Operating voltage
>> Working voltage.

Organic material
Part of the expander in negative paste. Usually of ligneous nature.

Over-discharge
>> Deep discharge.

Overcharging
Charging beyond the fully loaded stage. This can result in battery damage (loss of electrolyte).

Overcharging current
Current which flows in the fully charged battery when the gassing voltage is applied (e.g. 2.4 V per cell at 25°C for the lead acid battery). It results in capacity
maintenance and water loss.

Oxidation
Release of electrons through the cells active mass to the external electric circuit. During the discharging process, cadmium is oxidised at the negative electrode
of the nickel-cadmium cell or sponge lead is oxidised at the negative electrode of the lead cell.

Oxide (of lead)
>> Lead oxide.

Oxide mill
>> Lead oxide mill.

Oxy-hydrogen gas
Gaseous mixture of hydrogen and oxygen (H2O2 mix) which is extremely flammable over a wide composition range. Oxy-hydrogen gas is created when
overcharging battery systems with hydrous electrolyte.

Oxygen evolution
Gaseous oxygen is reduced from the electrolysis of water when a battery at the charging stage reaches a certain voltage. >> Gas formation.

Oxygen recombination
Electrochemical process in which oxygen is produced at the negative electrode with the formation of water. >> Maintenance-free battery with fixed electrolyte.
Part of the expander in negative paste. Usually of ligneous nature.