HALF CENTURY OF THE VRLA BATTERY
While the history of its invention and its revolutionary chemistry is one fascinating story, the route to commercial success for the VRLA battery is equally as complex and intriguing. Some of this prefigured the arrival of Batteries International, but the story continues to this day.
From conception to mass production … to start-stop
The first company to seriously look at developing the VRLA battery further was Gates Rubber Corporation, which also registered the first patent for this in 1972 — for in-depth story go to page 110.
The Gates Corporation was one of the largest privately held companies in the US with its operations mainly focused on the automotive sector, industrial rubber products and petroleum property development. Gates Rubber Company, the largest of its subsidiaries, generated about 75% of the company’s total revenues and is considered the world’s largest non-tire rubber company.
The company moved into battery making in the 1960s and developed the original VRLA battery – as outlined in the previous article. But its eventual commercialization came about as the result of an unlikely encounter and eventual technical collaboration with Chloride in the 1970s.
Gates had been advised by the Arthur D Little Organisation that small sealed rechargeable batteries, suitable for use in cordless tools, would be a good product to sell in forecourts alongside their other automobile equipment. The company employed a group of researchers and scientists, mostly experienced in small alkaline cells such as nickel-cadmium, popular at that time but expensive.
In the 1950s scientists at AFA in Germany developed and produced small nickel-cadmium cells that worked on the basis that oxygen evolved during recharge recombined at the cadmium negative electrode, producing water. They required no maintenance, could be sealed and were popular in portable tools, equipment and alarms.
The Gates team included John Devitt and the late Don McLelland, co-inventors of their 1972 patent. Their work, starting in 1965, concentrated mostly on lower cost batteries such as nickel zinc and lead acid.
Other than this programme, the company had little background or experience of main-stream battery manufacture and production.
Separately, Chloride had been working on a similar concept for some time. The catalyst for the work had been the success of the nickel cadmium cells now being used increasingly in portable tools and equipment. As well as being sealed units, maintenance free and with the ability to convert oxygen to water during recharge at the cadmium electrode, they were also spill proof with no noxious and dangerous gases emissions.
The Chloride work explored whether similar designs and mechanisms would function in lead acid cells. At the time, gel batteries with immobilized electrolyte were used for this market, the principal manufacturer being Accumalatoren Sonnenschein. They were unspillable but the gels were subject to drying out and cracking with rapid loss of performance.
Ken Peters was to be instrumental in the commercial development of the VRLA battery. He joined The Chloride Electrical Storage Company at its new R&D facility under the direction of Montefiore Barak — a charismatic New Zealander who was one of the outstanding research leaders of his generation.
His early assignments included the development of a plating process for torpedo batteries for the UK Admiralty, the development of impregnated cellulose separators for SLI batteries, .subsequently manufactured at Chloride plants, and the assessment and qualification of leady oxides made in a new design of oxide mill.
He was made manager of the lead acid development group in 1957 with a staff of graduate chemists, engineers and technicians engaged in process and product development, including the study of oxides, additives/expanders, alloys, grid, plate and cell designs.
High antimonial alloys were standard in the industry and with the use of grain, refining additives to improve casting and ductility, the antimony content was progressively reduced, giving corrosion resistant grids and reduced water loss in service.
An extensive range of expanders were studied to optimize the performance and improve the stability of negative plates. Several patents were filed and in some instances the work was published externally. A report on negative plates was produced for the Advanced Lead Acid Battery Consortium (ALABC) in 1997.
In 1958, Chloride Group, The Electric Storage Battery Co in the USA and Accumulatoren Fabriken Aktiengesellschaft (AFA, later Varta) in Germany, the three dominant battery makers at that time, signed a technical exchange agreement.
Executives from the two companies had regular meetings in the US, Germany or the UK to discuss and exchange technology with eminent electrochemists. This arrangement was subsequently ruled illegal and was cancelled after a few years.
Among the research topics in the early years were studies on the charge acceptance and charging efficiency of positive and negative plates by measuring the rates of cathodic hydrogen and anodic oxygen evolution at different charge rates and temperatures.
