Electric cool box on hook-up or battery
A guide, not advice. Check your kit maker's figures before you buy or pack.
The calculator needs JavaScript. The worked example, sum and figures below show exactly how it works, so you can do it yourself. A guide, not advice.
Short answer
Enter the cool box's daily energy use from its label or your own measurement. The calculator totals the trip energy and compares it with figures you enter for a battery or hook-up. Use energy in watt-hours (Wh); a compressor's rated watts do not show how much it uses over a day because it cycles on and off.
Worked example
| You enter | Value |
|---|---|
| Cool box energy use per day from its label or your measurement | 300 Wh/day |
| Days to run it | 3 |
| Battery usable energy capacity | 1,000 Wh |
| Share of battery capacity you plan to use | 80% |
| Hook-up energy available for the cool box | 1,500 Wh |
Plan for 900 Wh (0.90 kWh) of energy
| Result | Value |
|---|---|
| Energy for the trip | 900 Wh (0.90 kWh) |
| Battery check | Entered battery capacity is below the calculated energy, before other loads and losses. |
| Hook-up check | Entered hook-up energy covers the calculated cool box energy. |
Show the working
- Trip energy: 300 Wh/day × 3 days = 900 Wh
- Battery allowance: 1000 Wh × 0.008 = 8 Wh
- Hook-up energy entered: 1500 Wh
How it works
- Trip energy = the cool box's stated or measured daily energy use × days
- Battery usable energy = battery capacity × the share you choose to use
- Compare trip energy with the supply's available energy
Use energy in Wh from the maker or your own measurement. Compressor cool boxes cycle on and off; rated input power is not the same as energy used per day.
Actual battery delivery, inverter losses, other appliances and temperature can affect runtime. This tool does not assess electrical safety or compatibility.
Our figures (adjustable)
These are our planning allowances and, once checked, typical figures with their sources. They aren't facts about your kit: change any of them in the calculator.
This calculator has no built-in defaults: every figure comes from you or your kit's own label.
What to buy
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FAQs
Can I use the cool box's rated watts?
Use a stated or measured energy figure in Wh per day if available. Rated input power alone does not account for how long a compressor runs.
Does a battery match guarantee the cool box will run?
No. Other loads, conversion losses, temperature, battery condition and electrical compatibility affect real use. Follow the maker's instructions and campsite rules.
Guides that use it
Electric cool boxes explained
Electric cool boxes explained: check power input, capacity and running time before you travel, and plan a backup for keeping food cold.