spongy lead

lead peroxide

dilute sulphuric acid

all the above stated materials

keeping the battery idle for a long time

trickle charging

high rate discharging

high rate charging

nickel hydroxide

powdered iron and ferrous hydroxide

21% solution of caustic potash

all the above stated materials

its e.m.f. remains constant

water is neither formed nor absorbed

corrosive fumes are produced

nickel-hydroxide remains unsplit

equal to the battery nominal voltage

twice the battery nominal voltage

2.3 to 2.5 V per cell

half the nominal voltage of the battery