Discharge rate capacity curves

Discharge rate-capacity returned (discharged capacity) curves... 

Figure 6. Potential vs. capacity curves obtainedfrom cycling tests of synthetic graphite flakes in EC-PC/LiCIO4 solutions in different discharge rates. Notice that as the discharge rate decreases - the irreversible capacity decreases accordingly.

Pumps that have stable head/capadty curves (continuous head rise to shutoff) are preferred for all apphcations and are required when parallel operation is specified. When parallel operation is specified, the head rise shall be at least 10 percent of the head at rated capacity. If a discharge orifice is used as a means of providing a continuous rise to shutoff, this use shall be stated in the proposal. 

The rated capacity is 0.75 Ah. Typical discharge curves and charge-discharge cycle behaviour of these 3 V batteries are shown in Figs 7.27 and 7.28, respectively. Energy density of 130 Wh/kg and 280 Wh/dm3 and 300 complete cycles at 100% depth of discharge have been reported. The electrolyte solution is stable at low to medium temperatures, but polymerizes when the temperature exceeds 125°C to form polydioxolane with a consequent rapid rise in the internal resistance of the cell. This provides an internal shut-off safety mechanism which, combined with a built-in vent,... 

Larger button cells with rated capacities in the range 35-lOOOmAh are manufactured for direct mounting on printed circuit boards where they are used as standby power sources for CMOS RAMs, reference voltage sources, etc. Fig. 9.10 shows the construction of these cells and the position of the terminal/mounting pins. Projected discharge curves for Catalyst Research Corporation cells are given in Fig. 9.11. 

Ni-Cd batteries can be used at a wide range of temperatures (—40° to +50°C). Fig. 3B shows a family of discharge curves at various temperatures for sealed Ni-Cd batteries. As shown in the plot, both capacity and average voltage decrease with decreasing temperatures. At -20°C, about 80% of the rated capacity can be obtained at 0.2 C rate. 

The battery capacity represents the electric charge that a battery can supply. Instead of using the Coulomb, which is the SI unit for the electric capacity but is an inconveniently small unit, the Amphour (Ah) is commonly used to refer to the capacity of electric vehicle batteries. Batteries are characterized by a nominal value of capacity, determined with predefined procedures. However, the real capacity of a battery depends on the current values drawn out from it. This changing in the expected capacity is caused by uncompleted or unwanted reactions inside the cell. This effect occurs in all the types of batteries, but it is particularly accentuated for lead-acid batteries. Figure 5.13 shows typical discharge curves for different discharge rates (/j, where the black line shows the available... 

From such data, the capacity is calculated from the product of I (the discharge current) and t (the time required for the battery voltage to decrease to a value of below which the battery is no longer useful). The flatness of the discharge curve and the ability of the battery to deliver its expected capacity at increasing currents (i.e., discharge rates) are important battery properties. The real capacity of a battery is usually well below its theoretical value. 

Capacity curves—volume, discharge pressure, power required as per purchase order Depth of submergence—for submerged pumps Discharge pressure (rated)... 

Sulfnr temperature to which the pump was subjected Capacity curves—volume (mVh), discharge pressure (rated), power required Depth of submergence—for snbmerged pumps Electrical load (kW)... 

In most pumps, the speed is generally not varied. Characteristic curves for a typical single-stage centrifugal pump operating at a constant speed are given in Fig. 3.3-2. Most pumps are usually rated on the basis of head and capacity at the point of peak efficiency. The efficiency reaches a peak at about 50 gal/min flow rate. As the discharge rate in gal/min increases, the developed head drops. The brake hp increases, as expected, with flow rate. 

Figure 4.11 Characteristic curves (pump head, effective capacity and efficiency subject to the discharge rate) of a rotary pump from KSB.

Note The factor m has no relation to discharge time m is a pure number. For this reason, discharge rates in terms of multiples of the capacity cannot he converted into discharge duration. To evaluate the discharge duration, the discharge curves must be known. 

FIGURE 10.8 Typical constant-cutrent discharge curves at 20°C for an AA-size alkaline-manganese dioxide battery voltage vs. percent of capacity at various discharge rates. (Courtesy of Duracell, Inc.)... 

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