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6.1
Chapter 6.1

Battery/fuel-cell EV design

packages

John Fenton and Ron Hodkinson

6.1.1 Introduction 6.1.2 Electric batteries

The rapidly developing technology of EV design pre- According to battery maker, Exide, the state of de-
cludes the description of a definitive universal package velopment of different battery systems by different
because the substantial forces which shape the EV suppliers puts the foreseeable time availability for the
market tend to cause quite sudden major changes in principal battery contenders, relative to the company’s
direction by the key players, and there are a number of particular sphere of interest, lead–acid – as in Fig. 6.1-1a.
different EV categories with different packages. For
passenger cars, it seems that the converted standard
IC-engine driven car may be giving way to a more 6.1.2.1 Advanced lead–acid
specifically designed package either for fuel-cell electric
or hybrid drive. While the volume builders may lean The lead–acid battery is attractive for its comparatively
towards the retention of standard platform and body low cost and an existing infrastructure for charging,
shell, it seems likely that the more specialist builder will servicing and recyclable disposal. A number of special
try and fill the niches for particular market segments high energy versions have been devised such as that
such as the compact city car. It is thus very important to shown at (b), due to researchers at the University of
view the EV in the wider perspective of its market and Idaho. This battery module has three cells, each having
the wider transportation system of which it might a stack of double-lugged plates separated by micropo-
become a part. rous glass mats. High specific power is obtained by using
Because electric drive has a long history, quite a large narrow plates with dual current collecting lugs and a
number of different configurations have already been 1:4 height to width aspect ratio. Grid resistance is thus
tried, albeit mostly only for particular concept designs. reduced by shortening conductor lengths and specific
As many established automotive engineers, brought up energy is improved by plates that are thinner than
in the IC-engine era, now face the real possibility of conventional ones. They have higher active mass utili-
fuel-cell driven production vehicles, the fundamentals zation at discharge rates appropriate to EV use. At an

of electric traction and the experience gained by past operating temperature of 110 F specific energy was
EV builders are now of real interest to those contem- 35.4 Wh/kg and specific power 200 W/kg. Over 600
plating a move to that sector. A review of the current discharge cycles were performed in tests without any
‘state of play’ in sole electric drive and associated serious deterioration in performance. The table at (c)
energy storage systems is thus provided, while hybrid lists the main parameters of the battery. The US com-
drive and fuel-cell applications will be considered in pany Unique Mobility Inc. have compared advanced
Chapter 7.1. lead–acid batteries with other proposed systems. In

Lightweight Electric/Hybrid Vehicle Design; ISBN: 9780750650922
Copyright Ó 2001 John Fenton and Ron Hodkinson; All rights of reproduction, in any form, reserved.