How do I calculate battery backup runtime?

Runtime (hours) = Battery capacity (kWh) × DoD × inverter efficiency / Load (kW). A 10 kWh battery at 90% DoD with 95% inverter powering 2 kW load: 10 × 0.9 × 0.95 / 2 = 4.28 hours.

What DoD limit maximizes battery life?

LFP batteries: 80-90% DoD is standard for daily cycling. NMC: 70-80% for longevity. Never fully discharge any lithium battery (leaves cells at low voltage state that causes permanent capacity loss).

How does temperature affect battery runtime?

Cold temperatures reduce Li-ion usable capacity: at 32°F, expect 80-85% of rated capacity. At 14°F, only 60-70%. Conversely, high temperatures (>95°F) don't affect immediate capacity but accelerate long-term degradation.

Battery Backup Runtime at Load Calculator

Calculate how long a battery bank (kWh capacity) will power a given load (W or kW) accounting for depth of discharge limits and inverter efficiency.

2D stress state at a point. All stresses in MPa.

σx — Normal Stress X (MPa)

σy — Normal Stress Y (MPa)

τxy — Shear Stress (MPa)

⚙ Mechanical Note: Results are based on standard textbook formulas and ISO/AASHTO references. Always verify critical designs with applicable codes (ISO 898, AASHTO 1993, AISC, Eurocode 3) and a qualified engineer.

How to Use

Enter the values for the patient or scenario you are assessing. Calculate how long a battery bank (kWh capacity) will power a given load (W or kW) accounting for depth of discharge limits and inverter efficiency. Use the battery runtime result to inform your clinical assessment.

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Battery Backup Runtime at Load Calculator

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Frequently Asked Questions

How do I calculate battery backup runtime?

What DoD limit maximizes battery life?

How does temperature affect battery runtime?