What Size Battery Bank Do I Need for a Refrigerator?
Energy for a few hours of compressor run time is a small bank. The startup watts decide the inverter.
Direct answer: Battle Born's worked example is a refrigerator at 100 W for 5 hours, which is 500 watt-hours, and 500 ÷ 12 = 41.7 Ah at 12 V, about 42 Ah if rounded to the nearest amp-hour (Battle Born battery-bank guide). Honda lists an Energy Star refrigerator at 132–192 running watts and 1,200 starting watts, while Champion lists 150–400 running watts and 800–1,200 starting watts (Honda wattage guide; Champion wattage chart). The inverter surge rating has to clear that startup (Battle Born inverter guide).
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The 100 W example is Battle Born's. Honda and Champion publish different running and starting watts for a refrigerator, so the table keeps them in separate rows.
Swap in Honda's Energy Star running range, still on that 5-hour example: 132 × 5 = 660 Wh and 660 ÷ 12 = 55 Ah; 192 × 5 = 960 Wh and 960 ÷ 12 = 80 Ah (Honda wattage guide).
Champion's running range on the same 5 hours is wider: 150 × 5 = 750 Wh (62.5 Ah) through 400 × 5 = 2000 Wh (166.7 Ah) (Champion wattage chart).
Two days off-grid doubles the example: 500 × 2 = 1000 Wh, and 1000 ÷ 12 = 83.3 Ah (Battle Born battery-bank guide). Strong charging, including solar, shore, alternator, or a generator, can reduce how much you need to store.
Startup is a different column. Honda's start is 1,200 W. Champion's start is 800–1,200 W. The inverter's surge rating has to be at least that highest startup, and its continuous rating has to cover the running watts (Battle Born inverter guide; Honda wattage guide; Champion wattage chart).
If the inverter you buy is 1,000 W continuous, the bank rule is still at least 100 Ah per 1,000 W, even though one 5-hour pass of the 100 W example is only about 42 Ah (Battle Born inverter guide). Use the larger of the energy result and the inverter-capacity result.
A 1,200 W start is 1,200 ÷ 12 = 100 A. That matches one battery's 100 A continuous rating and sits under the 200 A rating allowed for 30 seconds (Battle Born 100 Ah manual). Champion's highest running watts, 400 W, are 400 ÷ 12 = 33.3 A, which is a running current rather than a start.
Lead-acid at about 50% depth of discharge doubles nameplate amp-hours. Twice the example's 41.7 Ah is 1,000 ÷ 12 = 83.3 Ah of lead-acid for that one 5-hour, 100 W case (Battle Born chemistry guide). Lithium in the manual is 100% usable (Battle Born 100 Ah manual).
A fridge is usually one row in a cabin load list. Add the other rows on the battery bank calculator.
Is the 5-hour result the whole bank if the inverter is 1,000 W?
No. The example is about 42 Ah, but a 1,000 W inverter still calls for at least 100 Ah of battery per the Battle Born inverter guide. Keep whichever figure is larger.