Page 239 - Lindens Handbook of Batteries

ZINC-CARBON BATTERIES—LECLANCHÉ AND ZINC CHLORIDE CELL SYSTEMS 9.33

FIGURE 9.32 Capacity retention after storage at 40, 20, and 0°C for paper-lined plastic seal zinc
chloride batteries.

the loss. Refrigerated storage will increase the shelf life. Figure 9.32 shows the retention of capacity
of a zinc-carbon battery after storage at 40, 20, and 0°C. The capacity retention of a zinc chloride
battery is higher than that of the Leclanché type because of the improved separators (coated paper
separator types), sealing systems, and other materials used in that design.
Leclanché-type batteries, using the asphalt or pitch-type seals in conjunction with paste-type
separators, have the poorest capacity retention. Zinc chloride batteries, using highly crosslinked
starch-coated paper separators in conjunction with molded polypropylene or polyethylene seals,
provide the best retention.
Batteries stored at –20°C are expected to retain approximately 80 to 90% of their initial capacity
after 10 years. Since low temperatures retard deterioration, storage at low temperatures is an advanta-
geous method for preserving battery capacity. A storage temperature of 0°C is very effective.
Freezing usually may not be harmful as long as there is no repeated cycling from high to low
temperatures. Use of case materials or seals with widely different coefficients of expansion may lead
to cracking. When batteries are removed from cold storage, they should be allowed to reach room
temperature in order to provide satisfactory performance. Moisture condensation during warm-up
should be prevented as this may cause electrical leakage or short-circuiting.

9.7 SPECIAL DESIGNS

The zinc-carbon system is used in special designs to enhance particular performance characteristics
or for new or unique applications.

9.7.1 Flat-Pack Zinc/Manganese Dioxide P-80 Battery

In the early 1970s, Polaroid introduced a new instant camera-film system, the SX-70. A major inno-
vation in that system was the inclusion of a battery in the film pack rather than in the camera. The
film pack contained a battery designed to provide enough energy for the pictures in the pack. The
concept was that the photographer would not have to be concerned about the freshness of the battery
as it was changed with each change of film.