Answer: The best 3.2V LiFePO4 batteries for DIY solar systems are Grade A cells with 310–320Ah capacity, designed for longevity (2,000–5,000 cycles), safety (thermal stability), and scalability. They enable custom 12V/24V configurations for RVs, boats,… What Are the Best 3.2V LiFePO4 Batteries for DIY 12V/24V Solar Systems?