Power Station Battery Storage Voltage: Optimal SOC for Long-Term Storage

Volume I  ·  May 2026  ·  207 words

LiFePO4 batteries degrade slowest when stored at 50-60% state of charge and at temperatures below 25C. Storing at 100% SOC accelerates calendar aging — the cells spend more time at high voltage, which promotes electrolyte decomposition and increases internal resistance. The EcoFlow Delta 2 and most manufacturers recommend storing at 50-80% SOC and recharging to this level every 3-6 months to compensate for self-discharge. For a power station kept in emergency readiness, the trade-off is between battery longevity and available capacity when an outage occurs. The compromise: store at 80% SOC — enough for most outage scenarios — and cycle the battery (discharge to 40%, recharge to 80%) every 3 months. This maintains approximately 90-95% of the capacity available for emergencies while reducing calendar aging compared to 100% storage. A unit stored at 100% SOC in a hot garage (30-35C) may lose 10-15% capacity in 2 years from calendar aging alone, versus 3-5% loss for 50% SOC storage at 20C.