Plantd cells

Because of the high initial cost of Plantd cells, specially designed flat plate cells have been developed to provide a cheaper but shorter-lived alternative source of standby power. The layout of a typical modem flat plate cell is shown in Figure 32.2. 

Tubular cells are ideal for any kind of application that requires frequent chai]ge/dischaige cycles. When on standby duty, they have a life expectancy of 10-12 years, compared to 5 years when powering an electric truck. They are less costly than Plantd cells, but fall in capacity as time goes on. 

A recharge voltage table for a Plantd cell is illustrated in Table 32.3. 

Batteries for stationary applications may use cells with flat-pasted, tubular, Plantd, or Manchester positive plates. Typical discharge curves for the flat-pasted-type stationary cell at various discharge rates at 25°C are shown in Fig. 23.38, and the effect of the discharge rate on the capacity of the cell is summarized in Fig. 23.39. Generally, the discharge rate for stationary ceUs is identified as the hourly rate (the current in Amperes that the battery will deUver or the rate hours) rather than the C rate used for other types of batteries. 

Stationary batteries, like traction batteries, are available in a variety of plate and cell sizes. Stationary battery systems are assembled on insulated metal racks with groups of cells in series, having nominal system voltages of between 12 and 160 V. Some battery installations are made with several such series cell strings connected in parallel for greater storage capacity. Most stationary batteries in the United States are made with pasted positive plates. In Europe, Plantd and tubular positives are more popular. 

This type of cell is now gradually being replaced by a sealed ceU design, e.g. the Bell Telephone System and Western Electric Company Round Cell which contains saucer-shaped pure lead grids stacked horizontally. These cells have a life of about 30 years. Plantd type cells are still in use to some extent but... 

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