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POWER / 12V FRIDGES

How long will a 12V fridge run on a battery? Work it out in seconds.

Choose your fridge and battery to see roughly how long it will keep running, with or without solar. Fridge figures come from the makers’ own published averages, with their test conditions shown.

Independent Seekstead calculator · Australia
Maker figures checked 6 October 2026

12V FRIDGE BATTERY CALCULATOR

Your own allowance. Makers test in mild, steady conditions; real camps are hotter and busier.

Your battery

Solar (optional)

Solar figures allow for real-world losses (70% of the panel’s rating). Cloudy days put back far less.

Your fridge should run for about

—

Same fridge, other battery sizes

    A theoretical estimate from the maker’s average and the assumptions shown, not a guarantee. Heat, how often you open the lid, warm food and battery age all change it.

    QUICK ANSWERS

    How long will a 12V fridge run on a 100Ah lithium battery?

    For the fridges in our calculator, about 2 days 9 hours to 6 days 23 hours without solar.

    With 80% of a 100 Ah lithium battery usable (80 Ah), the run time depends on how much the fridge uses a day. The makers’ published averages for the fridge-only models in our list range from about 11.5 to 33.6 Ah a day under their test conditions. Dual-zone fridge-freezers running one side as a freezer use much more, about 42 to 70 Ah a day. Hot weather, a freezer setting or a busy camp can use noticeably more, so use the calculator with an allowance for your conditions.

    How long will a car battery run a 12V fridge?

    Not for long, and you shouldn’t rely on it.

    A car’s starting battery is built to give a big burst to start the engine, not to be run down day after day. Most 12V fridges have battery protection that switches the fridge off early so you can still start the car. As an example, if you could use 30% of a 60 Ah starting battery, that’s about 18 Ah, which is 23 hours for a fridge using 19 Ah a day. For overnight stops and longer trips, a separate deep-cycle (auxiliary) battery is the usual answer.

    How many amps does a 12V fridge draw?

    A few amps while the compressor runs, but much less on average.

    A compressor fridge switches on and off to hold its temperature, so the number that matters for your battery is its average draw over a day, not the running current. For example, Bushman lists the Roadie SC15 at “2A to 4.5A” while running, but “Average 0.58 Amp/hr over 24hrs” on average (25º ambient, 4º fridge, 12V system). Look for an average figure in amp-hours per hour or per 24 hours, with the test temperature beside it.

    What size battery do you need to run a 12V fridge?

    Daily use × days between charges ÷ the usable share of the battery.

    For a fridge using 19 Ah a day and two days between charges, that’s 38 Ah of usable energy: about 48 Ah of lithium (using 80%) or 76 Ah of AGM (using 50%). Add a margin for hot weather, and remember solar or driving can top it up.

    How solar changes the answer

    Solar can cover a fridge on a sunny day, but plan for cloudy ones.

    A rough guide is panel watts × good sun hours × 0.7 (for real-world losses) ÷ 12 volts. A 200 W panel with 5 good sun hours puts back about 58 Ah, which on a sunny day can cover a fridge using 19 Ah. Good sun hours vary with season, location and shade, and cloudy days can drop to a fraction of that, so your battery still has to carry you between sunny days.

    Why your real result will differ

    • Heat. Makers test at a set outside temperature (often 25°C or 32°C). Hotter days mean more compressor time.
    • Opening the lid and adding warm food or drinks.
    • Insulation and shade: a fridge cover and keeping it out of the sun both help.
    • Set temperature: a freezer setting uses far more than a fridge setting.
    • Battery age and wiring: older batteries hold less, and thin or long cables lose voltage.

    HOW WE WORK IT OUT

    Run time = usable battery (amp-hours) ÷ (the fridge’s daily use − what solar puts back). The fridge figures are each maker’s published average, converted to amp-hours a day at 12 volts. The usable share of each battery type and the solar allowance are Seekstead’s assumptions, shown above, and you can change them to match your own gear.

    Maker figures used

    • Bushman Roadie SC15 (15 L): “Average 0.58 Amp/hr over 24hrs” (25º ambient, 4º fridge, 12V system), about 13.9 Ah a day. Source
    • Dometic CFF 12 (13 L): “0.48 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 11.5 Ah a day. Source
    • Dometic CFF 18 (19 L): “0.66 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 15.8 Ah a day. Source
    • Dometic CFF 45 (44 L): “0.87 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 20.9 Ah a day. Source
    • Dometic CFX5 25 (25 L): “0.77 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 18.5 Ah a day. Source
    • Dometic CFX5 35 (36 L): “0.77 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 18.5 Ah a day. Source
    • Dometic CFX5 45 (46 L): “0.76 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 18.2 Ah a day. Source
    • Dometic CFX5 55 (55 L): “0.87 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 20.9 Ah a day. Source
    • Dometic CFX5 55IM (icemaker on) (55 L): “1.21 Ah/h” (Ambient 32°C, internal 4°C, icemaker on (maintenance)), about 29 Ah a day. Source
    • Dometic CFX2 37 (37 L): “0.78 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 18.7 Ah a day. Source
    • Dometic CFX2 45 (45 L): “0.86 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 20.6 Ah a day. Source
    • Dometic CFX2 57 (57 L): “0.89 Ah/h” (ambient 32°C, internal 4°C, 12 V DC), about 21.4 Ah a day. Source
    • Evakool 40L Platinum Drawer (40 L): “Set on 2ºC - 1.2 A/Hr” (average over 24 hours at 32ºC, set on 2ºC), about 28.8 Ah a day. Source
    • myCOOLMAN 30L Transporter (30 L): “Power Consumption 0.8 Ah” (average per hour; DC12V set at 5°C, 32°C ambient), about 19.2 Ah a day. Source
    • myCOOLMAN 44L single zone (44 L): “Power Consumption 0.8 Ah” (average per hour; DC12V set at 5°C, 32°C ambient), about 19.2 Ah a day. Source
    • myCOOLMAN 60L single zone (60 L): “Power Consumption 0.8 Ah” (average per hour; DC12V set at 5°C, 32°C ambient), about 19.2 Ah a day. Source
    • myCOOLMAN 105L single zone (105 L): “Power Consumption 1.4 Ah” (average per hour; DC12V set at 5°C, 32°C ambient), about 33.6 Ah a day. Source
    • Dometic CFX5 75DZ (75 L): “2.45 Ah/h” (4°C large zone, −15°C small zone, 32°C ambient), about 58.8 Ah a day. Source
    • Dometic CFX5 95DZ (94 L): “2.83 Ah/h” (4°C large zone, −15°C small zone, 32°C ambient), about 67.9 Ah a day. Source
    • Dometic CFF50LPDZ (50 L): “1.75 Ah/h” (4°C fridge, −15°C freezer, 32°C ambient), about 42 Ah a day. Source
    • Dometic CFF 70DZ (70 L): “2.9 Ah/h” (4°C fridge, −15°C freezer, 32°C ambient), about 69.6 Ah a day. Source
    • Evakool 50L Down Under II (50 L): “1.8 A/hr” (average over 24 hours at 32°C, one zone at 2°C, one at −16°C), about 43.2 Ah a day. Source
    • Evakool 65L Down Under II (65 L): “1.9 A/hr” (average over 24 hours at 32°C, one zone at 2°C, one at −16°C), about 45.6 Ah a day. Source
    • Evakool 80L Down Under II (80 L): “2.0 A/hr” (average over 24 hours at 32°C, one zone at 2°C, one at −16°C), about 48 Ah a day. Source