Quote:
Originally Posted by Bob Denman
Thanks. I just got tripped up by the apparent lack of vents; so I figured that it would be safer to just ask.  |
AGM batteries are just a particular battery type of a category of batteries known as valve regulated lead acid batteries (VRLA).
A little deeper explanation - lead paste grid used in batteries is weak and would soon fall to the bottom of the batteries if it was not made of a alloy to make grids stronger. The common alloying metals are tin, calcium, antimony and selenium. Each alloying element does strength the lead grid, but also imparts some different characteristics to the batteries operation. When calcium is used to strengthen the grids the batteries out-gas little water when recharging. This means they can be sealed for normal operation. To prevent explosion when overcharged, overheated or when taken to high altitude there is a valve to regulate the battery's internal pressure. The batteries are commonly known as VRLA batteries. When the lead-calcium grids are are separated by glass mats filled with filled sulfuric acid they are known as AGM batteries but still are VRLA batteries.
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