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by Bob Mills (from January 1995 and May 1995 Newsletters)

A Little History

Today we tend to take batteries for granted. They are cheap, relatively clean and reliable. Yet it was not always so. Many were the hours spent by learned men in the 19th century trying to devise the perfect power source. Here is a little about their efforts.

These batteries were used for the purpose of powering early telegraph and telephone equipment and for many other applications such as lightning and laboratory work in which only comparatively small currents of electricity were required. The following refers to cells, and a number of cells were connected together to form a battery.

A galvanic or Voltaic cell consists essentially of two different metals immersed in some substance, generally a liquid, composed of two or more chemical elements, one at least of which tends to combine with one or other of the two metals, or with one more than the other.

A very simple form of cell consists of a plate of zinc and a plate of copper (these plates are known as electrodes) partly immersed in sulphuric acid (known as the electrolyte). It will generally be found, even if there is no connection between the zinc and the copper except through the acid, that the zinc will dissolve slowly giving of bubbles of gas. If a connection is made between the zinc and the copperthen this action will be found to increase considerably. Oxygen is given off from the zinc plate and hydrogen from the copper plate. After a short time the voltage available from the cell will drop and it will be observed that the copper plate is coated with small bubbles of gas. This phenomenon is known as polarisation and much of the design effort expended in early cell design was to diminish the effects of this polarisation. And many materials and methods were tried.......

Voltiac Pile

About the year 1780, Galvani, Professor of Anatomy at Bologna in Italy, observed that dead frogs, hung on an iron balcony by means of copper hooks, twitched whenever the wind brought their legs in contact with the iron.

Around 1799, Volta, Professor of Physics in the University of Pavia in Italy, investigated the effects on the frogs and demonstrated that the seat of the electrical energy lay in the contact of the two dissimilar metals. From these experiments he constructed the Voltiac Pile consisting of discs of copper and zinc separated with wet cloth or blotting paper moisened with brine.

Following Volta's discovery, the first simple copper-zinc-acid cell made its appearance in 1800 at the hand of William cruickshank. A few years later, in 1808, Pepys, son of an English surgical instrument maker, constructed an enormous battery of 2,000 plates with a total area of 128,000 square inches. Several improvements were made to containers and devices for raising plates out of the cell when not in use. Then came Wollaston who greatly improved efficiency by exposing both sides of the zinc to the action.

In 1822, Pepys was again noted for his large spiral cell which produced great heat and was named a calorimotor. It used strips of copper and zinc two feet wide and fifty feet long, laid together with horsehair and rope separators around a wooden cylinder. All cells of the time suffered from the effects of local action, the eating away of the zinc plate, and, of course, of polarisation.

The early 1820's saw interest in further development waning as John Bostock, noted English physician, stated, in effect, that science had gone about as far as it could go in improving the electric cell.

Bostock was wrong, of course, and 1828 saw Kemp and Sturgeon devise a method of minimising local action by rubbing the plate with mercury on an acid impregnated rag. Polarisation was not so easy and many experimented including Becquerel in 1829. But the first practical self depolarising cell came in 1836 from professor Daniell.

The Daniell Cell

There is not a better primary battery for telegraph working tha the Daniell cell or one of the variations on the basic design. The cell consists of a rectangular chamber of ebonite or porcelain into which is placed an earthenware porous pot containing a copper plate, whilst the zinc plate is placed in the chamber outside the porous pot. The chamber is the filled with dilute sulphuric acid. The one drawback is the tendency of the copper solutions to mix through the porous pot and deposit on the zinc electrode.Voltage - about 1.07 volts, weight - about 3 pounds. The Daniell cell is often made up into a battery for telegraph work and one standard formatconsisted of 10 cells in a wooden box measuring 30" x 7" x 7" with a total weight of 36 pounds.

The Grove Cell

This cell was devised by Mr Justice Grove in 1839 and consists of an external vessel made in a rectangular form in glazed earthenware or glass and contains a thick plate of amalgamated zinc, bent upwards and between the two portions, a flat porous cell is placed filled with strong nitric acis, in which is immersed a thin sheet of platinum. This platinum plate must be washed in water periodically to remove absorbed nitric acid. The outside vessel is charged with water mixed with 1/8th sulphuric acid. Gives off nitrous oxide in use. The grove cell is shown in cross section ond complete.

The Bunsen Cell

This type is similar to the Grove cell except that the platinum is replaced with coke (carbon). The vessel can be either rectangular or circular. Provides strong currents for short periods but the carbons must be soaked in water for some hours to remove the nitric acid that has been absorbed. Gives off nitrous oxide in use.

