BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI

112 Vlad Marţian et al
Current Intensity [A]
80
70
4.5
4
60
3.5
50
3
2.5
40
2
30
1.5
20
1
10
0.5
0
0
0 10 20 30 40 50 60 70
Time [min]
Battery Voltage [V]
Current Intensity Battery Voltage
Fig. 8 – Current intensity and voltage.
Eoc [V]
4
3.5
3
2.5
2
1.5
1
0.5
0
0
0 0.2 0.4 0.6 0.8 1 1.2
0.09
0.08
0.07
0.06
0.05
0.04
Rint [Ω]
0.03
0.02
0.01
SOC
Open circuit voltage Internal Resistance
Fig. 9 – Battery internal parameters.
Chart in Fig. 8 show the current intensity and voltage evolution in time
and Fig. 9 show the battery parameters, Open Voltage E oc and internal
resistance R int function of the battery state SOC.
Another simulation done was with a simple cooling of the battery, and
with a variable load resistor which changes the current drawn over time.
Here we used a convection model to remove the heat from the battery and
an ambient temperature of 20 o C.
In Fig. 12 can be seen that the temperature and the current intensity are
connected but there is a slight shift between the current maximum and the
temperature maximum, this can be explained if we look at Fig. 11 and Fig. 9. In
Fig. 11 can be observed that the maximum temperature is near a SOC of 0 and
from Fig. 9ig. 9 we can see that at SOC near 0 the internal resistance rises so
more heat will be generated.