Page 237 - Lindens Handbook of Batteries

ZINC-CARBON BATTERIES—LECLANCHÉ AND ZINC CHLORIDE CELL SYSTEMS 9.31

Special low-temperature batteries were developed using low freezing-point electrolytes and a
design that minimizes internal cell resistance, but they did not achieve popularity due to the superior
overall performance of other types of primary batteries. For best operation, at low ambient tempera-
tures, the Leclanché battery should be kept warm by some appropriate means. A vest battery worn
under the user’s clothing, employing body heat to maintain it at a satisfactory operating temperature
was once used by the military to achieve reliable operation at low temperatures. Addition of other
salts or gum karaya can boost low-temperature performance at the expense of high-temperature
(>40°C) shelf life.

9.6.8 Service Life

The service life of the Leclanché battery is summarized in Figs. 9.30 and 9.31, which plot the service
life at various loads and temperatures normalized for unit weight (Amperes per kilogram) and unit
volume (Amperes per liter). These curves are based on the performance of a general-purpose battery
at the average discharge current under several discharge modes. These data can be used to approxi-
mate the service life of a given battery under particular discharge conditions or to estimate the size
and weight of a battery required to meet a specific service requirement.
Manufacturers’ catalogs should be consulted for specific performance data in view of the many
cell formulations and discharge conditions. Table 9.8 presents typical data from a manufacturer of
two formulations of the AA-size battery.

9.6.9 Shelf Life
Zinc-carbon batteries gradually lose capacity while idle. This deterioration is greater for partially
discharged batteries than for unused batteries and results from parasitic reactions such as wasteful
zinc corrosion, chemical side reactions, and moisture loss. The shelf life or rate of capacity loss is
affected by the storage temperature. High temperatures accelerate the loss; low temperatures retard

6.0
4.0 6.0
55°C 4.0
2.0 2.0
Amperes/kilogram 1.0 20°C 1.0 Amperes/liter

0.6
5°C
0.6
0.4
0.4
0.2

0.2
0.1
0.1
10 20 40 60 100 200 400 600 1000
Hours of service
FIGURE 9.30 Service hours for general-purpose zinc-carbon battery, discharged
2 h/day to 0.9 V at three temperatures.