Anyone running a full 12v compressor fridge in a camper without shore power — what's your actual daily draw?

Fitting out a mate's Transit LWB at the moment and he wants a proper compressor fridge (looking at the Dometic CFX3 45) running purely off solar + leisure battery. No hook-up, mostly wild camping in Scotland and Wales.

I've done similar on my shepherd's hut setup — 200Ah Fogstar lithium, pair of 100W Renogy panels, Victron MPPT — and that handles a small 12v coolbox fine. But a full compressor fridge is a different beast, especially in summer when it's cycling more often.

Seen estimates anywhere from 30–60Ah per day for a 45L compressor fridge depending on ambient temp and how full you keep it. That's a massive range and hard to size for properly.

Anyone got real-world numbers from a similar setup? And worth going 200Ah or jumping straight to 300Ah for a van that'll do week-long trips off-grid?

GeorgeHarris | 847 posts

@CrispyWelder good choice on the CFX3 45 — cracking bit of kit. Real-world draw in a UK summer is roughly 30-40Ah per day once it's up to temperature, though that climbs noticeably if he's opening it constantly or the ambient temps spike. Cold pre-loading food before a trip makes a genuine difference.

For a Transit LWB wild camping setup I'd suggest a minimum 200Ah lithium (not AGM — the usable capacity difference is significant) paired with at least 200W of solar. That should keep him comfortable through reasonable UK summer days.

Worth mentioning — insulating around the fridge itself and keeping it out of direct sun massively reduces duty cycle. Mine sits in a shaded cabinet and I reckon it saves me 10-15Ah daily easily.

What battery chemistry is he planning?

CamperRachel | 312 posts

Running a CFX3 35 myself so fairly similar ballpark. In practice I'm seeing roughly 25-35Ah per day in decent UK summer temps, but that crept up to nearly 50Ah during last August's heatwave when I was parked on an exposed site with full sun hitting the van sides. Ambient temp inside the van makes a massive difference — if your mate can position the fridge somewhere with decent airflow around the condenser coils, it'll thank him for it.

Also worth factoring in that first hour after loading warm food/drinks — it hammers the battery pulling everything down to temperature.

What leisure battery setup is he planning? That'll really dictate whether the solar spec is adequate more than the fridge draw itself. 😊

SophieHobbs74 | 203 posts

Different context from a campervan (I run mine in a shepherd's hut) but my CFX3 55 pulls noticeably more in winter when ambient temps drop and the compressor works harder to maintain differential — counterintuitive but worth factoring in if he's planning year-round use.

On the solar side, a single 200W panel will struggle on overcast UK days. I'd push for at least 400W and pair it with a decent MPPT — Victron SmartSolar being the obvious choice. A 100Ah Fogstar Drift LiFePO4 transformed my overnight figures compared to my old AGM too.

The CFX3's built-in battery protection is useful but I wouldn't lean on it as your main safeguard.

Gazza | 1,204 posts

Worth flagging something nobody's mentioned yet — ambient temperature inside the van matters massively. Parked in full sun, that CFX3 is fighting against a 40°C+ interior even on a mild UK day. I learned this the hard way in my Transit conversion; stuck a silver thermal windscreen wrap across the rear windows and my fridge draw dropped noticeably overnight.

Also for @CrispyWelder — whatever daily Ah figure you land on, double it for your battery sizing. Fogstar Drift 100Ah LiFePO4 is what I run for emergency backup at home but same logic applies in a van; you want real usable capacity, not half a lead-acid being nursed along.

Victron SmartShunt is worth every penny too — stops you guessing and actually tells you what's happening.