Development of long-life small-capacity VRLA battery without dry-out failure in telecommunication application under high temperature environment

We have developed long float service life small-capacity VRLA battery without dry-out failure in tele-communication application. We had reported the development of medium size (12 V 15 - 65 Ah at 20 hours rate), life expectancy of 13 years at 25 degree C, VRLA batteries in 1997. The batteries employed the newlead alloy grid and grid design which had improved corrosion resistance of positive grid, while at same time they could reduce their float current at high temperature by the effect of new additives into the negative active mass. We have developed the advanced technologies, especially in the point of the suppression of dry-out failure, and applied them to the small-capacity VRLA batteries, because the dry-out failure was the most prominent for these small-capacity VRLA batteries. We had already studied the inhibition of increase of internal resistance even if much water was lost, and reported that AGM separator easily shrunk and lost compression to the plates after some amount of water loss, which caused the premature capacity loss in 1995. We employed both the new AGM separator and the new manufacturing method reported in [2] not to lose the initial high compression during operation in the small-capacity VRLA batteries. Furthermore the prevention of water loss in itself could be achieved by employing a new container plastic material with a low moisture permeability ratio. We provided 12 V 7 Ah (at 20 hours rate), 10 years expected life at 25 degree C, VRLA battery with these newly developed technologies.