I'd contact them, or go to their site to get the recommended procedure if you are a prospective purchaser, or original-owner. This is especially important to demonstrate a warranty.
Generally speaking, there is no need, nor is it actually desirable to HOLD lithium batteries (lfp or non-lfp) at full charge.
HOWEVER, to make sure that the battery of cells is balanced by the internal bms in most pre-built battery banks, then an initial charge to 100% is advised to balance out any small variations of cell capacity or soc when initially received.
Afterwards, you are under no obligation to charge back to 100% as long as your charge meets your capacity needs. But, due to natural aging that happens with all chemicals, I'd return to 100% once in awhile to help maintain a proper balance. With a BB, this shouldn't be a problem. With cheap junk, yeah, you might have to do this more often to nurse trash cells.
80-30% is a fine way to go. Just know that striving to achieve this perfectly may be more effort than it is worth, when you factor in cell aging. Simply buy a little bit more capacity than you need, rather than try and crystal-ball the magic SOC numbers - which can be less than meaningful if chemical aging is not taken into account as the years pass.
It's a long way of saying that you can "outlive" the cycles available to you, when chemical aging starts to take more control (internal resistance) than mere SOC values. Just buy a little more capacity than you need so you don't have to worry so much and use it.
