Peukert’s Law Effective Battery Capacity & High-Current Discharge Runtime Calculator

Compute true battery runtime and derated capacity under high discharge currents via Peukert’s Law.

Peukert Actual Discharge Runtime
2.01 hours
Derated Effective Capacity (I × t) 70.45 Ah
Ideal Non-Peukert Runtime (C ÷ I) 2.86 hours
Capacity Lost to Peukert Effect 29.55 Ah
Inputs
⚡ Scenarios:
Ah
Nominal battery capacity C in Amp-hours (Ah).
hours H
Discharge hour rating H for nominal capacity (20-hr standard).
Amps
Actual continuous discharge current I in Amps.
k
Peukert exponent k (1.03 LiFePO₄, 1.15 AGM, 1.25 flooded lead-acid).
Results & Graph
Peukert Actual Discharge Runtime
2.01 hours
Derated Effective Capacity (I × t)
70.45 Ah
Ideal Non-Peukert Runtime (C ÷ I)
2.86 hours
Capacity Lost to Peukert Effect
29.55 Ah

Peukert Actual Discharge Runtime

Graph 1 • Peukert’s Law Battery Runtime • Domain Architecture & Live Telemetry Maps Rated Capacity Ah, Hour Rating Base H, Actual Load Current Amps through Peukert’s Law Battery Runtime Formula.
Peukert’s Law Battery Runtime • Generation → Conversion → Storage Bus 1. SOURCE / ARRAY 100 Ah Rated Capacity Ah 2. DELIVERED RATING 2.01 hours Peukert Actual Discharge 3. SECONDARY OUTPUT 70.45 Ah Derated Effective Capaci
Graph 2 • Peukert Actual Discharge Runtime Across Rated Capacity Ah Sweep (40% → 160%) Evaluates Runtime_hrs = H × [ C_rated / (I_load × H) ]^k; Effective_Ah = I_load across 7 operating points (current input highlighted).
0 hours 1.93 hours 3.85 hours 0.680 40Ah 1.10 60Ah 1.55 80Ah 2.01 100Ah 2.50 120Ah 2.99 140Ah 3.50 160Ah
Graph 3 • Joint Sensitivity: Rated Capacity Ah × Hour Rating Base H Compares Peukert Actual Discharge Runtime when Hour Rating Base H is shifted +25% (solid) vs. −25% (dashed).
0 hours 1.59 hours 3.18 hours --- Hour Rating Base H @ 75% 1.27 -30% 1.60 -15% 1.93 +0% 2.28 +15% 2.64 +30%
Summary: At a 35 A load (vs. 5 A nominal 20-hr rate) with Peukert exponent k=1.18, actual runtime is 2.01 hours (121 min) and effective capacity drops from 100 Ah to 70.5 Ah.
Summary: At a 35 A load (vs. 5 A nominal 20-hr rate) with Peukert exponent k=1.18, actual runtime is 2.01 hours (121 min) and effective capacity drops from 100 Ah to 70.5 Ah.
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Formula & Mathematical Methodology: Peukert’s Law Battery Runtime Formula

Runtimehrs = H × [ Crated / (Iload × H) ]k
EffectiveAh = Iload × Runtimehrs
Runtime_hrs = H × [ C_rated / (I_load × H) ]^k; Effective_Ah = I_load × Runtime_hrs
  • ratedCapacityAh: Rated Capacity Ah (Ah)
  • hourRatingBaseH: Hour Rating Base H (hours H)
  • actualLoadCurrentAmps: Actual Load Current Amps (Amps)
  • peukertExponentK: Peukert Exponent K (k)

Rounding: Engineering outputs round to 2–3 decimal places; discrete material bag/unit counts round up via ceiling.

Worked Example: Engineering Scenario: Peukert’s Law Battery Runtime

Compute true battery runtime and derated capacity under high discharge currents via Peukert’s Law.

  1. Enter your system dimensions, electrical/RF ratings, or environmental conditions.
  2. Evaluate the governing equation: Runtime_hrs = H × [ C_rated / (I_load × H) ]^k; Effective_Ah = I_load × Runtime_hrs.
  3. Inspect the primary design output, supporting allowances, and 3 SVG schematics.
Result: Computes Peukert’s Law Battery Runtime via Runtime_hrs = H × [ C_rated / (I_load × H) ]^k; Effective_Ah = I_load × Runtime_hrs.

Frequently Asked Questions

How does the Peukert’s Law Effective Battery Capacity & High-Current Discharge Runtime Calculator calculate results?

It evaluates Runtime_hrs = H × [ C_rated / (I_load × H) ]^k; Effective_Ah = I_load × Runtime_hrs directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a required dimension or rating?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Does this engineering calculator work offline?

Yes. All calculations run 100% locally in your browser and work offline via the CalculatorGraph PWA.

Science & Engineering · Renewable Energy & Battery Engineering

Peukert’s Law Effective Battery Capacity & High-Current Discharge Runtime Calculator: inputs, method, and how to read the result

Compute true battery runtime and derated capacity under high discharge currents via Peukert’s Law.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Rated Capacity Ah: Nominal battery capacity C in Amp-hours (Ah).
  • Hour Rating Base H: Discharge hour rating H for nominal capacity (20-hr standard).
  • Actual Load Current Amps: Actual continuous discharge current I in Amps.
  • Peukert Exponent K: Peukert exponent k (1.03 LiFePO₄, 1.15 AGM, 1.25 flooded lead-acid).

What the calculation includes

With the default values shown, Peukert Actual Discharge Runtime is 2.01 hours. The calculation follows Peukert’s Law Battery Runtime Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Rated Capacity Ah from 100 Ah to 110 Ah changes Peukert Actual Discharge Runtime from 2.01 hours to 2.25 hours. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses standard NREL, IEEE, ASHRAE, and IRC design equations.
  • Verify final structural, electrical, and mechanical specifications against local building codes.

Scope: Global Engineering & Building Code Standard Check the assumptions and limitations against your situation before relying on the estimate.

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