HALF CENTURY OF THE VRLA BATTERY and produce small wound consumer batteries as it originally targeted and Chloride, in exchange for advice on improving Gates manufacturing operations, would develop and manufacture larger prismatic designs for the automotive and industrial markets free of patent constraints and royalties. The year was 1974 and by this point Chloride had the green light to start developing industrial scale prototypes. Over the next few months, the original technology was refined in several ways. A key breakthrough was enhancing the separator technology. This was a key component of the design and the patent claims. Purity, stability in the corrosive environment and a highly porous microcapillary structure to hold the necessary amounts of electrolyte and allow sufficient gas transport were essential. Gates had used custom-made and expensive microfine glass filter paper. Chloride refined what was needed and found a suitable supplier in the UK to manufacture at an acceptable cost. Extensive trials were carried out to define design parameters. Methods of acid filling, formation schedules and assembly procedures were developed and low pressure one-way valves designed together with structural improvements to the container.
“The automotive market is so price sensitive, it could never have been commercially successful at that time irrespective of whether they had better technology...
First usage
The rapidly growing Telecom and UPS market was considered initially and British Telecom, a major customer, were approached. The conventional back-up power supply at that time was large Plante cells located in central stations usually in the basement of buildings in large conurbations, often with open top units which required frequent maintenance and resulted in a noxious and hazardous working atmosphere. BT was concerned about this arrangement and wanted to move to distributed and localised power supplies, seriously considering the use of the more expensive Ni-Cd cells in place of lead acid. The newly designed valve regulated lead acid cells were smaller with much higher power ratings than existing batteries and with no water losses or gases evolved. They could be located on power racks or cupboards in offices or where most convenient to the end user. Chloride started to develop designs in plastic containers specifically for the telecoms sector. Cells were supplied to British
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“…. it was in stark contrast to the standby power business, where there was a tolerance for life and performance advantages.” Telecom for trials in 1978/9 and produc.”tion commenced in 1983. By 1989 BT had installed 500,000 2V/100Ah valve regulated cells in power racks in their System X digital telephone exchanges and were installing them at a rate of 120,000 per year. In 1990 they reported reliability, based on mean time between failure exceeded their target. Within a few years distributed power supplies with similar valve regulated cells were adopted worldwide. Fitted in racks and cupboards where required, with zero maintenance and no noxious fumes, they were space saving and more reliable. Chloride was by far the biggest supplier to this sector in the 1980s and 90s.
Tungstone, which was to become part of the Hawker Siddeley Group, was also targeting the telecoms sector, offering a very similar product and competing directly with Chloride. It worked extensively with BT and had a good share of the business. Subsequently similar VRLA designs were adopted worldwide for Telecom systems and also for use in Emergency Power (UPS) where the low internal resistance and high power performance was a major benefit. Other manufacturers, with the exception of the Yuasa Battery Corporation of Japan, paid royalties to the Gates Corporation for the 20-year duration of its patents. Yuasa appealed against the Gates patent on the
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