PhD Thesis - Energy Systems Research Unit - University of Strathclyde

NV = Number of Vehicles
However, information about minimum discharge levels is not generally quoted
for electric vehicles, so it is not easy to tell how much of this is actually
available to the driver. The second method is the same as that described earlier
for the other types of fuel, where,
AS = FC x R x NV (5.12)
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Where AS = Available Storage (kWh)
FC = Fuel Consumption (kWh/100km)
R = Range (km)
NV = Number of Vehicles
This is a more useful method of calculating the storage capacity of an electric
vehicle as it eliminates the problems of minimum discharge level, which can be
misleading, and calculates the total capacity actually available. In this case, the
output graph at the matching stage shows the percentage of available battery
capacity.
The recharging of a battery generally takes place in three stages, two of which
can be seen in Figure 5.2 [3]: -
• Bulk Charge - the battery is charged using a constant current until it
reaches around 70 or 80% charge. This is the maximum safe charging current
that does not cause overheating in the cables.
• Absorption Charge - as the battery gets close to full charge, the internal
resistance increases. To avoid damage and overheating, the charging voltage
remains constant, while the current decreases exponentially.
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