Battery Sizing Calculator for Construction Power Planning

Plan battery capacity for site equipment confidently. Adjust voltage, depth limits, temperature, and aging factors. Compare scenarios, then download reports for your crew fast.

Sum of all loads × hours per day.
Highest expected simultaneous power draw.
Pick DC-only if loads bypass an inverter.
Common values: 12, 24, 48, 120 VDC.
Backup duration without charging input.
Lower values extend battery life.
Used only for AC or mixed loads.
Cold reduces usable capacity; add a buffer.
Offsets capacity fade over time.
Covers uncertainty and future load growth.
Typical: 2 V, 6 V, 12 V modules.
Use rated capacity at the relevant discharge rate.
Series sets bank voltage; Ah stays the same.
Parallel increases Ah; voltage stays the same.
Reset
Tip: Use realistic derating for cold sites and long service life.

Example Data Table

Scenario Daily Energy (Wh) Voltage (V) Autonomy (days) DOD Limit (%) Efficiency (%) Result (Ah)
Site Office + Lighting 4,800 24 1.5 50 90 ~ 740
Tools + Chargers 6,500 48 1.0 60 92 ~ 245
Monitoring + Radios (DC) 1,200 12 2.0 70 N/A ~ 286

Values are illustrative. Always verify with equipment specs and manufacturer data.

Formula Used

  • Adjusted daily energy (Wh/day): Eadj = Edaily / η (for AC or mixed loads; for DC-only, η = 1)
  • Autonomy energy (Wh): Eauto = Eadj × Days
  • Base capacity (Ah): Ahbase = Eauto / V
  • Depth-of-discharge adjustment: AhDoD = Ahbase / DoD
  • Final required capacity (Ah): Ahreq = AhDoD × (1+T) × (1+A) × (1+S) where T = temperature derating, A = aging allowance, S = safety margin.

This sizing targets energy autonomy. Confirm surge loads, inverter limits, cable sizing, ventilation, and applicable standards for your site installation.

How to Use This Calculator

  1. List each device and its power draw in watts.
  2. Estimate daily run time and total daily energy (Wh/day).
  3. Enter your target system voltage and autonomy days.
  4. Choose a depth-of-discharge limit based on chemistry.
  5. For AC loads, enter realistic inverter efficiency.
  6. Add temperature, aging, and safety buffers for reliability.
  7. Pick a battery module size, then review series/parallel needs.
  8. Download CSV or PDF to share with your team.
Built for quick site planning; confirm final designs with professionals.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.