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
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