Energy converter

Battery Run Time Calculator

Estimate how long a battery will power your electrical load given its capacity and discharge settings.

How Battery Run Time works

Battery run time represents how long a storage cell can power a device before depletion. It is calculated by dividing the usable energy capacity of the battery by the power consumption of the connected load.

Depth of Discharge (DoD) is crucial. Discharging batteries completely (100% DoD) can degrade them quickly. Most lead-acid setups operate at 50%-80% DoD, while lithium batteries safely run at 90%-100%.

Formula

1Usable Wh = Capacity(Ah) × Volts(V) × DoD(%) ÷ 100

2Run Time (Hours) = Usable Wh ÷ Load(Watts)

DoD is the percentage of capacity that is usable.

Battery Run Time conversion table

Reference Table6 rows

Estimated run times for a 12V 100Ah battery (80% DoD, 960 Wh usable).
Load Power (Watts)↕	Estimated Run Time (Hours)↕	Typical Device Match↕
10 W	96.0 hours	LED Bulb / Router
50 W	19.2 hours	CPAP / Laptop
100 W	9.6 hours	Smart TV / Gaming Console
250 W	3.84 hours	Slow Cooker / Desktop Workstation
500 W	1.92 hours	Sump Pump
1,000 W	57 minutes	Microwave (continuous)

💡 Click any row to auto-fill the calculator aboveClick column headers to sort

FAQ: Battery Run Time

How do you calculate battery run time?

Multiply the battery capacity in Ampere-hours (Ah) by its voltage (V) to find total Watt-hours (Wh). Multiply by the depth of discharge percentage (DoD) to find usable Wh, and then divide by the load's power consumption in Watts.

What is DoD (Depth of Discharge)?

Depth of Discharge indicates how much battery capacity can be used before recharging without causing internal damage. For example, an 80% DoD means you use 80% of the total capacity, keeping 20% in reserve.

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