Tubular-plate batteries

Technological scheme for the manufacture of tubular-plate batteries. 

Figure 3.3 Depiction of thermal energy generated in 1 h in a tubular plate battery with different discharge currents.

A further selection criterion is provided by the different limit temperatures in the electrolyte, as is also depicted in Table 3.2. The use of a particular battery system becomes questionable when the ambient temperature approaches its maximum permissible temperature. Nickel/cadmium batteries have a significantly lower limit temperature than lead-acid batteries. The systems thus dictate that lead-acid batteries should exclusively be used when the ambient temperature exceeds 35 °C to 40 °C. In the case of extreme ambient temperatures, however, a renewal of batteries should also be planned for, in order not to jeopardize the long service life typical of the system, even when using tubular plate batteries. 

FIGURE 23.29 Effect of discharge rate on capacity of traction batteries at 25°C. Comparison of performance of flat-pasted-plate vs. tubular-plate batteries. 

In Figure 1, the cutaway view of the automotive battery shows the components used in its constmction. An industrial motive power battery, shown in Figure 2 (2), is the type used for lift tmcks, trains, and mine haulage. Both types of batteries have the standard free electrolyte systems and operate only in the vertical position. Although a tubular positive lead—acid battery is shown for industrial appHcations, the dat plate battery constmction (Fig. 1) is also used in a comparable size. 

Fig. 2. Cutaway view of a tubular positive lead—acid battery, (1) Positive tubular plate (2) iiegatwe plate (3) separator (4) connecting strap (5) ceU cover (6)...

The tubular positive plate uses rigid, porous fiber glass tubes covered with a perforated plastic foil as the active material retainer (Fig. 2). Dry lead oxide, PbO, and red lead, Pb O, are typically shaken into the tubes which are threaded over the grid spines. The open end is then sealed by a polyethylene bar. Patents describe a procedure for making a type of tube for the tubular positive plate (90) and a method for filling tubular plates of lead—acid batteries (91). Tubular positive plates are pickled by soaking in a sulfate solution and are then cured. Some proceed directiy to formation and do not requite the curing procedure. 

The tubular-plate design for the positive electrodes, shown in Fig. 7, is common mainly in European countries for batteries with larger capacities. In this plate design, the conducting elements are separated... 

Purpose-built batteries. Gel batteries with either tubular plates or thick, flat plates (> 5 mm) are recommended when a long cycle-life is required. Both designs have a high level of resistance to positive-plate degradation, and can tolerate high levels of positive-grid corrosion. 

Many manufacturers around the world offer tubular-plate gel batteries for heavy-duty RAPS operations. As the name suggests, the batteries have tubes that contain the plate material. This design is employed only for the positive plates, as these are... 

The tubular-plate technology is used in the manufacture of traction and stationary batteries. Figure 2.53 shows die main stages involved in the classical production process of mbular plates. Only the preparation of positive plates will be described briefly, since the other technological stages are identical to those discussed for flat-plate batteries. 

Antimony alloys 4—11 wt% Sb, As, Sn, Cu (Ag) Flat plates, tubular plates for traction batteries, older types of stationary batteries... 

Figure 4.39 presents a micrograph of the CL formed on the spines of tubular plates cast from Pb—0.09 wt% Ca—0.3 wt% Sn alloy (r = 3.33) [18]. The battery suffered from PCL-1 effect and had low capacity. The picture features a thick CL wifli cracks parallel to the spine surface, which impair the contact CL PAM. The appearance of these cracks can be attributed to the low creep resistance (30 h at 20.7 MPa). This is a value lower by more than a magnitude than the highest creep resistance measured for Pb—Ca—Sn alloys. The micrograph in Fig. 4.39... 

Tubular plates are used mainly for high-capacity long-cycle-life batteries. The latter find application in industrial in-house transport vehicles (forklifts, electric cars, etc.) as well as for... 

Tubular plates offer several advantages over the flat-plate grid design, flie most important of which is that they prevent shedding of the PAM during battery service as it is held within the tubes. Thus, a lower density of the active material can be used. The typical active mass density for tubular plates is 3.6—4.0 g cm (cf. 4.0—4.3 g cm for flat-pasted plates). In addition, the enhanced porosity of the tubular plates improves the active mass utilization coefficient. 

Figure 4.64 shows the specific capacity of the PAM vs discharge current density for batteries with three types of plates SGTP, SLI and cylindrical tubular plates [103]. Batteries with SGTP... 

Cross section geometry of four types of tubular plates (a) cylindrical (round), (b) elliptical (oval), (c) square and (d) rectangular. Cylindrical and elliptical tubular plates are used for flooded batteries, whereas square and rectangular designs are preferred forVRLA batteries with ACM separators. 

Most often, high percentage (65 wt%) red lead and leady oxide blends are used for filling positive tubular plates for bofli traction and stationary batteries. 

Leady oxide manufacture is potentially very hazardous. It is therefore vital to take adequate measures to minimise, or even eliminate altogether, possible lead dust emissions out to the working environment and thus exposure of the personnel which would cause health problems. This is achieved by the use of a closed (isolated) leady oxide production equipment and transport pipes from the storage silos to the paste mixing unit. Special attention should be paid to file manufacture of tubular battery plates. Until recently, tubular plates were filled with a dry mixture of leady oxide and red lead powders. 

Lead-battery electrodes can be made as a flat plate with a lead grid as the current collector or as a tubular plate design with a lead rod current collector in the center of tubes. Monopolar electrode current collectors have a conductive lead grid that connects with the terminal. The current collector physically supports the electrode and also collects and carries the current to the electrical system. 

Tubular batteries have flat negative plates opposing the positive tubular plates. Recent approaches to preventing positive plate shedding with improved separator designs have limited the use of tubular positive plate batteries. They are primarily in applications that have deep-discharges or severe vibration. 

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