Here is a description for maintaining Ionic lithium batteries from Ionic Batteries.

For the IONICs, and im only speaking for IONICs, the engineers charging specs differ just a little from what others may say, but for the most part they are very flexible, during fishing season if you choose to plug in every time and they are at 80% do it, you will not shorten the life of this battery and if you are running 50ah I highly recommend charging every time unless you know you are only fishing short days, its ok to drain the battery dead every now and then but for the best battery life you want to keep them above 20% and its easier to do that if you start out at 100%, The IONIC will use partial cycles so you can charge 5 times from 80% and only use one cycle, but if you use down to 40% they will equal a cycle, with the 100ah you can go 2 or 3 trips if you like but dont not leave them sitting for a long time below 50%,
when you do charge you can plug in and leave it with the proper charger or charge and unplug it really wont matter because the charger will never come back on any way for months unless the power goes off and comes back on and restarts the charging cycle , there is no maintenance mode on lithium, they charge then the float., Find a routine that works best for you and use the app, when it comes to lithium's dont every rely on the lights on the charger no mater what charger you have. I usually charge a day or 2 after fishing and unplug, if its been a coupe weeks I may plug in the charger the day before to top off.