Turns out my charger was in trickle charge mode. 2a@12v. That charge, split between 4 batteries (with the powercheq mods) is not a lot of power to replenish the pack. That suggests the batteries may have simply been under charged on my second set of trips. So, i suspect I had the volts, but not the amps. However, waiting for a full charge has restored the pack.
The adventure into the 12v/powercheq way of charging is just a temporary measure. When my 48v side charger failed (from dropping one too many times) I thought about just getting another to replace it. The problem is, they are over $150! Instead, I'll be trying (4) Black-and-decker 12v-2a mini chargers. These don't charge up fast but four of these are less expensive than another 48v charger. They should also balance the pack when charging. Charging at 8AH, it would take 27.5hours to completely replenish the theoretical 220AH capacity of the pack. However, I don't anticipate drawing down the pack that far. If I drive moderately, I should be OK with overnight charging. Not that this will make a huge difference in my electric bill. The whole charging system will use in the neighborhood of 96W. So, I expect the charging cost on my utility bill would be approximately like leaving my porch light on all night.
The chargers could be mounted in the battery pan or on a shelf similar to the ones in this photo. Why use this particular Black and Decker kit? Each charger outputs 2A (versus normal 1A that most battery maintaners output). Plus, they come with all the cords shown which would save the trouble of putting on molex disconnects for future maintenance. These charger kits are available for $19.95 ea. (plus $4 shipping) from Tyler Tools.