Different grades A+ or Automotive Grade or A- and B grade LFP cells?
A+ or Automotive Grade Cells (Revised October 2024)
Matched, Highest Quality Cells for Demanding Applications
Purpose: Designed for electric vehicles (EVs) and high-discharge applications, especially in high-voltage series packs where uniformity is critical.
Stress Tolerance: A+ Grade cells endure high charge/discharge rates, making them ideal for EV acceleration and regenerative braking.
Internal Resistance (IR): Consistently low IR simplifies balancing and enhances longevity.
Testing & Documentation: Manufacturers like EVE provide detailed reports, including IR, capacity, and voltage recovery over time.
Quality Assurance: Rigorously tested to meet strict performance standards.
Warranty: Backed by a 5-year Australian warranty.
Series Battery Considerations:
In a 16-cell 51.2V pack, if one cell has lower capacity (e.g., 200Ah vs. others at 300Ah), the pack’s usable capacity drops to the lowest cell’s level (200Ah), resulting in a 33% loss. This highlights the importance of uniform cell grading.
2024 Note: Improved manufacturing and reduced costs have made A+ Grade cells more affordable and viable for energy storage applications, especially for 16s 51.2V systems.
A or A- Grade Cells (Revised August 2024)
Often Rebranded B Grade Cells
Purpose: These are often B Grade cells modified (e.g., re-lasered QR codes) to appear as A+ Grade. Capacity and consistency are lower than true A+ Grade.
Cost: Rebranding typically adds $1–2 USD per cell, allowing them to be sold as A Grade.
Warning: Many A-Grade cells on the market are actually rebadged B Grade cells, making it difficult for consumers to discern true quality.
B Grade Cells
Cost-Effective, Less Demanding Applications
Purpose: Ideal for low-stress applications like lower discharge 12V batteries for RVs, caravans, or 4x4s.
Performance: Initially, B Grade cells may have similar capacity and IR to A+ Grade cells but degrade faster under heavy use.
Testing & Documentation: These cells lack official manufacturer reports but undergo third-party capacity testing.
Longevity: Suitable for low C-rate solar energy storage; they can last thousands of cycles if not stressed.
Market Reality: True B Grade cells are rarely sold openly and are often rebadged as A Grade. Reports suggest that 80–90% of large-format cells meet A Grade standards, but yield rates are inflated by manufacturers.
Cost & Warranty:
B Grade cells are 20–35% cheaper than A+ Grade cells. Reputable sellers may provide Australian-backed warranties, sometimes unknowingly for rebadged cells.
Summary
A+ Grade: Best for high-performance, 16s 51.2V systems and above; unmatched quality and longevity.
B Grade: Affordable option for low-demand applications but with lower reliability and lifespan.
