Days Without Sun Calculator

Cloudy week coming? See how many days your battery lasts with no charging.

This works out how long your battery can run your daily use with nothing charging it. Everything is worked out in your browser. Nothing is saved or sent anywhere.

1. Your battery

Lithium is often 80 to 90%. Use 50% for AGM.

2. Your daily use

From your own power list or the Camping Trip Power Budget.

3. Results

How it was worked out

    What this does and doesn't tell you

    • Cold weather lowers usable capacity, and hot weather makes the fridge use more. Keep a margin.
    • Even on cloudy days solar usually adds some charge, so this is the worst case.
    • Work on 240V AC wiring, including inverter outputs and mains inlets, must be done by a licensed electrician. For high-current DC gear, follow the maker's installation manual and have an auto electrician check your work if you're unsure.
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