Running Air Conditioning in a Campervan: What You Need
Running air conditioning in a campervan is possible — but it demands more from your electrical system than almost any other appliance. Here is what each approach actually requires.
The challenge with campervan air conditioning
Air conditioning has two power-hungry moments: startup surge and sustained running draw. A portable 1,000W AC unit may pull 2,500–3,000W when the compressor kicks in, then sustain 900–1,100W for the duration. Running that for 8 hours off battery would consume 7,200–8,800Wh — far beyond what most campervan battery banks provide.
This makes AC fundamentally different from other appliances. A 1,500W kettle draws that only for 3 minutes to boil. An AC unit draws 1,000W continuously for hours.
Option 1: 12V compressor air conditioners (battery-powered)
Dedicated 12V DC compressor units for campervans and vans are now widely available. These are designed to run directly from a 12V leisure battery system without an inverter.
How they work: A variable-speed 12V compressor (similar to a 12V fridge compressor but scaled up) runs the refrigeration cycle. Because they run on DC, there is no inverter conversion loss.
Popular UK-available options:
| Unit | Power draw | Cooling output | Suitable battery bank |
|---|---|---|---|
| Webasto Air Top 2000 (air heater, not AC) | — | — | — |
| EcoFlow Wave 2 (with 12V DC cable) | ~330W average (variable) | 5,100 BTU | 200Ah LiFePO4 minimum |
| Dometic RTX 1000 | ~200–400W (variable) | 950W cooling | 200Ah LiFePO4 |
| Dometic RTX 2000 | ~300–600W (variable) | 2,000W cooling | 300Ah+ LiFePO4 |
| Fogatti Camper AC | ~280W average | Small van | 200Ah LiFePO4 |
Battery requirement example (EcoFlow Wave 2 at 330W average):
- 8 hours cooling: 330W × 8h = 2,640Wh = 220Ah at 12V
- A 300Ah LiFePO4 provides ~260Ah usable (at 90% DoD) — enough for one night
- Solar recharge during the day can extend this significantly
These units are the most practical battery-powered AC for campervans. They avoid the need for a large inverter and are purpose-built for van use.
Option 2: 230V portable air conditioners via inverter
Standard portable air conditioners (the floor-standing units with a duct hose out the window) run from 230V mains. You can run them from an inverter — but the numbers are demanding.
A typical portable AC:
- Startup surge: 1,500–3,000W (compressor startup)
- Sustained draw: 900–1,500W
Inverter required: 2,000W minimum; 3,000W recommended for reliable startup. A Victron MultiPlus 12/3000 or similar.
Battery draw (900W AC unit, 8 hours):
- 900W ÷ 12V × 1.15 (inverter losses) = ~86A continuous
- 8 hours: 688Ah draw — this exceeds any realistic campervan battery bank
Realistic use case: A 230V portable AC is only practical in a campervan when connected to hook-up (EHU) at a campsite. On hook-up, a 3kW supply can run a 900W unit comfortably. Off hook-up, battery capacity makes extended cooling impossible.
Option 3: Roof-mount split air conditioners
Some larger campervans and motorhomes fit roof-mount split AC units (similar to domestic mini-splits but 12V or 24V compatible). These are more efficient than portable units but require:
- 24V or 48V battery system for larger units
- Professional fitting through the roof
- Higher upfront cost (£800–2,500 installed)
For a converted van, this is unusual unless you have a high-voltage battery system (24V/48V).
Option 4: Hook-up only
The simplest approach: bring a standard portable AC unit (£150–350) and only run it when connected to campsite hook-up. Pair this with insulation and ventilation (roof vent fans such as MaxxAir or Dometic Fan-Tastic) for off-grid use.
Roof vent fans draw only 3–5A at 12V — trivial for a leisure battery — and can make a well-insulated van comfortable in temperatures up to about 28°C without refrigeration.
What about car air conditioning (engine bay compressor)?
Your van's factory air conditioning (if fitted) is driven by a belt from the engine — it only cools when the engine is running. Some van lifers run the engine for 15–20 minutes to pre-cool the van before bed. This is not free (fuel cost, idle emissions) but it is simple.
Dometic FreshJet / RoofAir roof units for motorhomes require shore power or a generator — they are 230V units and draw 500–900W sustained.
Realistic recommendations by system size
| Battery bank | Solar | Recommended approach |
|---|---|---|
| Under 100Ah | Any | Roof vent fan only; hook-up for AC |
| 100–200Ah LiFePO4 | 200W+ | 12V compressor AC (short sessions), fan otherwise |
| 200–300Ah LiFePO4 | 400W+ | 12V compressor AC overnight (one night per charge cycle) |
| 300Ah+ LiFePO4 | 600W+ | 12V compressor AC overnight with solar top-up |
| Any + hook-up | — | 230V portable AC on hook-up, 12V fan off-hook-up |
FAQ
Can a 1,000W inverter run a portable air conditioner?
No — the startup surge of most portable AC units (1,500–3,000W) will trip a 1,000W inverter immediately. You need 2,000–3,000W continuous with high surge tolerance.
How long can I run the EcoFlow Wave 2 on a 200Ah LiFePO4?
At 330W average draw from a 200Ah (12V) battery: 200Ah × 12V × 0.9 DoD ÷ 330W ≈ 6.5 hours. Adequate for most UK summer nights.
Is van AC worth it for UK camping?
The UK rarely exceeds 30°C, and most campervans have adequate ventilation with a roof fan and good insulation. Many van lifers camp comfortably without AC. For European travel (Spain, France, Portugal in summer), the equation changes — a 12V compressor unit becomes worthwhile.