times of low power demand. Stationary batteries are also used for backup emergency power, telecommunications equipment, and uninterruptible power supplies. Stationary batteries are manufactured in a variety of plate designs. An example of a stationary battery used for backup power is shown in Figure 13.

Portable

Portable lead-acid batteries are usually of the sealed type constructed similarly to that depicted in Figure 14. Their operation cannot usually be described as cyclic or float, but is somewhere in-between. Batteries in this category may be frequently deep cycled or remain unused for a relatively long time. Typical applications are portable tools, toys, lighting and emergency lighting, radio equipment, and alarm systems. Most portable batteries may be recharged to 80–90% of their original capacity in less than an hour using a constant-voltage charger.

Vent plugs

Cell pillars and connectors

Cell lid

Negative plates (pasted grids)

Separators

(sintered microporous PVC)

Planté positive plates (constructed of pure lead)

Plastic container (transparent styrene acrylonitrile)

Figure 13. Typical stationary battery used for backup power.

Absorbent separator

Spirally wound cell Metal can

Polypropylene liner

Figure 14. Components of sealed lead-acid cell.