2. Battery concept
2.1. Challenges for the battery package
The battery package must meet the demands of different driving
disciplines: Whereas skid pad, acceleration, and autocross require
high electric power over short distances below 1 km, the endurance
test across a 22 km distance forces a high energy battery.
The typical load profile of the endurance testing cycle is shown
in Fig. 2. Average speed equals about 52.4kmh−1 during the
acceleration periods, and 44.3kmh−1 during the deceleration processes.
Whereas top speed was at 85.5kmh−1, the most frequent
velocities range between 30kmh−1 and 60kmh−1. Maximum
acceleration reaches roughly 19ms−2 (about 2 g). To accelerate
the vehicle, instantaneous specific power, Ps(t) = a(t)·v(t)/m, culminates
at 126Wkg−1, and the average specific power of 40Wkg−1
is required. To move a car weighing 365 kg, this corresponds to an
average drive power of 14.6 kW, and an energy demand of 6 kWh
for a 25min endurance race. Air drag and rolling resistance are
discussed in Section 2.3.