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A World First To Cap Them All

( Coal gold + base minerals of Southern Africa 1981)

This article written by C J Taylor A.R.I.C. Chlorides Technical Director takes an in-depth look at an important development in the cap lamp industry.  The article was sent to us by Colin Priddle (Pope) who lives in South Africa.

The South African mining industry is the largest user of cap lamps in the Western World.  Our mines requirements run to some 570,000 lamps - 3% of the western world total - while India is estimated to require 550,000 lamps and, there are some 850,000 in the other non-communist countries.  The Soviet Union and China between them are estimated to have some two million cap lamps in use.

The history of the cap lamp dates back to candles and subsequently the break-through of the Davy lamps which allowed naked flames for lighting without fear of methane fires. This was followed in the early 1930’s with the first electric miner’s lamp incorporating a battery encased in a metal cylinder worn on the miners belt.  It was not until 1950 that lead acid accumulators replaced the old alkaline battery and introduced for the first time the advantages of a self-service operation in the storage frames.

Since then, the mining industry has been growing at a fast clip world wide, but the miners cap lamp market has been relatively static.  Increased mechanisation and longer shifts offset what would otherwise have been a proportionate market growth.  This situation has now changed as the traditional miners cap lamp nears the end of its capacity for use in a rapidly changing mining industry.

Though the 1950-based cap lamps have served the industry well, certain disadvantages became of increasing importance in a rapidly developing mining industry which was gravitating towards longer shifts and deeper level mining.  These factors were particularly important in the South African mining sector following the boom in metal prices in the late seventies.  As new mining plans were announced the need for an advanced miners cap lamp led to a focus on the traditional products disadvantages. These were:

a)       Limited ampere-hour capacity which does not allow for longer shifts.

b)       Inadequate light output for industry’s future needs.

c)       The accumulators need constant topping up which means removing each filler plug for inspection.

d)       Charging time was considered too long as the industry moved towards longer shifts. A 1:1 charging to light availability ratio was regarded as Optimal.

e)       Liquid filled batteries incorporated a spill danger which caused minor accidents such as acid burns; and

f)        The mass of lamp unit was considered somewhat high in relation to output.

In order to meet the needs of the mining industry world wide and the South African market in particular, Chloride pursued the development of a new miners cap lamp and accumulator. The technological objectives of the research programme demanded a product that would incorporate:

a)       A maintenance free accumulator

b)       Shorter charging time.

c)       Higher ampere-hour capacity

d)       Improved light source and output!  and

e)       Reduced mass

Consequently, Chloride Technical in the UK, a subsidiary of the international Chloride Group, the worlds largest manufacturer of chargeable batteries, launched a two year development programme which resulted in the development of a maintenance-free accumulator and improved cap lamp.  In April 1980 the group placed some 200 of the new lighting units at Vaal Reefs and Doornfontein gold mines for testing which was monitored by the Chamber of Nines. The results surpassed the industry’s expectations and will result in full scale manufacture of the product later this year.

The new Chloride accumulator is the hub of the development.  Being maintenance free it should contribute to improved cost effectiveness while its power specification promises a much improved power: mass ratio, thereby fulfilling two of the major criticisms levelled at the traditional units.

In normal batteries oxygen and hydrogen are released from the electrolyte bring the charging process and this requires the units to be topped up with water.  However, Chlorides work on recombination technology has resulted in the manufacture of a battery which never needs to be refilled and thus can be completely sealed.  In fact though the battery is a lead acid type, the electrolyte is contained within the plates and the separators, so even in the event of damage to the battery case; there is no liquid to spill.  Thus, allied to maintenance free operation, Chlorides product should contribute to improved safety by avoiding minor accidents related to acid spilling.

Incorporated with the maintenance advantage the new mining accumulator is claimed to provide 61% more power, having a discharge cycle of 16 hours compared with 12 hours previously. At the same time the exterior casing has been cast in a plastic which showed nine times greater resistance to abrasion and impact than a hard rubber case.

This result should be particularly important in developing the export potential of the new miners lamp, as South African quartzites have in the past proved far more damaging to the battery cases than conditions pertaining in other parts of the world.






No. of Plates

Battery dimensions (mm)

Volume (m/)

Mass (filled with cover (kg)

Cycle Life


Container material


Duration (0.9A)

Operational voltage range (V)


3(2 negative 1 positive)

41 x 150 x 187



750 cycles (70% depth of discharge)

Resin Rubber


10 hours

4.00 to 3.70


3(3 negative 4 positive)

40 x 125 x 187



500-70 cycles (70% depth of discharge)

Abrasion resistant Rubber


16 hours

4.00 to 3.70

The, new accumulator is completely compatible with existing charging systems in the mining industry. But for full potential a new rack and charger has been developed which reduce the charge time through higher charge rating.  Incorporated in the accumulator is a fail safe feature in the form of an inner seal which allows gas to be released in the event of a serious over charge.

