ABSTRACT
Since the maintenance-free sealed nickel/cadmium accumulator became of high importance in the market, in the middle of the 1950s (Figure 17.1), the German battery company Sonnenschein has invented the first maintenance-free portable lead-acid batteries in small sizes in modules of 2 to 12 V between 1 and about 30 Ah. These batteries have been absolutely maintenance free and because of their immobilized electrolyte they could be used in any position without leakage. Applications for these batteries were electronic flashlights, portable TVs, tape recorders, and electric lawn mowers. Also for emergency power supply and in alarm equipment these batteries in valve-regulated construction are used still today.
