Battery Life Calculator

- May 10, 2025
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Calculate how long your battery will last based on capacity and current draw.

V
%
? Account for energy loss in the system. Typical values range from 80-95%.

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About Battery Life Calculations

This calculator estimates how long a battery will power a device based on the battery's capacity and the device's power consumption.

Battery Capacity

Battery capacity is typically measured in milliamp-hours (mAh) or amp-hours (Ah), indicating how much current a battery can supply over time. Some batteries are rated in watt-hours (Wh), which accounts for both current and voltage.

Current Draw

Current draw is the amount of electrical current a device requires to operate, measured in milliamps (mA) or amps (A). Power consumption can also be measured in watts (W), which is voltage multiplied by current.

Battery Life Formula

The basic formula for calculating battery life is:

Battery Life (hours) = (Battery Capacity (mAh) × Efficiency) ÷ Current Draw (mA) × (Depth of Discharge ÷ 100)

When using watt-hours and watts, the formula becomes:

Battery Life (hours) = (Battery Capacity (Wh) × Efficiency) ÷ Power Consumption (W) × (Depth of Discharge ÷ 100)

This calculator provides estimates only. Actual battery life may vary based on temperature, battery age, and load conditions.

Understanding the Battery Life Calculator

The Battery Life Calculator is a handy tool that helps you estimate how long your battery will last. It’s designed for anyone who wants to know the runtime of their battery based on its capacity and the current draw of their device. Whether you’re using it for a smartphone, tablet, or any Other gadget, it provides a clear estimate that’s easy to understand.

Why Battery Capacity Matters

Battery capacity tells you how much energy a battery can store. It’s usually measured in milliamp-hours (mAh) or amp-hours (Ah). Here’s why it’s important:

  • Higher capacity means longer usage time.
  • Different devices need different capacities for optimal performance.
  • Understanding capacity helps you choose the right battery for your needs.

Current Draw Explained

Current draw is the amount of power your device needs to operate. It’s measured in milliamps (mA) or amps (A). Knowing the current draw is essential for accurate battery life estimates. Here’s what to consider:

  • High current draw leads to quicker battery depletion.
  • Devices with lower current draw can run longer on the same battery.
  • Power consumption can also be measured in watts (W).

How to Use the Battery Life Calculator

Using the Battery Life Calculator is straightforward. You input the battery capacity, voltage, current draw, and efficiency. It even allows for advanced options, like battery type and depth of discharge. After entering these details, the calculator gives you an estimate of battery life, making it easy to plan your device usage.

Efficiency: What You Need to Know

Efficiency accounts for the energy lost in the system. It’s expressed as a percentage, usually between 80% and 95%. Here’s why it matters:

  • A higher efficiency means more of the battery's energy is used for power.
  • Different devices may have varied efficiency rates based on their design.
  • Understanding efficiency helps you get a more accurate estimate of battery life.

Deep Dive into Depth of Discharge

Depth of discharge (DoD) refers to how much of a battery's capacity you use. It's represented as a percentage and affects battery Health. Using 100% DoD can damage some batteries. Here’s what to remember:

  • A lower DoD can extend battery lifespan.
  • Some batteries, like lithium-ion, can handle deeper discharges better than others.
  • Knowing your battery's DoD is crucial for long-term performance.

The Battery Life Calculation Formula

To calculate battery life, the formula is straightforward. If measuring in mAh, it’s:

Battery Life (hours) = (Battery Capacity (mAh) × Efficiency) ÷ Current Draw (mA) × (Depth of Discharge ÷ 100)

If you're using watt-hours:

Battery Life (hours) = (Battery Capacity (Wh) × Efficiency) ÷ Power Consumption (W) × (Depth of Discharge ÷ 100)

Get the Most Out of the Tool

This calculator provides a useful estimate of how long your battery will last. Keep in mind that actual performance might vary based on factors like temperature and battery age. Using it can help you manage your device's power needs efficiently, ensuring you're never caught off guard by a drained battery.