Battery Life Calculator

Estimate Run Time Based on Capacity, Load, and Efficiency

Battery State Visualization

14.0h

Visualizing scale of run-time (cutoff at 100h)

🔢 Power Specs

How much power your device draws while running.

Recommended: 0.7 (70%) for realistic losses.

Total Duration


Days

0.58

Weeks

0.08

Note: Self-discharge and temperature are not factored in. Real-world mileage may vary!

🎯 A Simple Example: A Portable Fan

You have a small portable fan that runs on 2 AA batteries (total capacity ~2500mAh). The fan motor draws 250mA of current.

Just do this:

1️⃣ Set the Capacity to 2500 mAh.

2️⃣ Set the Load to 250 mA.

3️⃣ Set Efficiency to 0.7 (70%).

4️⃣ Look at the Result: You can expect about 7 hours of cool air! 📐

Pro tip: If your project needs to last for years (like a remote sensor), you need a load in the "microamp" (µA) range—that's 0.001mA!

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Data Source: Peukert's Law / Battery Discharge Theory • Public domain • Solo-developed with AI

Lab Notes

The Reservoir of Power: Why Battery Life Isn't Just Simple Division

The Energy Bucket: Think of a battery like a bucket of water with a tiny hole at the bottom. The "Capacity" (mAh) is the size of the bucket, and the "Load" (mA) is the size of the hole. In 1897, a scientist named Peukert discovered that if you try to drain the bucket too fast, you actually get less energy out of it! In our Digital Laboratory, we account for this "energy tax" by including an efficiency factor. Most batteries can only give you about 70% of their rated capacity before the voltage drops too low for your device to work.

The mAh Mystery: What does "mAh" actually mean? It stands for "milliamp-hours." If a battery is rated at 2000mAh, it theoretically provides 2000 milliamps for one hour, or 1 milliamp for 2000 hours. Historically, the first batteries (like the 1800 Voltaic Pile) were unstable and unpredictable. It took over a century of chemical engineering to create the standardized, reliable energy cells we have today. We use these modern standards to help you plan your projects so you aren't left in the dark.

Design for Longevity: Why does your TV remote last for years while your phone dies in a day? It’s all about the "quiescent current"—the tiny amount of power a device sips when it’s supposed to be off. Engineers spend thousands of hours optimizing this math to make sure smoke detectors and medical implants stay powered for as long as possible. We bridge the gap between high-level power analysis and your DIY workbench by giving you a realistic estimate of your project's "field life."

Bridging Data to the Present Day: In the Lab, we believe that understanding power is the key to sustainable invention. As you adjust the load, you can see exactly how much "run-time" you gain by choosing more efficient components. By visualizing the battery as a dynamic reservoir, we show you the trade-off between performance and longevity. Whether you're building a robot, a portable weather station, or just curious about your flashlight, our calculator provides the rigorous logic needed to manage your energy budget.

🐾 From the Lab Cat's Energy Conservation Division:

I have Conducted extensive research into potential energy storage, specifically in the form of "The Nap."

  • High-Drain Events: The "Zoomies" is a high-drain event that consumes approximately 95% of my current capacity in 3 minutes. I require an immediate 4-hour recharge cycle (napping in a sunbeam) to recover.
  • Low-Power Mode: I spend 85% of my day in "Low-Power Mode," where my only current draw is maintaining a slight tail-twitch to indicate I am still listening to your conversation.
  • Efficiency Tax: I have discovered that 30% of all treats are lost to "Floor-Friction" and "Under-Appliance Sequestration." This must be factored into my daily nutrition budget.

Current Status: Battery at 12%. Engaging sleep-mode now. 🐈

In short: These tools are for education and curiosity only. Always verify information independently and consult professionals before making important decisions.

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