Constant-resistance discharging

The discharge mode of Ni-Cd batteries is dependent on their applications. The most common one is the constant-current discharge, in which the current can be changed from very low (e.g., in the case of button-batteries) to very large (e.g., for batteries for wireless tools). There are also other discharge modes, such as constant-resistance discharge, content-power discharge, etc. 

For constant resistance discharge as normally carried out for primary batteries, with R(Q) = constant as resistive load, the following relation applies... 

FIGURE 10.14 Comparison of constant-power, constant-current, and constant-resistance discharge curves of typical AA-size alkaline batteries. , Constant resistance , constant power A, constant current. 

FIGURE 10.16 Constant resistance discharge performance at typical zinc-alkaline batteries at various temperatures to 0.8 volt cutoff voltage, (a) AA-size battery, (b) D-size battery (Courtesy of Duracell, Inc.)... 

FIGURE 10.23 (c) Constant resistance discharge performance at various... 

Figure 12.9 exhibits the t) pical curves for a 11.6 x 3.0 mm sized monovalent silver oxide battery on constant resistance discharge. These are typical voltage curves the discharge voltage profiles of other size batteries would be similar. The service life will vary depending upon the size of the battery and the applied load. 

Ftg. 9.26 Constant load discharge of lithium-iron disulphide thermal battery, Load resistance = 56 ft. (By courtesy of Sandia National Laboratories,)... 

The over-all effect of the methylchlorosilane treatment of steatite is to stabilize the electrical behavior of the surface under widely different conditions of humidity or condensation. The same surface stability is desired in certain types of fluorescent lamps in order to insure dependable starting of the discharge, regardless of the ambient humidity. Such lamps therefore are treated with the methylchlorosilane vapor in order to make the surface water-repellent, in which condition it has a more constant resistivity and a predictable charge distribution. The starting characteristics then are no longer affected seriously by the moisture content of the air. 

Depending on applications, alkaline Zn/Mn02 batteries can be discharged under different conditions, such as constant current, constant resistance, and constant power. In case of the constant current discharge, the capacity utilization can be affected by the applied... 

An alternative approach is to accept whatever rate of feed reaches the compacting screw and press this against a constant resistance to produce a controllable compacting force. This is done by a form of plug seal screw, either with a fixed form of construction, or with the provision of a variable resistance device to increase or decrease the compacting force. Linking the discharge resistance to the drive unit allows the compaction force to be optimized to the drive capacity. 

Equivalent discharging circuits of supercapacitor at constant resistance (a), constant voltage (b), and constant current (c). 

Constant Resistance The resistance of the load remains constant throughout the discharge (The current decreases during the discharge proportional to the decrease in the battery voltage)... 

In the constant-current mode, the current is maintained at a level such that the power output at the cutoff voltage is equal to the level required for acceptable equipment performance. Thus both current and power throughout the discharge are lower than for the constant-resistance mode. The average current drain on the battery is lower and the discharge time or service life to the end of the battery life is longer. 

FIGURE 3.7 Characteristics of a AA size primary battery discharged under constant resistance, constant current and constant power conditions at 5.9 ohms, — — 200 milliamperes, — — and 235 milliwatts, — —. See Sec. 3.2.4 for detailed description. 

FIGURE 14.54 Summary of discharge characteristics of cylindrical (spirally wound) li/MnOj battery (CR123A size) capacity vs. discharge load to 2.0 V per cell, (a) Constant-resistance loads, (b) Constant-current loads. 

Typical discharge curves of the AA-size Li/FeS2 battery under constant-resistance, constant-current, and constant-power discharge modes are shown in Figs. 14.81 to 14.83. 

FIGURE 14.81 Constant resistance continuous discharge of Li/FeSj AA -size batteries at 21°C Courtesy of Eveready Battery Co, Inc.)... 

FIGURE 28.17 Discharge curves of AA-size (650-mAh) nickel-cadmium battery—constant power ( ) vs. constant current (A) vs. constant resistance ( ). 

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