Negative grid

Automobile battery grids employ about 1—3 wt % antimony—lead alloys. Hybrid batteries use low (1.6—2.5 wt %) alloys for the positive grids and nonantimony alloys for the negative grids to give reduced or no water loss. The posts and straps of virtually all lead—acid batteries are made of alloys containing about 3 wt % antimony. 

We discuss two situations, for negative grid bias first and for positive grid bias next. 

Below we define fx as the amplification factor, which depends on the geometry of the tube and not on either Ec or E/,. If (Ec I Eb//x)>0, then the plate current under forward bias and negative grid bias is given by... 

OCSM cells with tubular positive plates and copper negative grids have been used successfully for various stationary applications. In 1986, for example, a... 

Grid casting. Lead alloys are used for casting the positive and negative grids, as well as for small structural components (e.g., post straps, coimectors, terminal posts). Highly automated and efficient casting machines are used. 

As a rule, national battery standards stipulate only Pb purity grade of 99.99% without specifying the type and amount of allowable impurities. The specific infiuence of additives to and impurities in lead alloys has been in the focus of attention of many researchers [6—12]. Table 4.3 summarises tbe maximum allowable impurity levels for both primary and secondary lead for battery use [10]. Secondary lead comes from recycling batteries after purification. Lead of the purity grade presented in Table 4.3 can be used for the manufacture of leady oxide and lead alloys for both positive and negative grids. 

Low-calcium alloys (with 0.02—0.04 wt% Ca content), used for casting negative grids for standby batteries intended for float service. Very small amounts of aluminium are usually added to these alloys. 

High-calcium alloys (0.10—0.15 wt% Ca). They contain high levels of aluminium as well and are used for casting negative grids for automotive batteries. 

This technique was first used only for the manufacture of negative grids because expanded positive grids suffered from severe corrosion. However, with the improvement of the rolling... 

As is illustrated in Fig. 5.15, a DC load line is applied to the pentode plate characteristics in the same manner as for the triode. In the example shown, Rl = 1 and the Q-point values are Vp = 300 V, Ip = 200 mA, Vg —9 V. Note for this device that positive-grid operation is possible and that nonhnearities occur for large negative grid voltage because the curves are not evenly spaced. An AC load is added to the pentode plate characteristics in the same manner as for the triode case, and the graphical analysis proceeds in the same manner as for the triode. 

FIGURE 5.159 Internal construction of typical motive power cell. Key 1, terminal post 2, positive grid 3, vent cap 4, cover 5, acid level indicator 6, separator protector 7, negative grid 8, active material 9, positive active material retention material 10, positive active material retention material 11, positive active material retention material 12, separator 13, container or jar 14, positive active material retention material 15, plate rest and sediment area. 

Dielectric systems usually employ negative grid triode tubes, although some systems operating in the 50 to 100-MHz range use beamed power types. RF circuits are usually simple, self-excited oscillators of the Hartley, Colpitts, or tuned plate-tuned grid type. These circuits usually consist of coils and capacitors or coaxial lines. The load to be heated may actually form part of the tank circuit capacitance, it may be separately tuned or inductively or capacitively coupled to the oscillator, or it may be a combination of these, which is directly connected to the oscillator and also... 

---