Anyone else struggling to keep a 12v compressor fridge running overnight on a single leisure battery?

Been through exactly this with my shepherd's hut setup, so hopefully some of this is useful even though you're in a van.

The short answer is: one leisure battery almost certainly isn't enough, especially if it's a standard lead-acid. A compressor fridge will pull somewhere between 30-50Ah overnight depending on ambient temp and how often it's cycling. Most leisure batteries are realistically only giving you 50% usable capacity before you start damaging them, so a 100Ah battery is effectively 50Ah. You can see the problem.

A few things that made a real difference for me:

• Upgrade to LiFePO4 — I went with Fogstar Drift and it transformed things overnight (literally). Full usable capacity and the voltage stays stable so the fridge doesn't work harder than it needs to
• Check your fridge placement — if it's in a warm spot or the ventilation is poor it'll cycle constantly
• Decent solar topped up by driving — even a modest 200W panel keeps things ticking if you're moving regularly

What battery are you currently running and how old is it? An older lead-acid that's been discharged hard a few times could be significantly below its rated capacity by now. Worth load testing it before spending anything.

Also — which fridge? Some of the cheaper 12v compressor units are genuinely inefficient compared to something like a Dometic or Alpicool. Makes a bigger difference than people expect.

Anyone else got thoughts on this? Curious whether others have found a sweet spot with a single battery or whether two is always the answer for overnight use.

Spot on @DodgyHermit — been running a Waeco CFX-35 in my shepherd's hut off a pair of Fogstar Drift 100Ah LiFePO4s and the difference vs a single AGM is night and day, literally 🌙

Key thing people miss: compressor fridges don't just drain steadily, they spike hard on startup — a tired or undersized battery sags under that load and the fridge's low-voltage cutoff kicks in prematurely, so you think you've run out of capacity when you've actually got 40% left.

Minimum I'd suggest for overnight:

• 100Ah LiFePO4 (usable capacity actually matches the rating unlike AGM)
• Decent B2B charger if you're driving to top up
• Set your low voltage cutoff no lower than 12.0v on 12v lithium

Victron BMV battery monitor also changed my life — you can't manage what you can't measure.

Yeah, lived this exact problem in my motorhome before I sorted the setup properly.

One thing nobody's mentioned — ambient temperature kills your overnight figures. My compressor fridge was drawing nearly double in summer parked in direct sun versus a cool night. Worth logging actual draw with a decent battery monitor (Victron BMV-712 is what I use) before throwing more batteries at it.

Also check where the fridge is positioned. Mine was wedged next to the engine bay with zero airflow round the condenser — was working twice as hard as it needed to.

Two Fogstar 100Ah LiFePOs sorted me eventually, but fixing the airflow first made a noticeable difference even before that.

Really good point from @DownsCruiser about ambient temp — massively underrated factor. I'd add that fridge placement matters too. Mine was tucked against the van wall with almost no airflow behind the condenser coils, and it was working far harder than it needed to.

Sorting that alone dropped my overnight draw noticeably before I even touched the battery setup.

For what it's worth, I now run a Victron SmartShunt alongside my Fogstar lithiums, and seeing the actual consumption figures in the app was a real eye-opener — you don't really know what your fridge is pulling until you measure it properly rather than guessing from the spec sheet.

The spec sheet assumes ideal conditions. Real-world draw in a warm van on a summer night can be double what it says on the tin.

Good points all round, but I'd flag one thing nobody's touched on yet: duty cycle.

Most 12v compressor fridges (Waeco, Dometic, CFX range etc.) don't run continuously — they cycle on and off. The quoted amp-draw figures are typically the running current, not the average. Actual overnight consumption depends heavily on how often the compressor kicks in.

On my boat I logged mine with a Victron BMV-712 and was genuinely surprised — real-world draw was roughly 40–60% of what I'd naively calculated assuming constant run time.

Worth doing before you throw money at more batteries. If you haven't got a battery monitor with logging, you're basically guessing.

Related: pre-cooling the fridge before you switch to battery power makes a measurable difference. Thermal mass is your friend overnight.