Short answer: on a 100Ah lithium battery, a full-size 8 to 10 cu ft 12V RV fridge runs about 23 to 35 hours in warm weather with no charging. A small 2 to 5 cu ft fridge runs about 2 to 4 days. A 100Ah AGM battery gives you roughly half those times.
Runtime on one 100Ah battery, by fridge
These figures use the same daily energy numbers as our Solar Sizing tool. Warm weather means about 77°F inside the RV, and hot means 85°F and up. They assume the fridge is the only thing on the battery and nothing is recharging it.
| Fridge | Daily use (warm) | 100Ah lithium | 100Ah lithium, hot | 100Ah AGM |
|---|---|---|---|---|
| Dometic NRX 50S (1.6 cu ft) | 23 Ah | 94 hrs (3.9 days) | 63 hrs | 52 hrs |
| Dometic CRX-1080 (2.7 cu ft) | 27 Ah | 81 hrs (3.4 days) | 54 hrs | 45 hrs |
| Norcold DC105 (5.5 cu ft) | 41 Ah | 53 hrs (2.2 days) | 35 hrs | 29 hrs |
| Norcold N2175 (7.5 cu ft) | 44 Ah | 49 hrs (2 days) | 33 hrs | 27 hrs |
| Norcold N8DC (8 cu ft) | 63 Ah | 35 hrs | 23 hrs | 19 hrs |
| Norcold N10DC (10 cu ft) | 66 Ah | 33 hrs | 22 hrs | 18 hrs |
| Furrion Arctic 10 cu ft | 84 Ah | 26 hrs | 17 hrs | 14 hrs |
| InVision 10.7 cu ft | 95 Ah | 23 hrs | 15 hrs | 13 hrs |
| Norcold N15DC (15 cu ft) | 99 Ah | 22 hrs | 15 hrs | 12 hrs |
| InVision 17 cu ft | 119 Ah | 18 hrs | 12 hrs | 10 hrs |
| Furrion Arctic 16 cu ft | 141 Ah | 15 hrs | 10 hrs | 9 hrs |
Daily use is an estimate. Where the manufacturer publishes daily energy use, we use it. Otherwise we estimate it from rated amp draw and typical run time.
How we figure it
- Find the usable capacity. You can safely use about 90% of a lithium (LiFePO4) battery, so a 100Ah lithium gives you about 90Ah. An AGM should only be run down to about 50%, so a 100Ah AGM gives you about 50Ah.
- Divide by the fridge's daily use. 90Ah ÷ 66Ah a day = 1.36 days, or about 33 hours for a Norcold N10DC.
- Adjust for heat. A compressor fridge can use about 50% more power on a hot day, which cuts runtime by about a third.
Why not just use the amp rating on the label?
A compressor fridge cycles on and off to hold temperature. A fridge rated at 8 amps might average only 2 to 3 amps over a day. Multiplying the label amps by 24 hours can make a 100Ah battery look like it lasts less than half as long as it really does.
How to make your battery last longer
- Add solar. With enough panels, the sun puts back what the fridge uses every day. Our Solar Sizing tool tells you how many watts your fridge needs.
- Charge while you drive. A DC-DC charger tops up your house batteries from the alternator.
- Add battery capacity. Two 100Ah batteries double your runtime. Browse lithium RV batteries or AGM batteries.
- Keep it cool. Park in shade, keep the fridge's vents clear and use eco or night mode if your fridge has one.
- Open the door less. Keep the fridge full and grab what you need at once.
What happens when the battery gets low?
Most 12V fridges shut off before they damage the battery. Norcold's N-series DC fridges, for example, shut off below 10.4 volts and restart once the supply reaches 11.9 volts. A full, closed fridge stays cold for hours, so start the generator, drive or plug in and it picks right back up.