On Fri, Apr 29, 2011 at 12:22 PM, Dwayne Reid wrot= e: > My preferred battery technology is still Lead-Acid. =A0I use gell-cells > (AGM) for small projects and flooded batteries for larger installations. Just one point - AGM and gel are not the same thing, both in construction and behavior. The DO both fall into the category of Valve-Regulated Lead Acid (VRLA) batteries, where Hydrogen production during charge is reduced and Oxygen which is produced can re-combine with H+ ions to form water again - thereby eliminating the need to add water and allowing the battery to be sealed except for one-way valve vents to allow occasional escape of gas during over-charge. AGM stands for Absorptive (or Absorbative) Glass Mat. The electrolyte is truly a liquid in AGM cells, but it is retained within the separator material which is a like a thin "rat's nest" of glass fibers of varying length and diameter. The adhesion of the electrolyte to the glass keeps the electrolyte from leaking out as long as the height of the cell is limited. Gel cells actually use a gelled electrolyte, made from sulfuric acid and usually fumed silica. The separator material is usually much thinner and similar to that used in flooded lead-acid batteries (a porous plastic sheet). Gel cells usually cannot handle very high charge and discharge rates as well as AGM can. Gel cells are also more subject to failure from punctured separators since the separator is thinner than in AGM. However, depending on the battery design, Gel type batteries often have a longer deep cycle life and sometimes a longer float life, too. The failure modes are different since the gel can become detached from the plates whereas for AGM, the liquid electrolyte will generally maintain contact with the plates even after dimensional changes. AGM cells also can have a high clamping force to hold the plate stack together which tends to reduce active material shedding. Just reading up on this lately and couldn't let the point of AGM vs Gel difference go :) Sean --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .