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Other characteristic cuwes 30/19

30.6 Other characteristic curves
a 30.6.1 Internal resistance
E (impedance) -percentage discharge curves
1.0
E
Figure 30.53 shows a plot for a 1.5V alkaline man-
ganese dry cell at 21°C of internal resistance, i.e.
E 0.10 impedance, versus percentage discharge. The change
.- P in resistance is more noticeable at lower temperatures,
0
reaching a maximum when the cell is about 30% dis-
charged (Table 30.3).
1 .Q 10 loo loo0 loo00
Hours of service (weight basis)
1 .o
Figure 30.50 Service life of Duracell lithium-manganese dioxide
cells (to 2V/cell) (Courtesy of Duracell)
0.9
-
c 0.8
14.0 p Q.7
- $ 0.6
-
a
> 12.0
5 0.5
W 0
2 10.0 0.4
P
z 0.3
c 8.0
c
d 0 20 40 60 80 100
6.0 Percentage of discharge
I I I I I I Figure30.53 Cell impedance of a Duracell 0-26 cell at 21°C
10 20 30 40 50 60 70 80 (Courtesy of Duracell)
Houn of transmit-receive service
Figure 30.51 High-temperature storage capability of Marathon
CD-size magnesium BA4836 batteries (Courtesy of Marathon) Table 30.3 Effect of
temperature on internal
resistance of a Union Carbide
Eveready 1.5V (E93) alkaline
manganese cell
Temperature Internal
("C) resistance
(a)
21 0.18
0 0.24
-6.7 0.31
-17.8 0.46
-28.9 0.74
Days -40 1.14
Figure 30.52 Eagle Picher reserve primary manganese dioxide-
magnesium perchlorate battery: capacity retention in activated
state, shown to 1 .OV/cell end-voltage (Courtesy of Eagle Picher)
30.6.2 Service time-wattage curves
these batteries is demonstrated in Figure 30.5 1 for con- Such plots are a useful means of evaluating the high-
ditions in which the batteries were discharged under rate performance of cells and batteries. Figure 30.54
transit-receive conditions after storage at temperatures compares the high-rate capability of various primary
between 21 and 71°C. batteries. The lithium-sulphur dioxide cell maintains
Figure 30.52 shows the capacity retention versus a high capacity almost to 1 h on 10 W rate, whereas
time at two different temperatures for a reserve primary the zinc and magnesium batteries begin to drop off
manganese dioxide-magnesium perchlorate battery. significantly at the 20-50 h rate.