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UPS Battery Runtime Energy Estimate

An idealized energy estimate from nominal battery energy, user-entered usable fraction, efficiency, and load. Actual runtime depends on manufacturer discharge curves, cutoff voltage, discharge rate, temperature, battery condition, and UPS behavior.

Inputs

Range: at least 0.01 V

Enter the nominal DC voltage of the complete battery string at the stated operating point. Actual runtime requires the manufacturer discharge curve.

Range: at least 0.01 Ah

Example starting value: 100 Ah. Replace it with the battery or string nameplate capacity.

Range: 0–1

Example starting value: 0.80. Use the usable-energy assumption from the battery/UPS study.

Range: 0.01–1

Example starting value: 0.85. Replace it with the UPS or converter efficiency for the operating point.

Range: at least 0.01 W

Example starting value: 300 W. Replace it with the actual DC-equivalent load.

Result

Nominal battery energy
2,400.00 Wh
Idealized runtime estimate
5.44 h
Estimated usable energy
1,632.00 Wh
Estimated usable energy
\mathrm{Nominal\ battery\ energy} \cdot \mathrm{User\-entered\ usable\ energy\ fraction} \cdot \mathrm{User\-entered\ conversion\ efficiency}
2400 \cdot 0.8 \cdot 0.85
Idealized runtime estimate
\frac{\mathrm{Estimated\ usable\ energy}}{\mathrm{DC\-equivalent\ load\ (W)}}
\frac{1632}{300}

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