My Xantrex TC20+ was new (when I installed it) in 2005.
Never-the-less, it has three separate outputs for three separate batteries (or banks). Yes it does detect the state of charge of each individually and can provide different output charging currents to each. The thing to remember however is the total of the three will always be 20 amps. So as one battery fills up the others will split the now available capacity. But as many have done, its okay to gang all three outputs together and charge a single battery or single bank then use a battery combiner to switch to a second bank when the first one is charged. This automatically splits the load on the three outputs so any one is not stressed to its maximum output.
Since my boat is mostly at the dock, 20 amps has seemed to be fine even with 4 6 Volt batteries (400 + amp hour capacity). Even at 50% discharge when I get home it only takes 10 hours or so to charge up again. I usually don't discharge that much after a long trip and I don't get back to the boat for a week or more anyway. Some have also said that the lower rate of charging on the batteries can result in a better charge when taken to completion.
