How do you find the date code on a LiFePO4 battery? 

It depends on the age of the battery. For LiFePO4 batteries manufactured before 2024, it will be on a white sticker starting with the letters PS. For batteries 2024 and newer, it's inside the model number sticker.

Examples:

Old convention (prior to 2024):

PS20220929010458 =09/29/2022

Year - 2022

Month -09

Day -29

New convention (2024+):

PS12100BTG27D11001 = November 2023

A: Year, A for 2020, B for 2021, D for 2023

11: Month