the battery are physically replaced or replenished, and (3) battery interchange, involving the complete exchange of the battery pack, usually with the aid of some semiautomated mechanism. Among these options, the last, battery interchange, has tended to receive the least industry attention, but has been an expansive topic of invention and novel deployment. This paper reviews battery interchange technology, including discussion of advantages and limitations, the history of battery exchange concepts and implementations, the many possible interchange configurations, novel automation mechanisms, key patents, safety and regulatory considerations, and the economics of fleet and public deployments. Selected case histories will be presented dating from the late 1800’s through the mid-1990's. Commercial and technical impediments will be identified. The full cost of battery interchange, including incremental vehicle costs and infrastructure costs will be assessed, and this will serve as a basis for comparison with slow and fast charging options for fleet and private vehicle operations. Battery interface and configuration standards will be discussed as possible means for facilitating wider-scale deployment. The results of a survey of the EV industry and user community on the perceived viability and acceptability of EV battery interchange will be presented. INTRODUCTION considered the primary reasons for the lack of widespread use of electric cars, trucks and buses. The concept of real-time battery swapping, exchange or interchange, in which vehicle batteries are replaced rather than recharged in-vehicle, has often been considered as a practical means for reducing the refueling time and effectively extending the range of battery-electric vehicles. In situations in which it is practical, battery interchange may be considered an alternative to high-rate in-vehicle battery charging, hybrid power systems, fuel cells, or exchange of the entire vehicle. Any advantages relative to these options must, however, be considered against the significant materials handling and support infrastructure requirements for vehicular battery exchange. The technical challenges of mechanizing the removal, replacement and off-vehicle charging (or reactivation) have inspired a wide range of novel solutions, with various degrees of success. Historically, only isolated implementations have been demonstrated.