Traction lead acid cells

Each standard needs an update following the technical development. So when the new international standard for dimensions of traction lead-acid cells lEC 60 254-2 was published and harmonized in the European Union to a European standard EN 60 254-1, DIN 43 595 was drawn back. In an additional technical information sheet, published by the German Battery Manufacturers Association, the (nominal) capacities in use were listed in relation to the cell dimensions. Table 2.3 shows the range of cell heights conforming to lEC (respective EN 60 254-2) together with the new series of higher capacities. 

Figure 12.3 Charging time for lead acid and NiCd batteries. (A) Rectifier nominal current for charging traction lead acid cells GiS and PzS at 20°C (68°F) after discharge of (a) 80% and (b) 100% of C5. (B) Rectifier nominal current for charging of stationary lead acid cells OPzS, Gro, GroE at 20°C per 100 Ah K5 after discharge of (a) 80% and (b) 100% of C5 (operation conforming to DIN 40729). (C) Rectifier nominal current for charging R, TN/TS, and F type cells at 20°C per 100 Ah C5 after discharge of (a) 80% and (b) 100% of C5 (operation conforming to DIN 40729).

By far the largest sector of the battery industry worldwide is based on the lead-acid aqueous cell whose dominance is due to a combination of low cost, versatility and the excellent reversibility of the electrochemical system, Lead-acid cells have extensive use both as portable power sources for vehicle service and traction, and in stationary applications ranging from small emergency supplies to load levelling systems. In terms of sales, the lead-acid battery occupies over 50% of the entire primary and secondary market, with an estimated value of 100 billion per annum before retail mark-up. 

The most important market remains the car battery for starting, lighting and ignition (SLI), with approximately 50 x 10 units per year being sold in the USA. Lead/acid batteries are, however, also used on a very large scale for traction (e.g. delivery vans, milk floats, fork-lift trucks, industrial trucks — there are more than 100 000 such vehicles in the UK) and for stationary back-up or emergency power supplies. More recently, small lead/acid cells to compete with high-quality primary cells and nickel/cadmium cells for instruments, radios, etc., have also become available. 

Typical dimensions for the /5-alumina electrolyte tube are 380 mm long, with an outer diameter of 28 mm, and a wall thickness of 1.5 mm. A typical battery for automotive power might contain 980 of such cells (20 modules each of 49 cells) and have an open-circuit voltage of lOOV. Capacity exceeds. 50 kWh. The cells operate at an optimum temperature of 300-350°C (to ensure that the sodium polysulfides remain molten and that the /5-alumina solid electrolyte has an adequate Na" " ion conductivity). This means that the cells must be thermally insulated to reduce wasteful loss of heat atjd to maintain the electrodes molten even when not in operation. Such a system is about one-fifth of the weight of an equivalent lead-acid traction battery and has a similar life ( 1000 cycles). 

The world market for batteries of all types now exceeds 100 billion. Over half of this sum is accounted for by lead-acid batteries - mainly for vehicle starting, lighting and ignition (SL1), and industrial use including traction and standby power, with about one-third being devoted to primary cells and the remainder to alkaline rechargeable and specialist batteries. 

The manufacture of secondary batteries based on aqueous electrolytes forms a major part of the world electrochemical industry. Of this sector, the lead-acid system (and in particular SLI power sources), as described in the last chapter, is by far the most important component, but secondary alkaline cells form a significant and distinct commercial market. They are more expensive, but are particularly suited for consumer products which have relatively low capacity requirements. They are also used where good low temperature characteristics, robustness and low maintenance are important, such as in aircraft applications. Until recently the secondary alkaline industry has been dominated by the cadmium-nickel oxide ( nickel-cadmium ) cell, but two new systems are making major inroads, and may eventually displace the cadmium-nickel oxide cell - at least in the sealed cell market. These are the so-called nickel-metal hydride cell and the rechargeable zinc-manganese dioxide cell. There are also a group of important but more specialized alkaline cell systems which are in use or are under further development for traction, submarine and other applications. 

Different types of lead-acid batteries have been developed as energy sources for many power applications, like traction and backup or standby power systems. The flooded lead-acid batteries have an excess or flooded electrolyte and they were the largest used at the beginning of the last century for many applications. Valve-regulated lead-acid (VRLA) batteries were developed as an alternative to the flooded lead-acid batteries, in order to maintain levels of distilled water and prevent drying of cells, which means safe operation for battery packs in electric... 

The overall dimensions of these tubular plate-type cells also accord to the lEC Standard 60 254-2, Lead-acid traction batteries, part 2, cell dimensions for traction batteries . 

Table 2.4 Lead acid traction cells with tubular plates, series L, dimensions conforming to lEC 60 254 2. 

Nominal capacity after 10 discharges electrolyte density 1.28 + 0.01 kg/L electrolyte temperature 25 °C. Table 2.7 Lead-acid traction batteries in plastic trays with single cells and positive tubular plates (DIN 43 598 part 2). ... 

Figure 2.6 shows the specific drawable energy of lead-acid traction batteries of different designs. The lower graph represents the capacity of the common PzS cells. Further development of this cell type for application in electric road vehicles of the PzF type yields accordingly higher values. 

A further possibility to increase the performance of lead-acid traction cells is electrolyte circulation, as proved in batteries for electric road vehicles and batteries for submarines. The principle is an airlift pump installed in each cell. The results are... 

Figure 2.10 shows a modern lead-acid traction cell designed by Varta with electrolyte circulation compared to a cell with electrolyte stratification. There are many electrochemical systems that will yield favorable accumulators (see Chapters 1 and 10), some of which have reached a very promising state of development. They will have to prove their versatility in practical application, especially with the aspect of economy in the future. 

Figure 4.9 Development of energy density (percent Wh/kg) of lead acid traction cells with future outlook.

ZVEI has created a diagram (Figure 5.3) to determine the expected service life of a lead-acid traction battery with positive tubular plates this diagram is a good basis for calculation, but it has to be noted that this diagram is only applicable for cells with a liquid electrolyte. For other cell types, e.g., the VRLA types, the diagram cannot be used. 

Testing standards include testing methods for type and acceptance tests. Example DIN 43539, part 3 titled Lead-acid accumulators test methods, traction cells and batteries. ... 

DIN 43 537 Lead-acid accumulators traction batteries for road-bound electric vehicles, cells of low maintenance type Nominal capacities, main dimensions. 

DIN 43 539, Part 3 Lead-acid accumulators Test methods, traction cells and batteries. Harmonized (see EN 60 254-1). 

The lead-acid battery system is by far the least costly of the secondary batteries, particularly the SLI type. The lead-acid traction and stationary batteries, having more expensive constmctional features and not as broad a production base, are several times more costly, but are still less expensive than the other secondary batteries. The nickel-cadmium and the rechargeable zinc/manganese dioxide batteries are next lowest in cost, followed by the nickel/metal hydride battery. The cost is very dependent on the cell size or capacity, the smaller button cells being considerably more expensive than the larger cylindrical and prismatic cells. The nickel-iron battery is more expensive and, for this reason among others, lost out to the less expensive battery system. 

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