Electrical Equipment - Wind Energy Systems for Electric Power Generation - page 69

Fig. 4.20 Ragone diagram of energy storage devices
When charged, and at 25 ◦ C the acid density is 1 , 24 g / cm 3 . The cell voltage is
roughly 2 V, resulting in 12 V for a batter y with 6 cell in series, a number common
from batteries for passenger cars. In fully charged state the voltage is somewhat
larger, at 2,3 V. Figure 4.21 shows the cell voltage over degree of charge, indicating
Fig. 4.21 Cell voltage U overdegreeofcharge p