Though the significant breakthrough is in the development of. a maintenance free accumulator, Chloride has built into the unit certain other advances.  The plastic not only conforms to fire resistant specifications laid down by the mining industry, but is tamper proof and offers greater comfort to the user.  An integrated belt loop and the leak proof advantage make the unit more comfortable to wear, particularly in the narrow confines of a stope.  In addition the cable joining the accumulator and the battery has been redesigned with a new cable lock to prevent disconnection. Chlorides tests show that the cable lock can withstand forces of up to 670N at the headpiece and 1300N at the battery before becoming disengaged.

Allied to these efficiency and improved safety improvements the refined headpiece promises to fulfil the rest of the industry’s requirements.  In a mining environment the need for safety is paramount, and insufficient light at work stations contributes to minor accidents and a resulting fall in labour efficiency.  By incorporating a new-headpiece using a 4V 1A halogen bulb with a larger reflector, Chloride claims the new lamp boosts lumen output by six times.  (The introduction of a miniature halogen bulb is the result of extensive development by the major lighting companies in Europe and America).  Illumination at a distance of 2m is said to be 2klx, the greater energy needs being provided by the improved accumulator.

The impressive specifications of the new accumulator and headpiece have been sustained in local testing underground and have led to a very favourable reaction from a mining industry committed to enhanced safety and improved cost control.  In April last year 200 lamps were placed in both Vaal Reefs and Doornfontein and during the testing there was a notable decrease in the incidence of minor accidents.  In fact, the new product is probably technologically ahead of current mining industry needs, but should offer lighting to keep abreast of development in mining methods.

Though the maintenance free miners accumulator and improved cap lamp has a rival in new European nickel cadmium units, price and power capability suggest the lead acid system will be far more popular.  Not only does the maintenance free system offer significantly higher light availability, which makes it particularly suitable to South Africa’s longer shifts, but it is also priced some 7% lower.  This pricing difference stems from the cost of the metallic constituents in the NiCd Battery and the longer production runs possible in South Africa where 3% of the Free Worlds miners cap lamps are in use.


Not only will the launch of the maintenance free accumulator and improved headpiece be a world first for South Africa, but at the end of 1981 all components will be made locally. Initially the only imported component will be the halogen bulb, but plans are in hand to manufacture the item in South Africa.

In order to cater for local demands Chloride has invested some R1 million at its Benoni factory. Recently, Chloride SA managing director, Don Searle, said production would be geared to satisfying South African demand.  But as the South African Company will be the only Chloride operation worldwide manufacturing the new accumulator and headpiece export potential is huge.


The total cap lamp market outside the Soviet Union and China is estimated as 2 million units of which 570,000 – 30% are in South Africa and 550,000 in India.  This R50 million market includes export potential of around R35 million, in which the advantages of the long South African production runs and the manufacture of a product suited to arduous conditions locally should enhance sales potential of the Chloride development.  Thus, one local demand is satisfied the maintenance free development should allow South Africa its first major drive into a potentially huge export market.  Management is confident of success as the Chloride product is competitively priced.

The introduction of a world first maintenance free battery in the cap lamp market and the development of export potential could have far reaching effects in an industry constantly aware of the need for containing increases in mining costs.  Beyond that, the development could well pave the way to maintenance free, motive power batteries for underground and surface use which will help the industry in the constant battle to contain costs.


a)                  Completely sealed.

b)                  Maintenance free.

c)                  60% more capacity in accumulator.

d)                  Under test conditions battery case offered nine times more resistance to abrasion and impact than the old unit.

e)                  Fits all existing charging units but for complete technical compatibility the new charger and frame are recommended.

f)                    Extra burning time and even illumination.

g)                  Leak proof even if container is damaged.

h)                  Re-sealable safety - the inner seal allows gas to be released if battery is seriously over charged.

i)                    New cable lock which prevents cable from being pulled out of lamp or battery unless force exceeds 670N at the headpiece.

j)                    Flame resistant container for underground application.

k)                  Tamper proof - special tool needed to take off lid.

l)                    Stainless steel shoe available for hard-rock mines.

m)                New lamp fits onto any standard helmet.

n)                  Six times greater lamp output.

o)                  Charging rack designed to take 10 lamps or multiples thereof with features which make it easier to handle and offer longer life.

Colin Priddle’s note: "I’ve got two of them cost £16 each (R32) Charger (R30).  They are superb, Terrific beam, 16 hours light".