3.43v cell voltage for LFP is the magic voltage. Any float voltage below this will have zero cell current (well maybe very small cell leakage current).
It takes 10-30 mV above or below 3.43v before any (mA's) of current starts to flows through cell. This is over-potential voltage required to push lithium ions to move through cell required for current to flow. So fully charged is really about 3.45v of no-load rested voltage.
You do not want continuous charge current to be imposed on a LFP cell. This will happen if cell if floated at greater than 3.45v. When you have continuous charge current, even a little, the SEI protective layer will continue to grow. This is a slow process, but it consumes some available lithium that will no longer contribute to cell capacity. It also increases cell impedance over time as the SEI layer gets thicker. Both these accelerate aging of cell.
When you put multiple cells in series, there will always be some variations between cells so 16x 3.45v = 55.2v overall charger float will have some cells above 3.45v. To provide some tolerance margin you should not continuously float above 16x 3.40v = 54.4 vdc. 53.8-54.0v is even better, giving more margin for cell matching variance.
A different problem that needs to be addressed is BMS balancing. If you continuously float at 3.40v per cell or below (54.0v) you will have very little balancing by BMS since most BMS's do not balance until a cell gets above 3.4v. So periodically you need to charge battery up to about 3.50-3.55v per cell (56.0v to 56.8v) for a few hours to give a chance for BMS balancer to operate. It should be done at least every month or two and soaked at 16x 3.5v = 56.0v for a few hours. You need to keep up with proper balancing or you will pay the price later when BMS keeps shutting down for over or under cell voltage with a lot of effort required to fix the large cell imbalance that grew over time.