Anyone know if a 200Ah lithium battery is enough to run a small chest freezer overnight?

Running a small chest freezer off a 200Ah lithium (a Fogstar Drift 12V, in my case) is something I've been wrestling with for my garden office setup. Wondered if anyone's actually done the maths on this or has real-world experience?

My chest freezer is a 60-litre Liebherr — pulls around 100W when the compressor kicks in, but obviously it's cycling on and off rather than running flat out. I've seen people quote a rough average of 0.5–1 kWh per 24 hours for a well-insulated chest freezer, which sounds manageable.

At 12V, a 200Ah bank gives you around 2.4 kWh usable (assuming you don't want to dip below 20% SOC). So in theory, overnight — say 10 hours — it should be fine, especially if the freezer is already cold from daytime solar charging periods.

But here's where I get uncertain:

• Does ambient temperature massively change the compressor duty cycle overnight?
• Would a Victron SmartShunt give me accurate enough real-time consumption data to feel confident, or do I need to overspec the battery bank?
• Is 200Ah cutting it too close, or is there a comfortable headroom there?

The plan is to eventually tie this into a small solar array — probably two 200W Renogy panels on the garden office roof — but for the moment I'm thinking about whether the single 200Ah battery can hold the fort overnight without solar topping it up.

Anyone actually running a chest freezer off a similar-sized lithium bank? Would love to hear whether you sleep soundly or spend half the night checking the BMS app! 😄

@ExFarmer90 done exactly this in my motorhome. A decent small chest freezer — say a 60-80L — pulls around 30-45Ah per 24 hours once it's up to temperature, so overnight you're looking at roughly 15-20Ah. Your Fogstar Drift should laugh at that.

The gotcha nobody mentions: startup surge. First time mine kicked the inverter into protection mode because I had the low-voltage cutoff set too tight. Sort that first.

Also factor in ambient temperature — a freezer in a cold garden office in January barely runs at all, but a hot summer shed will punish your battery harder. My setup in Scotland means winter's almost free running.

200Ah is genuinely comfortable for this use case. You could run two freezers and still sleep soundly.

@ExFarmer90 did this exact thing for my static caravan last summer. Short answer: yes, just about.

A Fogstar Drift at 200Ah gives you around 180Ah usable (90% DoD). Overnight — call it 14 hours — your freezer should only nick maybe 25-30Ah if it's

Really useful thread this — I've been eyeing up exactly the same setup for my static caravan!

Quick question though: does the ambient temperature of where you're storing the freezer make a big difference to those consumption figures? Mine would be sitting in an uninsulated outbuilding, so I'm wondering if it'd work harder in summer and actually less in winter (or does it struggle when it gets really cold)?

Also @RetiredElectrician — you mentioned the Fogstar Drift specifically. Did you find the battery's low-temp cutoff ever kicked in during winter nights? That's something I haven't seen many people talk about with the Drift range and it's nagging at me before I commit to buying one.

Feels like 200Ah is cutting it fine with no solar input overnight — would a second battery in parallel be the sensible belt-and-braces approach?

@ExFarmer90 one thing nobody's mentioned yet — the ambient temperature of where you're siting the freezer matters enormously. A freezer working harder in a warm garden office will chew through significantly more Ah than the figures @MountainHermit quoted, which I'd assume are from a reasonably cool motorhome environment.

Also worth noting: Fogstar quote 200Ah but you should only be drawing down to 20% SOC really, so your usable capacity is closer to 160Ah. Factor in inverter inefficiency if you're running AC (not DC compressor), and that figure shrinks further.

For my shepherds hut setup I run a Victron SmartShunt precisely so I can monitor actual consumption rather than guessing. I'd strongly recommend doing the same before committing — a week of logged data tells you far more than any rule of thumb.

@NaeClue13 raises a critical point but there's another layer to this — compressor duty cycle is what actually kills your capacity budget overnight.

My setup runs a 12V compressor fridge through a Victron SmartShunt, and the logged data consistently shows duty cycle swinging between 20–40% depending on ambient and how often the lid's opened. A chest freezer at stable ambient with no access overnight could drop to 15–18% duty cycle, which dramatically changes the maths in your favour.

Rough figures for a typical 100W rated compressor chest freezer:

• 100W × 20% duty cycle = 20Wh/hr average
• Over 10 hours = 200Wh
• 200Ah × 12V × 80% usable = 1,920Wh available

You're using barely 10% of your Fogstar's usable capacity. The battery isn't your limiting factor — your inverter efficiency and overnight voltage sag are worth monitoring more closely.