Fridge Run Time Calculator
Planning a camping or 4WD trip means knowing how long your fridge will keep running on your battery setup. Our easy-to-use Fridge Run Time Calculator takes the guesswork out of it by estimating how many hours (or days) your fridge will operate based on your battery size, fridge draw, and other factors.
Whether you’re heading into the outback, spending a weekend off-grid, or simply want peace of mind for your caravan setup, this calculator helps you plan ahead and avoid unexpected warm beers or spoiled food. All you need are a few simple details, and you’ll get an instant estimate to guide your power management decisions.
12 V Fridge Runtime Estimator
Estimates assume healthy battery and ambient conditions; real-world runtime varies with temperature, insulation, and usage.
How to use this calculator
- Select your battery type. AGM/Lead defaults to 50% usable capacity; Lithium defaults to 80%. Choose “Custom” to set your own usable Depth of Discharge (DoD).
- Enter battery capacity (Ah). Use the rated capacity of your house/aux battery (e.g. 100Ah).
- Set usable DoD (%) if you chose “Custom”. This is how much of the battery you plan to use before recharging.
- Enter fridge draw when running (A). Check your fridge specs or measure with a meter (e.g. 4.0A while the compressor is on).
- Enter duty cycle (% running). Approximate percentage of time the compressor is on over an hour (e.g. 40% for mild weather, higher in hot conditions).
- Add other constant loads (A) if any. Think lights, pumps, chargers, trackers, etc. Put 0 if none.
What you’ll see:
- Usable capacity — the Ah you’ve got available based on DoD.
- Avg fridge load — running current × duty cycle.
- Avg total load — fridge load plus any “other” loads.
- Estimated runtime — how long your battery can sustain the average load (hours and days).
Quick example (defaults): AGM 100Ah @ 50% DoD → Usable capacity = 50Ah. Fridge 4.0A at 40% duty → Avg fridge load = 1.6A. No other loads → Avg total load = 1.6A. Estimated runtime ≈ 50 ÷ 1.6 = 31.3 hours (≈ 1.30 days).
Tips for Maximising Your Fridge Run Time
- Choose the right battery: Deep cycle AGM or lithium batteries provide better usable capacity compared to standard starter batteries.
- Keep your fridge in the shade: Reducing heat load helps your fridge run more efficiently.
- Pre-cool before the trip: Run your fridge at home on mains power before heading off to save battery capacity.
- Use a solar panel: A portable or roof-mounted solar panel can extend run time significantly.
- Monitor your voltage: Keeping an eye on battery levels helps prevent over-discharge and extends battery life.
If you’re unsure about your setup, visit Battery Force in-store or contact us online. Our team can recommend the right battery, solar, and accessory solutions to keep your fridge powered up on every adventure.