Estimate how long a battery will run a load using battery voltage, amp-hours, watt-hours, kilowatt-hours, load watts, depth of discharge, inverter efficiency, and reserve capacity. This calculator is useful for solar batteries, RV batteries, backup power, UPS systems, off-grid systems, and portable power planning.
Battery energy:
The calculator converts battery voltage and amp-hours into watt-hours, or uses the entered Wh/kWh value.
Usable capacity:
Depth of discharge, inverter efficiency, reserve capacity, and high-load factor are applied to estimate usable energy.
Runtime:
Usable watt-hours are divided by the connected load watts to estimate runtime.
A battery runtime calculator helps estimate how long a battery, battery bank, solar battery, UPS, RV battery, or portable power station can run a load.
It can help with refrigerators, lights, internet equipment, CPAP machines, tools, electronics, pumps, off-grid loads, RV loads, and emergency backup planning.
Your result shows battery runtime in hours and days, total Wh, total kWh, usable Wh, usable kWh, required battery size, batteries needed, load watts, load energy needed, total battery cost, and detailed load row totals.
Convert the battery to usable watt-hours, then divide by the load watts. For example, 900 usable Wh running a 300W load gives about 3 hours of runtime.
Runtime can be lower because of inverter losses, high discharge rates, battery age, temperature, wiring losses, voltage cutoff, and manufacturer discharge limits.
Multiply battery volts by amp-hours to get watt-hours. Then apply usable capacity factors and divide by load watts.
Yes. Lithium, LiFePO4, AGM, gel, and flooded lead-acid batteries can have different usable depth of discharge, voltage curves, and performance under load.