Anyone know if a 200Ah lithium battery will run a small chest freezer overnight?

Running a small chest freezer off a single 200Ah LiFePO4 — has anyone actually done this long-term rather than just theoretically?

I've got a Fogstar Drift 200Ah sitting in my setup and I'm trying to work out whether it's sensible to run a small chest freezer (thinking along the lines of a 60-70 litre unit) through the night purely on battery, with solar doing the heavy lifting during the day.

The numbers look okay on paper. A decent chest freezer in a cool environment might draw 80-100W when compressing, but the duty cycle is what really matters isn't it — if it's only running the compressor 30-40% of the time, you're looking at maybe 200-300Wh overnight across say 10 hours. That's well within what a 200Ah lithium can deliver, even keeping above the 20% state-of-charge floor.

But real-world is always messier. A hot summer night, a warm ambient temperature in whatever outbuilding it's sitting in, or a freezer that's been opened repeatedly during the day — all of that will shift the numbers considerably I'd imagine.

My specific concerns:

• Startup surge — will my Victron inverter handle the compressor kick without throwing a fault?
• Ambient temperature — the battery lives in an uninsulated lean-to, so nights can get properly cold in winter
• Which chest freezer — are there brands notably more efficient than others at that small end?

Anyone running something like this who can share actual consumption figures rather than spec sheet guesses?

@MoorHamish done exactly this in my static caravan — Fogstar Drift 200Ah running a small Icemaster chest freezer and it's fine overnight, but "overnight" does a lot of heavy lifting as a word depending on how cold your ambient temp is 😅

The freezer cycles on and off rather than running constantly, so actual draw is way less brutal than the nameplate suggests — mine pulls maybe 30-40Ah over a full night once it's already down to temp.

The killer detail nobody mentions: pre-chill it on mains first before switching to battery, otherwise you're paying the thermal debt yourself. Found that out the expensive way.

@MoorHamish I've been curious about this exact scenario for my static caravan setup. What's your freezer's rated wattage and how are you planning to charge the Fogstar between cycles?

The bit I keep getting stuck on is the compressor start surge — some smaller chest freezers pull 3-4x running watts on startup. Has yours got a soft-start compressor or is it an older style?

Also worth knowing: are you aiming to run this fully off-grid overnight with no solar top-up, or is there grid available as backup? That changes the usable capacity calculation quite a bit, especially if you're only drawing to 80% SoC to protect the cells long-term.

@HeatherWalker's experience sounds promising — would be interested to hear what ambient temperatures your caravan sees, as that'll affect compressor duty cycle significantly.

@MoorHamish ran this exact experiment in my shepherd's hut last winter, albeit somewhat accidentally when the solar panels were buried under three inches of Shropshire snow for four days.

The short answer: yes, but the maths matters enormously. A typical small chest freezer pulls maybe 80-150W at the compressor, but the duty cycle is your friend — it's not running constantly. Realistically you're looking at 30-50Wh per hour averaged out.

On a 200Ah LiFePO4 you've got roughly 2,000Wh usable (assuming 10% buffer). That's comfortably 40+ hours even before your panels contribute anything.

The killer variables nobody mentions:

• Ambient temperature (warmer = compressor works harder)
• How full the freezer is (fuller = more thermal mass = better)
• Lid discipline — every peek costs you

@TelHall — rated wattage is almost meaningless here; find the annual kWh consumption on the label instead.

Done this for two winters with a chest freezer on my garden office setup.

Key thing people miss — it's not just the wattage, it's the duty cycle. A chest freezer typically runs 20-40% of the time depending on ambient temp. Winter makes it easier; summer kills you.

Real-world numbers from mine: ~150-180Wh per 24hrs in a cool space. A 200Ah LiFePO4 (at 12V) gives you roughly 2kWh usable at 80% DoD — so you've got plenty of headroom overnight, assuming your BMS doesn't have issues.

Watch the startup surge though. Cheap inverters can fault on compressor kick-in.

@CopperWelder accidental experiments are sometimes the best data tbh.

Main risk is a cloudy week with no recharge — that's where people come unstuck. Have a backup plan.