Not sure why you would want a 3 stage controller with AGM in a RE system.
I guess the "in a RE system" is the key here. Most of what I researched about deep-cycle and AGM batteries led me to folks on a wheelchair/mobility forum with some thorough discussions of the battery technology and proper maintenance. (can link if desired). In those uses/applications, the expert advice was 2-stage, or possibly 3-stage modern chargers. Also it seems that most
solar charge controllers provide 3-stage charging (some adding periodic equalization if applicable).
I suppose when you say RE system, that the implication is that the battery bank will always be brought up to good recharge level whenever the sunshine returns (unless the array is undersized), and in this application/system a float stage is unnecessary?
A dump controller IS a CC. A ghurd controller, in the standard format, is a PWM charge controller.
Thanks for clarifying that. Part of what got me thinking
adding the Ghurd device along with the CC, was Sparweb's post on your early development and beta devices -- he had a Morningstar Ts60 in the mix. His need and application was different than mine (he had solar + wind, and wanted to put the excess power to good use). But I latched onto the idea that the dump controller was an add-on.
I know a few options for the situation. The best by far is to get a better controller.
Ultimately I may have to cave and just go for a Morningstar or other 'popular' CC.
As for other options or solutions, I do want to see what else is doable and practical. Linear Technology has some ICs and modules gear to overvoltage protection. (LTC4365, Lt4363, etc) Other semiconductor co's as well. I just do not have the expertise to do it myself, and even if I found the right App-note, there are a number of things to get right in the execution -- and I probably wouldn't.
Thanks for your replies and help.