In response to market demands, Chloride Automotive Batteries Limited have produced a sealed battery which has long shelf life, will not spill acid if upset, needs no maintenance or topping up and is covered by a two tier guarantee for four years — free replacement if the batters’ fails in the first two years of service and the opportunity to buy a replacement at half price if failure takes place in the second two years. Available from October 1st under both the Exide and Dagenite brand names, the range of ten batteries with “Sealed for Life” cells will suit the majority of cars and light commercial vehicles fitted with alternators and the scope will be extended to cover virtually all such vehicles. “Sealed for Life” cells have been made possible by significant advances in two aspects of battery design — first, in the alloy used for the electrodes and second, in the construction of the cell vents. Lead of itself is not strong enough in batters plates as it is soft and tends to warp. Most manufacturers employ a lead antimony alloy, but the presence of antimony tends to cause gassing with a consequent loss of electrolyte and performance. The “Low Maintenance” range of batteries produced by Chloride last year were the first to employ plates with a significantly reduced antimony content and the new range has gone one step further in doing away with antimony altogether. The alloy now used is made from lead with calcium to provide rigidity and tin to provide resistance to damage due to overcharging. Used with a properly regulated alternator charging system, gassing has been virtually eliminated and shelf storage life considerably increased. (These batteries are not compatible with dynamo systems because the rather higher voltages experienced from this form of charging system tend to cause gassing, even with the new alloy.)
The other step forward is in the design of the cell vents. It is essential to have some form of ventilation to enable any small amount of gas which may be produced to escape. The problem in the past has been that the electrolyte has been able to evaporate and the water vapour to escape through the vents, thus making relatively frequent topping up necessary. Chloride’s new design employs “Vyonguard Vents” which have spray arresters to condense most of the water vapour, returning it to the electrolyte. and a special microporous disc, made of “Vyon” (sintered polypropylene), which acts as a filter preventing any remaining moisture from leaving the cell while allowing any gases given off during charging to escape. “Vyonguard Vents” are able to cope with any temperatures likely to be experienced in Europe and other temperate areas, but are not recommended for service in very hot conditions. — PHJW.