accumulator

The lead–acid car battery is a typical example of an accumulator. The battery has a set of grids immersed in a sulphuric acid electrolyte. One set of grids is made of lead (Pb) and acts as the anode and the other set made of lead oxide (PbO₂) acts as the cathode.

In electricity, a storage battery – that is, a group of rechargeable secondary cells. A familiar example is the lead–acid car battery.

An ordinary 12-volt car battery consists of six lead–acid cells which are continually recharged when the motor is running by the car's alternator or dynamo. It has electrodes of lead and lead oxide in an electrolyte of sulphuric acid. Another common type of accumulator is the ‘nife’ or NiFe cell, which has electrodes of nickel and iron in a potassium hydroxide electrolyte.

The current that can be obtained from a cell depends on the active area of the plates in contact with the electrolyte. If more current is required than can be obtained from one cell, several cells are connected in parallel. Batteries are usually charged on about 2.7 volts per cell, and charging is continued until each cell reaches its specified voltage and the electrolyte its normal relative density (1.2–1.3), these values being maintained when the charging is discontinued. Tests are made with a portable voltmeter and a hydrometer. An indication that the charge is nearly completed is given by the ‘gassing’, the escape of excess hydrogen and oxygen, resulting from decomposition of the water.

accumulator

In computing, a special register, or memory location, in the arithmetic and logic unit of the computer processor. It is used to hold the result of a calculation temporarily or to store data that is being transferred.

accumulator

Collective bet, usually on horse races (normally four or more), such that the winnings from one race are carried forward as the stake on the next, resulting in a potentially enormous return for a small initial outlay.

accumulator

Device to store hydraulic pressure energy. It permits a small pumping station or installation to be installed where the hydraulic machinery, such as cranes, dock gates, lifts, and forging presses, has only intermittent power draw. The presence of an accumulator in a hydraulic system acts as a convenient store of energy.

Accumulators may be weight-, spring-, or gas-pressure-loaded. Weight-loaded types are no longer used and spring-loaded types are now virtually confined to small mobile machinery. In gas-pressure-loaded types the hydraulic fluid may be in direct contact with the gas, or separated from it by a rubber or neoprene diaphragm or bag, or by a floating piston.

The hydraulic accumulator was invented in 1851. A pump raised a ram loaded with heavy weights, and the release of the ram provided the power to work machinery.