RTFM

Just do like protec manual says.

NOTE: Brand new LiFePO4 batteries have been found to fail prematurely if they are deep discharged below 33% capacity too early. A break-in period of 20 cycles is currently recommended. While testing has shown that this battery can be charged at up to 3C rates, it recommended that this battery not be charged at rates higher than 1C to maximize the lifespan of the battery. Additionally, LiFe batteries should not be discharged below 2.5V per cell to avoid pre-mature failure and maximize battery life span.