Robot Battery Life
Runtime from battery charge and current draw.
Formula
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Example
Q=5 Ah, I=2.5 A: t = 2 h
How it works
A battery’s capacity, measured in amp-hours (Ah), tells you how much charge it can deliver, while the current draw, in amps, tells you how quickly the robot uses that charge. Dividing charge by current gives the time the battery can last because amp-hours is essentially current time , so time = charge current . This is a simple ideal estimate that assumes the current stays roughly constant and the battery can deliver its full rated capacity.
When to use it
Use this when estimating how long a robot, drone, or other battery-powered device can run at a steady current draw. It is especially useful for quick planning, comparing batteries, or checking whether a battery size is sufficient for a project.
Worked example, step by step
Given: Q = 12 Ah I = 3 A Use the formula: t = Q / I t = 12 / 3 t = 4 h Final answer: the robot can run for 4 hours.
Common mistakes to avoid
- Using milliamps and amp-hours without converting to matching units
- Forgetting that higher current means shorter runtime
- Treating the result as exact even though real battery life changes with load, battery condition, and efficiency
Did You Know?
Real runtime falls short of this because motors surge current during acceleration and climbing.
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