Mechanism Side reactions at anode surface consume Li+.
SEI growth consumes lithium irreversibly.
Electrolyte decomposition (slow, temp-driven).
Rate: ~1–3% SOC/month at room temp.

Temperature effect Doubles ~every 10°C (Arrhenius).
At 45°C: 4–8% loss per month.
At 0°C: <0.5% per month.
Cold storage = much less calendar aging.

Best storage practice Optimal storage SOC: 40–60% (reduces stress).
Optimal temperature: 10–15°C (cool, not freezing).
Tesla recommends 50% if parked >1 week.
Never store at 100% — accelerates SEI growth.

BMS role Wakes periodically to check cell voltage.
If V_cell drops below UV warning threshold,
sends CAN alert or SMS via telematics.
Parasitic drain from BMS itself: 1–5 mA.