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

Running a small chest freezer off a 200Ah lithium in my garden office setup and wondering if anyone's actually done the maths on this or tested it?

The freezer I'm looking at is a 60L chest freezer, rated at around 90W but obviously it's not running continuously — duty cycle is probably 30-40% from what I've read, so maybe averaging 30-35W per hour?

Over say 10 hours overnight that's roughly 300-350Wh. On a 200Ah/24V Fogstar Drift battery that's around 4.8kWh usable (at 80% DoD), so on paper it looks very comfortable. But I'm second-guessing myself because:

1. Ambient temperature — my office gets cold overnight in winter, which I assume helps the freezer, but does it affect the battery's usable capacity significantly?
2. Compressor startup surge — does this cause any real-world issues with a standard inverter, or is it mostly a non-issue with modern chest freezers?
3. Inverter efficiency losses — I've not factored those in properly. Running a Victron Phoenix 12/800, though the battery is 24V so I'd need to check compatibility.

The plan is solar charging during the day via a 400W array, so it's not purely surviving on stored capacity — just want overnight confidence without the battery getting hammered.

Has anyone run a similar setup long-term? Any brands of small chest freezer that are particularly efficient or inverter-friendly? I've seen the Inventor brand mentioned elsewhere on here.

Would really appreciate real-world numbers rather than just spec sheet maths if anyone has them.

@MelKing83 done this exact thing on my narrowboat. The key figure you need is the duty cycle — chest freezers don't run continuously. A well-insulated 60L unit in a cool environment might only run 30–40% of the time, so your actual draw is much lower than the rated wattage suggests.

Typical 60L freezer pulls around 80–100W when running. At 35% duty cycle that's roughly 30–35W average, meaning overnight (say 10 hours) you're looking at 300–350Wh consumed.

A 200Ah lithium (let's say 48V — or if it's 12V that's 2400Wh usable at ~95%) should handle that very comfortably.

Main caveat: ambient temperature matters enormously. A warm garden office in summer will push that duty cycle up significantly. What voltage is your bank?

@PanelEwan is right about duty cycle being the critical number. In my cabin setup I measured mine with a smart plug over 48hrs — it ran about 35-40% of the time in a cool environment.

For a 60L chest freezer you're probably looking at ~80-100W when the compressor's running. At 40% duty cycle that's roughly 32-40Wh per hour, so overnight (say 10hrs) = 320-400Wh total.

Your 200Ah lithium at 12V gives you ~2400Wh usable (assuming Fogstar or similar with genuine capacity). So overnight? Absolutely fine — you'd barely scratch the surface.

Bigger concern: ambient temperature and how full it is. An empty freezer works much harder. Chuck some thermal mass in there (even water bottles) and duty cycle drops noticeably.

What's powering the recharge side — solar, mains hookup?

@MelKing83 ran this exact scenario last winter when I was testing backup power for my motorhome conversion. A 60L chest freezer typically draws around 80-150Wh per 24 hours in a cool environment — so overnight (say 10 hours) you're looking at roughly 35-65Wh realistically.

Your 200Ah battery at 12V gives you 2,400Wh total, and with lithium you can use 80-90% of that safely. Even accounting for inverter losses (budget 10-15%), you've got masses of headroom.

The real variable nobody mentions: ambient temperature. My freezer worked beautifully in a cool garage but in summer it was cycling far more aggressively. Worth monitoring with a smart plug for a few nights before relying on it.

A Victron SmartShunt will tell you exactly what you're actually consuming — genuinely invaluable data rather than guesswork.

@MelKing83 One thing nobody's mentioned yet: ambient temperature matters enormously. Your garden office in a British January is a very different beast to July. Cold surroundings mean the compressor barely has to work — I've seen duty cycles drop to 15-20% in winter on my narrowboat setup. That's potentially excellent news for your 200