Hey Darin, I saw you mention a desulfator earlier in this thread. Did you ever try anything like that for your batteries?
I found a homebrew circuit for a desulfator a while back. Here is a site that shows some details
http://www.alton-moore.net/graphics/desulfator.pdf
and here
http://www.dallas.net/~jvpoll/Batter...n_Units23.html
I've built 3 so far (2 for at home and 1 for at work) with good success. We use lots of lead acid batteries at work so we use a store bought desulfator to maintain them sometimes. We wanted more but without the $50 price tag. That's one reason I looked into DIY versions.
I recently brought a 2.7ah 12v SLA back from the dead with the homebrewed circuit in just over a week. The store bought one we use did the same thing with one a month earlier, but took a little longer.
I modified the circuit so I can use a wallwort as a trickle charger if needed. I believe the 12v circuit can do 6v batteries since the timer IC needs only 5v to run. There is a 24 volt version too. There are also ways to make them higher power for really large batteries.
Heres a good forum about them too.
http://leadacidbatterydesulfation.yuku.com/