It demonstrated the high charge efficiency of the negative plate, remaining at 100% for a time dependent on rate and temperature.
The study was presented at the International Power Sources Symposium (IPSS) in 1970. Alongside this work, Peters studied the oxidation of negative plates, primarily to assess the feasibility of an oxygen recombination cycle similar to that in sealed Ni/Cd cells… finding good recombination efficiencies at high charging rates was feasible with saturation being the main controlling parameter.
Subsequently, several hundred D cells were made with wound electrodes but the performance was relatively poor and since Chloride had little presence in the small consumer battery market the development was shelved. Its work was presented and compared with the performance of similar size Ni-Cd and Leclanche cells at the 1972 IPSS meeting.
A chance encounter
It was a chance meeting at the 1972 conference that brought the two companies together.
At that meeting, Don McClelland of Gates Rubber Company approached Peters to discuss the concept. With his co-inventor John Devitt, McClelland had been working along similar lines and subsequently sent Peters some 50 D size sealed lead cells for testing.
They used highly porous and compressible glass filter paper as separator (the main inventive claim of US patent 3862861, published in 1975) and the cells had high power capability, cycled well and could be charged extensively without water loss.
After testing, Peters suggested to his management that a similar approach but with prismatic designs rather than wound cylindrical shape could be used in Chloride’s main industrial and automotive business to substantial benefit and early in 1973 he was invited to Denver, Colorado, to attend a meeting of the Gates Board of Management. They had little experience or background of the battery industry and a detailed explanation of the technology and the potential market was presented.
A joint working group with Gates was set up to consider the way forward. Gates was keen to keep the wound cell design but its manufacturing process was slow, expensive with high scrap levels and it was difficult to see how this approach could be used to manufacture the larger batteries needed for industrial and automotive applications in the numbers required and at acceptable cost.
Different approaches were agreed. Gates would continue to develop 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 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 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
grounds it had prior art of the use of glass microfiber separators, a primary claim in the Gates patents. It succeeded in its court case against Gates.
The patent side of this was interesting. Gates’ original patent officially ran out in 1992, but extensions were possible of commercial introduction was delayed. Because of their agreement, Chloride never paid Gates royalties. Other companies including Tungstone did, while Yuasa won a patent case against Gates claiming knowledge of some prior art.
Geoffrey May, now a consultant but formerly an executive at both Chloride and Tungstone, says that the telecoms industry was the first to truly understand the potential of the technology and embrace it. “They developed a six volt battery and that was very successful. BT rolled it out on a big scale and other telecoms companies followed,” May says.
All this relates to the AGM form of the battery. The development of the gel version was taken up by German company Accumulatorenfabrik Sonnenschein.
With gel electrolyte the separator was no longer such a critical, hard-to-make component, and cycle life was increased, in some cases dramatically.
The move into automotive
At the same time as the standby battery work, in the mid-to-late 1980s chloride started work on a design suitable for use in automotives. For the same reason the technology had been successful in telecoms it was believed it could also revolutionize the batteries being used in cars.
The company started developing valve regulated car batteries with similar beneficial features ie leak and spill proof, zero maintenance, improved cycling and with a much improved cranking performance plus dual terminals (top and side), multiple hold-downs, a carrying handle and stackable features, all novel at the time.
The first market where this was really tested was in Australia, mainly because of concern that Pacific Dunlop, its main competitor, would launch its newly developed Pulsar battery and threaten its business.
Production of this battery (TorqueStarter) started in Brisbane, Australia, in 1984. The battery was a success – not in the original equipment market but instead by being marketed as a better option in the replacement market.
Backed by a strong marketing operation, the battery flourished for a few years before Pacific Dunlop acquired Chloride in Australia and phased the battery out in favour of its own technology, which included Pulsar.
Chloride then looked to roll the design at its other plants including the Dagenham factory in the UK, Benoni in South Africa and Tampa, Florida in the US. Successful manufacture required tighter component tolerance and higher purity levels, all at a higher cost, estimated at ~10%.
