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

Got a bit of an experiment on my hands and wondering if anyone's done the math on this already.

Running a small chest freezer (about 60-70W rated, Aldi special) off my van setup. Currently got a single 200Ah Fogstar Drift LiFePO4 and a Victron 230W panel keeping it topped up during the day.

Question is whether that battery alone would realistically carry the freezer through a full night — say 10-12 hours — without the solar contribution.

I know chest freezers cycle on and off rather than running flat out, so I'm guessing real-world draw is maybe 30-40% duty cycle? That would put overnight consumption somewhere around 200-300Wh maybe? Seems manageable but I don't want to hammer the battery below 20% if I can help it.

Few extra bits of context:

• Ambient temps in the van drop to maybe 8-12°C overnight (currently parked up in Luton, nothing exotic)
• Freezer is set to around -15°C
• I'm trying to avoid running it all the time on my leisure setup as I want headroom for EV charging off the system during the day

Has anyone actually monitored their freezer draw with a Shelly or similar energy monitor? Would love some real figures before I commit to running it overnight and waking up to a flat battery and defrosted sausages.

@LutonNomad depends heavily on the duty cycle. A 60-70W rated freezer doesn't run continuously — compressor cycles on and off. Typically you're looking at maybe 30-40% duty cycle once the chest is cold, so realistically 20-25W average draw.

Over 8 hours that's roughly 160-200Wh. On a 200Ah lithium (assume 12V) you've got ~2400Wh usable (most lithium is 80-100% DoD). So yeah, comfortably overnight.

Caveat: ambient temp matters a lot. Warmer = compressor runs longer. Also, "Aldi special" — check it's not a frost-free model. Those run significantly harder.

My garden office setup runs a small fridge off a 100Ah Fogstar and it's fine through the night, and that's only half your capacity.

@GlenDoug is right on the duty cycle, but also worth noting your Victron BMV will show you exactly what it's actually pulling in real-world conditions — mine scared me the first time I looked at it properly 😅

@LutonNomad ran almost exactly this setup last winter as emergency backup for my garden office freezer — small chest unit, similar wattage.

Real-world draw was closer to 25-35Ah over 8 hours once you account for cycling. Ambient temperature matters a lot though; cold nights actually help the compressor work less.

On a 200Ah lithium (usable ~180Ah if you're not hammering it to zero) you've got plenty of headroom overnight. You'd struggle to flatten it on a freezer alone.

The thing that'll catch you out is the startup surge — make sure your inverter isn't undersized. Had a cheap unit trip repeatedly before I swapped it for a proper Victron unit that handles the inrush without flinching.

One night's experiment with a clamp meter on the cable will tell you more than any calculation anyway.

@LutonNomad worth adding — ambient temp makes a massive difference with chest freezers. Mine pulls way more in summer than winter, so "overnight" varies a lot depending on when you're testing.

Also, a 200Ah lithium (Fogstar Drift or similar) gives you roughly 160–180Ah usable in practice. If your freezer averages ~25-30Ah overnight (realistic duty cycle as @GlenDoug mentioned), you're absolutely fine with headroom to spare.

One thing I'd watch — freezer startup surge can sometimes confuse smaller inverters. Worth checking your inverter's surge rating isn't getting hammered on compressor kick-on.