Cell voltage carbon zinc

Carbon-zinc is the generic term for the Leclanche and zinc chloride system. Carbon-zinc cells provide an economical source of electrical energy for low drain applications. The service life depends strongly on the discharge rate, the operating schedule and the cutoff voltage, as well as temperature and storage conditions. 

Carbon-zinc cells are distinguished by the composition of the electrolyte. The Leclanche cell has an aqueous ammonium chloride-zinc chloride electrolyte. The higher performance zinc chloride cell mainly has zinc chloride electrolyte and may contain a small amount of ammonium chloride. Cells are available in cylindrical and flat plate constructions, as well as combinations of cells for higher voltage applications. Approximately 30 billion carbon-zinc cells are manufactured annually. 

Another approach to cell design especially for high-voltage, low-current carbon-zinc cells is the so-called Minimax Construction [3]. 

Alkaline manganese batteries perform similarly to carbon-zinc batteries in that the service hours delivered are greater when the cut-off voltage is lower. The cut-off voltage should be made as low as possible so that the high energy density of the cell can be used. 

Zinc chloride cells are able to operate at higher electrode efficiencies than carbon-zinc cells and hence have a higher useful current output and will operate at higher current drains than carbon-zinc cells of the same size. In addition, the voltage lever under load... 

The closed-circuit or working voltage of a carbon-zinc cell falls gradually as it is discharged (Figure 30.7). The service hours delivered are greater as the cut-off or end-voltage is lower. 

The open-circuit voltage of a carbon-zinc cell decreases on average 0.0004 V/°C when the temperature is decreased from 25°Cto —20°C. For practical... 

Figure 30.7 Voltage-discharge characteristics of a carbon-zinc D cell discharged 2 h/day at 21 °C (fixed-resistance load) (Courtesy of Union Carbide)...

Figure 30.9 Voltage characteristics of D-size carbon-zinc cell discharged at three different temperatures with a continuous current drain starting at 667mA (Courtesyof Union Carbide)...

Figure 30.37 Effect ot temperature onthe capacity of D-sized ceils (a) carbon-zinc dry cells discharged conlinuouslythrough a resistance of 2.25 c to an end-voltage of 0.9 V (b)zinc chloride cells when discharged 4min, 1 h, 8h, 1 day with a 16h rest through a resistance of 2.25 n to a cut-off voltage of 0.9 V (Courtesy of Union Carbide)...

Table 36.1 Typical applications, load, voltage under load and amperage reading for testing cf the most widely used carbon-zinc Leclanche cells and batteries...

Table 54.2 Estimated average service life at 21 °C for a selection of Union Carbide Eveready carbon- zinc Leclanche dry cells and batteries, voltage range 1.5-9V... 

SAFT lithium-thionyl chloride cells exhibit a highly stable service voltage and a far greater capacity than conventional zinc-manganese dioxide and carbon-zinc cells of the same size and configuration. 

---