How much does a 12 V compressor cool box (Dometic CFX5, Alpicool) cost to run?
About 0.47p an hour in the UK and 0.33¢ an hour in the US. A 12 V compressor cool box (Dometic CFX5, Alpicool) draws about 45 W for roughly 40% of the time it is switched on, so it averages 18 W. Runs straight off the 12 V socket and skips the inverter, which is why it is the most efficient way to keep food cold off-grid.
What it costs, by how long it runs
| Running for | kWh | UK | US |
|---|---|---|---|
| 10 minutes | 0.003 | 0.08p | 0.06¢ |
| An hour | 0.018 | 0.47p | 0.33¢ |
| An 8-hour night | 0.14 | 3.8p | 2.6¢ |
| A full day (24 hours) | 0.43 | 11p | 7.9¢ |
| A month at 8 hours a day | 4.32 | £1.14 | 79¢ |
UK prices use the Ofgem price cap for 1 October to 31 December 2026 (direct debit, average across England, Scotland and Wales, with no VAT on electricity this winter): 26.32p per kWh (Ofgem). The standing charge of 54.83p a day is paid whatever you run, so it is left out. US prices use the US average residential price for June 2026 from the Energy Information Administration: 18.34¢ per kWh (EIA). Your own tariff is on your bill; scale the figures by it.
Measure your own
These are typical figures for a typical unit. A plug-in energy monitor between the socket and the appliance shows the real watts and adds up the kWh, so after a day or a week you know exactly what it costs on your tariff.
Compared with similar appliances
| Appliance | Average W | UK per hour | US per hour |
|---|---|---|---|
| LED camping lights | 10 | 0.26p | 0.18¢ |
| Festoon / string lights | 15 | 0.39p | 0.28¢ |
| 12 V compressor cool box (Dometic CFX5, Alpicool) | 18 | 0.47p | 0.33¢ |
| Car fridge (12 V, 40 L) | 18 | 0.47p | 0.33¢ |
| Heated jacket battery | 20 | 0.53p | 0.37¢ |
| Heated blanket, 12 V | 23 | 0.59p | 0.41¢ |
| Thermoelectric cool box | 48 | 1.3p | 0.88¢ |
| E-bike charger | 150 | 3.9p | 2.8¢ |
Running it in a power cut
See which power station will run a 12 V compressor cool box (Dometic CFX5, Alpicool), and for how long.
Appliance draw modelled on www.dometic.com. Dometic answers a HEAD request on this page with 404 and a GET with 200, and its /outdoor category now redirects to the homepage, so no stable cooler URL could be confirmed to move to. The range has also moved on from the CFX3 to the CFX5, which draws much the same power — the figures here are for the compressor class rather than one model year.
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