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

Got a garden office setup with a 200Ah LiFePO4 (Fogstar Drift) and a 400W solar array. Works great for lighting, laptop, phone charging etc but I'm thinking about adding a small chest freezer for the warmer months.

Looking at something like a 30-35L chest freezer — the efficient ones that pull around 60-80W when running but obviously cycle on and off through the night.

My rough maths:

• Say it averages 30-35W over 8 hours overnight = roughly 240-280Wh
• At 12V that's around 20-23Ah which seems fine

But that's assuming nothing else is drawing power and the freezer isn't working overtime in summer heat. The office isn't insulated brilliantly so ambient temps could be pushing the compressor harder.

Has anyone actually run a chest freezer off a similar sized bank? A few things I'm uncertain about:

1. Startup surge — will the inverter handle it without tripping? I've got a Victron 12/1600
2. Does a poorly insulated space massively affect duty cycle in practice?
3. Worth pre-cooling the freezer contents during the day when solar is generating, to reduce overnight load?

Not planning to run it 24/7, more like weekends when I'm actually using the space. Tempted to just try it but don't want to hammer the battery unnecessarily if the numbers don't actually stack up in real life.

Anyone done similar? Particularly curious if anyone's measured actual overnight consumption with a Shelly plug or similar before committing.

@Rodney depends massively on the freezer. A decent small chest freezer (50-60L) only pulls maybe 80-100Wh per day once it's at temp — they're surprisingly efficient because cold air doesn't fall out when you open the lid like an upright.

Your 200Ah Fogstar gives you roughly 2kWh usable (assuming 100% DoD on LiFePO4). Even a greedy freezer doing 150Wh/day is nothing.

The real question is ambient temp — stuck in a garden office in summer it'll work harder. Also worth checking the minimum operating temp of the compressor, some cheap ones struggle below 10°C which matters in winter.

I'd go for it. Running a chest freezer in my motorhome off similar capacity, no issues.

@DownsCruiser is right about the compressor duty cycle being the key variable. What I'd add — from running a small chest freezer in my shepherd's hut — is that ambient temperature matters enormously. Mine barely touches the battery in winter but in a hot summer it was cycling far more aggressively.

Also worth checking the startup surge on whatever freezer you're looking at. Some smaller units spike quite high on compressor kick-in, and your inverter needs to handle that comfortably.

With a Fogstar Drift 200Ah you've got roughly 2.56kWh usable (assuming 80% DoD), so overnight power shouldn't be the problem — it's whether your 400W array can replenish it the next day. In a UK winter that could be tighter than you'd think. 📊

Worth adding from my boat experience — ambient temperature makes a huge difference to your numbers. In summer when it's warm overnight, that freezer will cycle far more frequently than the figures @DownsCruiser and @TinaHenderson are quoting.

On my narrowboat I run a 70L chest freezer and summer nights can easily double the draw compared to winter. Your 200Ah Fogstar Drift gives you roughly 2kWh usable at 100% DoD (though I'd keep it above 20% to be safe), so you're looking at ~1.6kWh working headroom.

A well-insulated chest freezer should manage overnight fine — they're far more efficient than uprights. Just make sure your 400W array can recover the deficit the following morning, which in the UK means banking on actual harvest, not peak figures.

@Rodney this is something I've been looking into for my narrowboat setup, so watching this thread closely.

One thing nobody's mentioned yet — startup surge. Chest freezer compressors can pull 3-5x their running wattage on startup, sometimes for a second or two. Worth checking your inverter's surge rating can handle it before committing to a purchase.

Also, with a 200Ah LiFePO4 you're looking at roughly 2kWh usable (assuming 100% DoD on LiFePO4). If the freezer draws ~100Wh/day as @DownsCruiser suggests, overnight is very manageable — but I'd want to know your solar replenishment is reliable before running it year-round. Those winter days with a 400W array can be disappointing.

Has anyone tested a specific model they'd recommend? Something in the 40-60L range with a known-low draw?