Free Battery C-Rate & Peukert Runtime Calculator

Q: What is the Peukert exponent for LiFePO4 batteries?

The Peukert exponent for lithium iron phosphate (LiFePO4) batteries is typically between 1.02 and 1.05, meaning capacity remains virtually flat regardless of whether you discharge at 0.1C or 1C.

Q: Why do lead-acid batteries die so fast under inverter loads?

When running a 1,000-Watt microwave off a 12V inverter, the battery draws approximately 85 to 95 Amps (a heavy ~1C rate on a 100Ah battery). Peukert effect causes the internal voltage to sag immediately below the inverter 10.5V cut-off threshold, triggering a premature low-voltage alarm.

Q: What is Depth of Discharge (DoD)?

Depth of Discharge is the percentage of battery capacity that has been discharged relative to overall capacity. Deep cycle AGM lead-acid batteries should not exceed 50% DoD to avoid rapid cycle degradation, whereas LiFePO4 safely handles 80% to 90% DoD for 3,000+ cycles.

Q: How do you convert discharge Watts to Amps?

Amps = Watts / Nominal Battery Voltage. For example, a 600W load on a 12V battery draws: 600W / 12V = 50 Amps.

Calculate real-world battery discharge runtime and effective capacity under heavy C-rates using Peukert’s equation for LiFePO4 and Lead-Acid.

⚡ Battery Chemistry & Load

Battery Chemistry & Peukert Exponent (k)

Rated Capacity (Ah) e.g. 100Ah 12V battery

Hour Rating Basis (hr) Standard: C20 (20 hrs)

Nominal Voltage (V) 12V, 24V, 48V

Discharge Load Input

Continuous Load (Amps) 320 Watts equivalent

📊 Real-World Discharge Output

Estimated Runtime 0h 0m 0.00 hours exact

Discharge C-Rate 0.00C 0.0 A continuous

Effective Usable Capacity 0.0 Ah 0 Wh energy

Peukert Capacity Loss 0.0% Safe DoD: 90%

Peukert Equation: t = H × (C / (I × H))^k

Total Stored Nameplate Energy: 1,280 Wh

Chemistry Thermal Stress: Low Thermal Stress (<0.5C)

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Frequently Asked Questions

What is the Peukert exponent for LiFePO4 batteries?

The Peukert exponent for lithium iron phosphate (LiFePO4) batteries is typically between 1.02 and 1.05, meaning capacity remains virtually flat regardless of whether you discharge at 0.1C or 1C.

Why do lead-acid batteries die so fast under inverter loads?

When running a 1,000-Watt microwave off a 12V inverter, the battery draws approximately 85 to 95 Amps (a heavy ~1C rate on a 100Ah battery). Peukert effect causes the internal voltage to sag immediately below the inverter 10.5V cut-off threshold, triggering a premature low-voltage alarm.

What is Depth of Discharge (DoD)?

Depth of Discharge is the percentage of battery capacity that has been discharged relative to overall capacity. Deep cycle AGM lead-acid batteries should not exceed 50% DoD to avoid rapid cycle degradation, whereas LiFePO4 safely handles 80% to 90% DoD for 3,000+ cycles.

How do you convert discharge Watts to Amps?

Amps = Watts / Nominal Battery Voltage. For example, a 600W load on a 12V battery draws: 600W / 12V = 50 Amps.