The Smee Cell

Smee experimented around 1840 with the typical copper and zinc cell and devised a design which differed from the original only in the fact that the copper plates were replaced with plates of silver covered with a coat of platinum in a very fine state of division. These plates give off bubbles very freely but still the remedy was only a partial one as the voltage of this cell is found to fall considerably after it has been in action for a few minutes.

The Poggendorff Cell

A most efficient means of overcoming polarisation is to employ, as a liquid surrounding the plate at which hydrogen is set free, a solution containing some highly oxidising substance. This could not be achieved in a typical copper/zinc cell and so Poggendorff devised the "Bichromate" cell consisting of plates of carbon and zinc immersed in a solution of bichromate of potash to which a small quantity of sulphuric acid is added. The disadvantage is that the solution begins to dessolve the zinc as soon as the circuit is broken, and therefore arrangements have to be made for lifting the zinc plate out of the solution when not in use. One use of this cell was to power a bedside light to read the time and required that the plate be pressed down into the cell to start the light and return out of the cell by spring action when the pressure was released.

Siemens and Halske Cell

This is a form of Daniell cell with an improved porous diaphragm which diminishes the local action and increases its efficiency. The cell consists of s glass jar containing a bell-shaped porous cup with a glass tube cemented into it. A diaphragm of paper-pulp surrounds the porous vessel within which stands the copper electrode. The zinc electrode rests on the paper pulp. The bell-shaped vessel is charged with crystals of copper sulphate and the glass jar contains dilute sulphuric acid. The paper pulp prevents these two solutions from mixing. Voltage - about 1 volt, weight - about 3 1/2 pounds.

The Gravity Cell

Variation on the Daniell cell which makes use of the different specific gravity of various solutions to remain separated when together in a vessel. In this cell a copper element, made up of riveted strips, is fixed at the bottom of the glass jar. The jar is then partly filled with a saturated solution of sulphate of copper, to which extra crystals are added. Over this a weak solution of sulphate of zinc is carefully poured so as not to mix. Into the zinc solution a "crowfoot" shaped zinc plate is hung over the edge of the jar. Vibration must be avoided to prevent the solutions mixing and the specific gravity of both solutions must be checked regularly.

The Calland Cell

This is another version of the Daniell cell and consists of a glass jar from the rim of which is suspended a split cylindrical ring of zinc forming the negative pole of the cell. the positive pole consists of a strip of sheet copper bent into a cylinder and riveted to a copper wire covered with gutta-percha insulation (the diagram shows the positive plate connected so as to go to the next cell in a battery). The jar is filled with water containing one tenth part of saturated sulphate of zinc. Crystals of sulphate of copper are dropped into the jar until they cover the copper cylinder.

The Fuller Cell

This type of cell was adapted by the Bell Companies in the USA as their "standard" cell for long distance work. It comprises a glass jar with a positive electrode of a heavy block of zinc moulded into a conical form. The negative electrode is a block of carbon hanging through a slot in the wooden cover. The elecrolye is dilute sulphuric acid with sodium bichromate added. A Fuller cell able to deliver 8 amps at 2.1 volts would weigh 8 3/4 pounds.

The Gordon Cell

Sometimes used for central battery exchange working, the Gordon cell consists of a porcelain vessel in which is placed a perforated steel cylinder with a bottle shaped lining, also perforated. On the outside of this is placed three porcelain lugs which support a wide ring of zinc. The space between the steel cylinder is filled with a depolariser made up of small lumps of black oxide of copper. This is surrounded by an exciting fluid of a 30% solution of caustic soda and to prevent evaporation, a heavy solution of petroleum is poured over the excitant. Voltage - about 0.84 volt.

Minotto Cell

Another variation of the Daniell cell used extensively in India for telegraph work. Consists of a cylindrical glass jar with a disc of copper <I>(to which is rivetted a connecting wire)</i> at the bottom of the jar, a layer of crystals of copper sulphate above the disc, then a layer of blotting paper or cloth, followed by a thick layer of saw dust or clean river sand, another thickness of blotting paper and finally a disc of zinc with a column supporting the terminal. The vessel is then filled with water to a level just above the zinc.

Edison-Leland or Laland-Chaperon Cell

One of the most successful cells for the production of relatively high currents. Invented by leland and modified by many others including Edison who released the Edison-Leland cell. Consists of a cylindrical glass vessel containing an alkaline electrode of caustic potash. From the porcelain cover of the vessel is suspended a central plate of zinc and two blocks of compressed finely ground copper oxide, one on either side of the zinc. A layer of petroleum is sometimes included to prevent evaporation. When the cell delivers current, potassium zincate is formed and the copper oxide is reduced to metallic copper.

