LFP (LiFePO₄) Long-Term Storage

Target SOC: 50–60%.

• Safe range to store: 40–70%.
• Avoid 0% (risk BMS lockout) and 100% (faster calendar aging).

Temperature: Cool and dry.

• Ideal shelf: 10–20 °C (50–68 °F).
• OK band: -20 to 45 °C (-4 to 113 °F) for storage (not charging).
• Do not charge ≤ 0 °C. (Charge ≥ 5 °C to be conservative.)

Recheck cadence: Every 3–6 months.

• If SOC < ~35–40%, top back to ~55%.
• Packs with BMS/screens/trackers have parasitic draw—don’t abandon for a year.

Don’ts (LFP-specific):

• Don’t store full or empty.
• Don’t leave a charger “maintaining” 100%.
• Don’t let inverter/12 V loads trickle it down in storage. Physically isolate or open the breaker.

If you only have voltage (no SOC gauge)

Measure open-circuit after resting 1–2 h (no charge/load):

• Per cell (1S): ~3.27–3.30 V ≈ 50–60%
• 12 V class (4S / 12.8 V): 13.1–13.2 V
• 24 V class (8S / 25.6 V): 26.2–26.4 V
• 36 V class (12S / 38.4 V): 39.3–39.6 V
• 48 V class (16S / 51.2 V): 52.4–52.8 V

(LFP has a flat curve—small voltage shifts ≠ big SOC swings; treat these as targets, not absolutes.)

Quick checklist (use this and you’re done)

1. Charge/discharge to ~55% SOC (or voltages above).
2. Label pack with date + SOC.
3. Isolate from loads/chargers (breaker off or disconnect).
4. Store cool, dry, shaded.
5. Calendar ping every 3–6 months → if <40% → bump to ~55%.
6. For >12 months: do one balance-charge to ~95% then return to ~55% (keeps cells even; don’t leave full).

Parasitic draw reality

• Typical BMS quiescent: ~1–3 mA (varies).
• Rule of thumb loss: ~1–3%/month including BMS + self-discharge. Plan top-ups accordingly.

Before first use after storage

• Warm to >5–10 °C.
• Verify OCV ≈ targets above; if low, charge to 100% once to balance, then use.
• If BMS tripped on undervoltage, a wake-up/pre-charge may be needed before a normal charge.

Bottom line: For LFP, store ~50–60% SOC, cool, disconnected, and check quarterly. That’s how you minimize aging and avoid BMS brick.