lessons from a 13-year-old LiFePO4 bank

Takeaways from Rod’s Happy 13th Birthday to my LifePO4 battery bank thread.

Rod, posting as MaineSail, does rigorous testing and publishes the results on forums and his Marine HowTo website. This may be the best published real-world info on LFP to date.

his DIY 400Ah bank (Winston cells)

• 13 calendar years old, manufacturered in May 2009
• 2,300+ cycles to 80% Depth of Discharge
• charge to 13.8v at .4C (160A via marine externally-regulated alternator, supplemented by solar when the boat was docked)
• quasi-float at 13.4v
• BMS considered a safety net rather than active participant in charging/discharging
• most recent capacity test showed full 400Ah capacity

2,300 cycles over 13 years is a cycle every 2 days. People cycling daily to 80% DoD¹ might see these results after 6.5 years.

his general observations

• batteries largely unaffected by low discharge voltages ≥12v
• minimize Absorption duration to whatever is strictly necessary
• “cells did not need to charge to anywhere near 3.65V{pc, or 14.6v} to attain 100% state of charge

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1. and following his charging regime ↩