Battery Backup Calculator

Every mobile robot eventually stops in the middle of a test because the battery ran out sooner than expected. The Battery Backup Calculator is a small tool we built so that question gets answered before the battery is bought, not after.

You list what runs on the robot (computer, sensors, motor drivers, motors, lights) with the voltage each device uses and three currents: idle, typical and peak. You describe the battery pack. The calculator converts everything to watts, works out the current drawn from the pack, and reports the runtime for each case, together with a warning when the peak draw is more than the pack is rated to deliver.

What it is good for

• Choosing the capacity of a new pack from a target runtime.
• Checking whether a pack's C-rating can handle motor start-up and climbing.
• Seeing which device dominates the power budget, so you know where to save energy.
• Comparing a 12 V and a 24 V system for the same robot.

How it works

Power is the one quantity you can add up safely across devices at different voltages, because a DC-DC converter passes power through (minus a little loss) while changing voltage and current. The calculator sums the power of all devices, divides by the pack voltage to get the pack current, and divides the usable charge (capacity times depth of discharge) by that current to get hours. The tool page shows every formula and a fully worked example.

Who it is for

Students and makers building their first rover, research teams sizing a pack for a new platform, and anyone who wants a quick sanity check before ordering parts. It runs in the browser, needs no account, and nothing you type leaves your computer.

Open the Battery Backup Calculator, then read the guides below for the details: real current measurement, C-ratings, battery chemistries and safety.