Page 335 - Battery Reference Book

30/6 Primary batteries
temperatures between - 10 and +20°C and on constant
resistance loads are also shown in Figure 30.11. The
1.30 I\ discharge characteristics are little affected by whether
the duty is continuous or intermittent.
Stabilized battery characteristics are unaffected by
high temperatures. The mercuric oxide cell has good
high-temperature characteristics: it can be used up to
65°C and operation at 140°C is possible for a few
hours. In general, mercuric oxide batteries do not
I 0.3 A lamp (4 i2 test) \ perform well at low temperatures. However, recent
developments have produced several cell sizes that
have good low-temperature characteristics. For the
mercuric oxide batteries not in this group, there is a
severe loss in capacity at about 4.4"C, and near 0°C
I I 1 1 I 1 the mercuric oxide cell gives very little service except
0 100 200 300 400 500 600 at light current drains.
Total discharge time (min)
The life curve (Figure 30.12) shows the typical
performance of an E12-type cylindrical mercuric oxide
Figure 30.8 Union Carbide dry carbon-zinc 'Hercules' cells,
1.5V total discharge times at 21°C for different closed circuit battery over the temperature range -23 to +71T
voltages (Courtesy of Union Carbide) for current drains encountered in many applications.
Successful operation at temperatures above 120°C for
short periods has been reported, but it is recommended
purposes the actual working voltage at the terminals of that 70°C is not exceeded. Figure 30.13 indicates that
the cell or battery is of more significance than the open- voltage depression is slight at low temperatures when
circuit voltage. Figure 30.9 shows the different voltage drains are 100 pA or less in the large cell types or when
characteristics of a D-size carbon-zinc cell discharged intermittent drains of this order are used with smaller
at three different temperatures. In each case, the cells cells.
are discharged with a continuous current drain which Mallory produce special mercury cells, based on
has an initial value, when a 2.25 load is first applied, the wound-anode construction principle, which are
of 667 mA. (This simulates a 0.5 A lamp.) particularly suitable for use at lower temperatures than
those recommended for normal mercury cells. Thus
30.1.4 Mercury-zinc primary cells Mallory types RM1438, RM1450R and RM2550R
operate efficiently at a temperature 15°C lower than
Typical discharge characteristics at stated current the standard mercury cells.
drains and resistances are given in Figure 30.10.
Figure 30.11 shows the discharge characteristics of
a Vidor K13-4-1499 mercury-zinc battery. This bat- 30.1.5 Lithium types
tery measures 59 x 40 x 59mm and weighs 285 g. Lithium-sulphur dioxide primary batteries
The battery terminal open voltage is 13.56V at 0"C,
13.57V at 20°C and 13.58 Vat 30°C. At a constant dis- Typical discharge curves for the cell at 21°C are
charge of 10 mA the battery has a life of approximately given in Figure 30.14. The high cell voltages and flat
2 years at temperatures between -10 and +20°C, discharge curves, until capacity is almost fully utilized,
decreasing towards 1 year at temperatures outside this are characteristic for this type of cell. Another feature
range. Typical discharge characteristics for this cell at of the cell is its ability to be efficiently discharged over

0 25 50 75 100 125 150 175
Minutes of service
Figure 30.9 Voltage characteristics of D-size carbon-zinc cell discharged at three different temperatures with a continuous current drain
starting at 667 rnA (Courtesy of Union Carbide)