Leclanche Cell

The most popular cell for telephone work and has stood the test of time, today's dry cells being variations on this design. A glass jar contains a cylindrical rod of zinc as the negative plate whilst the positive is a block or rod of carbon contained in a porous pot containing manganese di-oxide as a depolariser. The glass vessel is then filled with a solution of sal-ammoniac.

In the most common form the space inside the porous pot is packed tightly around the carbon rod with granulated manganese di-oxide and carbon, the top is then sealed with a small opening for escaping gases <I>(standard cell shown left)</i>. In the agglomerate pattern, the carbon plate is held between two blocks, formed under great pressure, of a mixture of manganese di-oxide and carbon.

The Dry Cell

The dry cell is dry only in the sense that it does not spill. The chemical action, and the chemicals used, do not differ materially from those of the Leclanche battery. Dry cells in practical use from the 1920's were nearly all some form of sal-ammoniac cell with the zinc made into the form of a containing jar. The top is sealed over to prevent evaporation and the electrolyte is all taken up by an absorbent so that there is no liquid to spill even before the top is sealed over.

The Gassner Cell

This is one of the earliest dry cells to be made and consists of a thin zinc sheet case and can be found in a number of shapes. The zinc case is the negative element and was nearly filled with zinc oxide and gypsum made into a paste with a zinc chloride solution. The positive element in the centre was a capped carbon rod bearing a binding screw. The contents of the cell are sealed over with a composition resembling marine glue.

The Lessing Cell

Another early cell, the lessing has an outer vessel made of porcelain immediately inside which is a sheet zinc cylinder in one piece with a strip running upwards to the negative binding screw. The cylinder and strip are made in one piece to avoid local action at the rivet or solder point where the two would join. The positive plate is a flat carbon surrounded by manganese di-oxide contained in a canvas bag bound with thread. The electrolyte is sal-ammoniac thickened with flour and this occupies the space between the bag and the zinc. Above this is a layer of sawdust and the cell is capped with a bituminous seal through which passes a lead vent tube. (A section of the Lessing Cell is shown at right

The ECC or Burnley Cell

In the early form of the EDD cell the outer case is insulated at the bottom by a millboard case. In the later cells, the millboard covers the whole of the zinc case. The positive carbon rod is surrounded by a paste of manganese peroxide and powdered carbon moistened with a solution of sal-ammoniac and zinc chloride. This is in turn surrounded with a paste of plaster of Paris and flour moistened as before. The whole is sealed with bitumen through which passes a vent tube. Improved forms of this cell are made up with millboard insulating cylinders waxed on the inside where a special method of sealing is employed. In these later cells the capacity has been greatly increased.

Obach Cell

In this form of early dry cell, the zinc is in the form of a pot which contains the other elements. The positive element consists of a carbon rod surrounded by a depolariser composed of a mixture of peroxide of manganese and carbon, both in a pulverised condition. the electrolyte is sal-ammoniac which, in solution, is mixed with flour and plaster of Paris to form a paste. The space at the top of the cell is filled with sawdust and sealed with bitumen through which pass two glass vent tubes. Terminals are attached to the zinc and carbon and the cell is usually enclosed in a cardboard box.

The Hellesen Cell

Again in this cell the zinc element is a cylinder and the positive is a carbon rod surrounded with a depolariser. The depolariser is composed of pulverised peroxide of manganese and carbon and is wrapped in thin textile and bound with string. The electrolyte is sal-ammoniac mixed in solution with plaster of Paris and flour to form a paste which surrounds the carbon rod. The top of the cell is filled with sawdust or slag wool over which is placed plaster of paris. The top is sealed with bitumen.

Modern Dry Cells

Modern general purpose dry cells as used in torches and toys are similar in construction to the dry cells of old. A zinc can forms the negative side of the battery and contains a carbon rod which forms the positive pole. Around this rod is a mixture of manganese di-oxide and carbon powder and between this mixture and the zinc can is the electrolyte made of a paste of ammonium chloride, zinc chloride and water.

Alkaline cells are similar in construction to carbon-cells as described above however there are some differences. The zinc can is made of highly porous material that oxidises more readily. The electrolyte is potassium hydroxide which conducts electricity more readily and allows the cell to deliver higher currents for longer periods.

The humble primary cell has been serving man for many years and will continue to do so for many years to come. Giant steps were made in the early days to improve the cells however, once the Leclanche cell was developed, little significant has been needed up to the present time to the basic design of the cell. Certainly much good work has gone into special purpose batteries but the common dry cell still remains much as it was 50 or 100 years ago.


"Modern Electric Practice", Vol I, by Magnus Maclean, 1910.

"The Practical telephone Handbook", by J Poole, 1912.

"Electric Primary batteries", by Bernard E. Jones, 1924.

"World Book Encyclopedia," Vol II, 1982.