During 1977 to 1979, Magneti Marelli decided to develop an in-house expanded-metal grid technology. The metallurgy of lead-calcium alloys for strip production was investigated extensively and a continuous system was developed. Production problems were solved with machinery of proprietary design and in 1979 about a hundred thousand Fiat cars were equipped with hybrid batteries. After about three years of labour and field tests on the integral use of lead-calcium-tin expanded grids, it was decided to convert the whole production (about 3 million batteries/year) to this technology.