Several attempts were made, particularly in the USA, to persuade vehicle manufacturers to accept the TorqueStarter design as original equipment but existing batteries were adequate and the higher cost was not acceptable.
The batteries made in Tampa and Benoni had quality problems with early failures and production ceased a year later.
In Australia and the UK, after good early sales, demand decreased due to the price, and production stopped three years later.
“Torquestarter was a good battery with distinctly beneficial features but the higher cost of purchase was difficult to justify,” says Peters.
“Some 20 years later with demands for improved fuel economy and low emissions, car manufacturers are now prepared to modify the car’s electrical system and the improved features of VRLA designs can be very advantageous.
“Since these batteries are truly maintenance free and unspillable, designers are amenable to locating the battery away from the engine compartment and in positions where easy access is not essential.
“The support provided by the compressed glass separator results in a more durable battery with service life much improved on cycling and on difficult terrain. They are lighter than flooded designs and with the low internal resistance, starting power is much superior. As a consequence they are usually preferred in the cleaner stop-start mini-hybrid vehicles.”
More recently, similar valve regulated designs have been used in advanced designs of cars, providing freedom for location and improved cycling performance, and supporting changes aim to improve fuel economy and reduce emissions.
Peters says: “You have to remember that in the 1980s and 1990s there was no real benefit to using valve regulated batteries as such because people were simply not sensitive to their benefits. Manufacturers and customers simply bought based on price and little else. They just wanted any battery to do the job.”
Peters says that when manufactured correctly, it was a very good product. “It was an excellent design. The batteries were stackable, easy to handle, they had multiple terminals. We also developed very high quality manufacturing out there but that wasn’t always easy in other parts of the world.”
The 10% to 20% extra cost was seen as prohibitive despite the benefits. “The market was all based on price, there was no benefit to the car maker and people saw existing batteries as adequate. It was very difficult to gain traction,” Peters says.
It has only been in the past decade that the VRLA battery has enjoyed breakthroughs in the automotive market and these have been driven by pressure on manufacturers to lower emissions and reduce the carbon footprint of vehicles.
May agrees that there was a fundamental reluctance in the automotive market to buy a more expensive product despite its proved better performance. “That market is so price sensitive, it could never have been commercially successful at that time irrespective of whether they had better technology specifications,” he says.
“It was in stark contrast to the standby power business where there was a tolerance for life and performance advantages. The automotive industry took some years before industry got its head around the technical solutions this could offer. Also, the development and take-up of start-stop technology has been particularly important to the development of VRLA batteries in this field.”
Peters says that while different car makers have different views on which battery they prefer, he believes the VRLA battery still has a strong future in the automotive market.
“The concept still holds tremendous potential with the designs now allowing for huge power density. I think this will be the future for lead acid batteries,” he says.
Gates later sold its UK business to Hawker Batteries, then part of BTR/ Invensys, when it became Hawker Energy Products. It extended the range of prismatic batteries from the aircraft battery range to standby power, which became the backbone of the business.
Gates had by then moved its US battery manufacturing from Denver to Warrensburg in Missouri and when the original Gates patent on VRLA batteries expired, the revenue stream that it had enjoyed dried up and it also sold this business to Hawker.
Both of these companies have expanded over the years and are now part of EnerSys which acquired them from Invensys.
The thin-plate pure lead product it supplies is only made by a limited number of companies and is a premium product compared to other types of VRLA battery.
In the last 15 or more years, VRLA AGM batteries have become the principal product offer for standby batteries, are important for micro-hybrid/ start-stop applications for automotive and are used in a wide range of batteries for cyclic service.
China dominates as the leading supplier for small and larger standby batteries and all major battery manufacturers have full ranges in their product portfolio.
Peters retired from Chloride in 1991 and has since advised battery companies and suppliers in the USA and Europe. He was a member of the editorial board of the Journal of Power Sources for 20 years and has served on the Technical Advisory Committee of European Lead Acid Battery Conference for 25 years.
May continues to work as a consultant in many aspects of the industry.