This is a simple tool to help calculate the estimated run-time* of your battery or battery bank under a given load. By entering the Rated Battery Capacity, measured in amp hours (symbol: Ah) and applied load i.e. Discharge Rate, measured in amperage or amps for short (symbol: A), you can calculate the Actual Battery Capacity at that load plus how much time it takes to discharge to the batteries to safe levels 25% - 50%, (green and yellow) and to the levels at which you may be damaging the battery (orange, red, deep red).

The calculator also takes into consideration PEUKERT'S Law.
If you happen to have the manufacturers Peukerts Number then you can enter it.
Otherwise it's set to 1.1

For a lead–acid battery, the value of is typically between 1.1 and 1.3.
For VRSLAB AGM batteries, it generally ranges from 1.05 to 1.15.
For GEL batteries from 1.1 to 1.25.
For Flooded batteries commonly known as sealed batteries, 1.2 to 1.6.

* Due to factors such as age, make and temperature please note that run-times are estimates.

What’s New

Version 1.0.4

This app has been updated by Apple to use the latest Apple signing certificate.

- Fixed display issues.

Ratings and Reviews

5.0 out of 5
1 Rating

1 Rating

B-Phone ,

Simple & Useful!!

Handy little app for calculating estimated battery life for a given amp draw. Great if you are setting up a solar grid or have an electric vehicle that runs off of good 'ol lead batteries. For me, it helped me with my electric boat!

App Privacy

The developer, Kris Arndt, has not provided details about its privacy practices and handling of data to Apple.

No Details Provided

The developer will be required to provide privacy details when they submit their next app update.


  • Family Sharing

    Up to six family members will be able to use this app with Family Sharing enabled.

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