[Al Skierkiewicz]

Mike,
The manufacturer's spec is based on constant voltage dumb charging, so 5.4 amps is something they are comfortable with. Since the KOP charger is a smart device it uses typical lead acid techniques like delta V or some other profile. This where the charger is pumping current periodically and then testing the the battery without charge current. It compares the level of the battery now compared to previous samples and adjust the current (voltage) accordingly. The only improvement on this method would be to monitor internal temperature as part of the charge cycle. As the battery nears and reaches full charge the delta V levels off and actually starts to descend at full charge. At this point most chargers will stop charging or move into a maintenance charge cycle that is similar to trickle charging.
Something to keep in mind is that dumb chargers are usually unfiltered, rectified line voltage so the current meter is actually only reading average current but the peaks are much higher. Although the manufacturer that I spoke with a few years back was reluctant to agree, it is my thought that excessive charging currents (which require higher voltage to produce) may actually cause arcing between the closely spaced plates in AGM cells. If this is actually occurring, then the damaged plates can have reduced area and therefore reduced capacity or in rare cases, the plates may short internally. We know that some teams have experienced shorted cells, but in many cases that I have examined, the case showed signs of rough handling. In some cases there was no external damage visible so I have to conclude either a defect in manufacture or an arc internal to the cell. In a few of these cases, a charger defect was discovered. As you investigate charging circuits you will discover that all of them have some power device that feeds the charge current to the battery. Often these are similar devices to the MOSFETs you would find in a Victor or Jaguar. If that device should short on failure, you would deliver full power supply voltage to the battery under charge. I can't tell you that this was the case in the battery failures that have been reported simply because there are so few failures.
As to gas generation, high charge currents produce heat in the electrolyte in the glass mat. If this temperature is high enough, the electrolyte will start to boil. Also due to the electrical action some of the water will actually disassemble into separate hydrogen and oxygen atoms. Combine high temps, boiling electrolyte and hydrogen formation and the internal pressure of the battery will cause some venting through the vent plugs in each cell. In our batteries this is nothing to worry about as the gas production is relatively small and confined to the battery in most cases. As charging tapers off, the gases recombine and are reabsorbed by the glass mat.