I have been going back and forth with Magnum and Lifeline, trying to make sense and integrate their recommendations for charging our new AGM battery bank, but that is another story.
In the conversations, and my pouring over the 139 pages of Magnum programming instructions and Lifeline technical manual, one of the charging profiles was called "constant current/constant voltage". It appeared to be a two stage charge profile with shutoff and rebulk. It passed my mind that it might be good for lithium, but I don't know that much about lithium, and am maxed out on battery research with what we have.
What did happen, however, was that the Magnum tech I have been communicating with (great folks to deal with) mentioned for me to look at that profile for our use (which it is not good for) even though they "designed it for lithium" in his words. That kind of confirmed what I had suspected about using it for lithium, and it does appear that it would be just what many experts want.
It does constant current Bulk charge, constant current Absorption charge, transitions out of absorption on return amps, shuts off charging, monitors the battery voltage, starts the charge process over when it hits a programmed battery voltage. Since the return amps and rebulk voltage are easily changed, it would be easy to quickly change it to a 50% SOC for long term storage. Looks good at first analysis. It is available on all the Magnum inverter/chargers as long as you get a remote and battery monitor kit. That includes the new smaller units that are much more competitively priced.
Here is what the charge profile looks like.