Abstract: Filling a mat-immobilized-electrolyte battery with electrolyte. The battery's container includes a cover having two openings therein. The battery is laid on its side and electrolyte introduced thereinto through the lowermost opening. The electrolyte enters the battery at substantially the wicking rate of the electrolyte into the mat and displaces gases therefrom through the upper opening. Preferably, the battery will lay on its side in a tank of electrolyte whose level is just below the upper openings.

Abstract: An electrolyte-immobilizing mat for a mat-immobilized-electrolyte battery comprising a plurality of randomly oriented resilient fibers resistant to and wettable by sulfuric acid electrolyte, wherein the mat is held in a stressed, precompressed state by a resin which is substantially insoluble in sulfuric acid but is sufficiently degradable therein under battery formation conditions to free the mat from its stressed state during formation and allow it to swell within battery cell element. Thermosetting resins and particularly melamine-formaldehyde are preferred. The invention is particularly useful with mats made from glass fibers.

Abstract: An electrolyte-immobilizing mat for a mat-immobilized-electrolyte battery comprising a plurality of randomly oriented resilient fibers resistant to and wettable by sulfuric acid electrolyte, wherein the mat is held in a stressed, precompressed state by a resin which is substantially insoluble in sulfuric acid but is sufficiently degradable therein under battery formation conditions to free the mat from its stressed state during formation and allow it to swell within battery cell element. Thermosetting resins and particularly melamine-formaldehyde are preferred. The invention is particularly useful with mats made from glass fibers.