It is an AGM battery with certain recombinant abilities, and no listed upper limit on initial charging amps.
Whether the vent has opened and allowed some gas to release is an unknown. What I can say is the battery performs very well, and behaves much better after a high amp recharge from 50% to a 0.5% capacity amp tapering at absorption voltage. Behaves much better than a low and slow solar only return to full.
While I can notice it lost some of its violent engine cranking ability in its ~32 month lifespan and 350 deep cycles, based on voltage alone during discharge for the AH removed to the 50% range, I can detect no loss of total capacity. I am sure there is capacity loss, but in 100% to 50% depletion levels, I am not seeing any obvious signs of it, and am impressed with this battery, so much so that i no longer have a dedicated engine starting or house battery but use this one battery for both duties, and without fear.
All my available charging source's voltage, can now be precisely controlled, which was not the case when this battery was new and first started cycling. I was a the mercy of my vehicles voltage regulator, which was bat **** crazy, and a Schumacher sc2500a, which loved to go to 16+ volts at 25 amps and make any battery gurgle and gass.
MexWanderer set me up with an adjustable alternator voltage regulator, and turned me onto the adjustable voltage power supplies, and my solar controller is adjustable too, So I've got all bases covered, and a hard working hard cycling well performing high$$ AGM battery.
