Seems clear to me that "cycle service" means running them down some and then recharging again as their normal existence. Float service would be like a stand-by power supply or UPS set-up.
Phil has a good reason not to follow the specs exactly ( equipment) and is getting away with it. I think Phil must be right that the occasional alternator charging at 14.x must be what is saving him.
So his example is not any proof that you could do "cycle service" with his batteries using only 13.8v. That is an unknown, unless Mex knows.
