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

Running a small chest freezer off a 200Ah LiFePO4 battery is something I've been trying to work out myself actually, so keen to hear from anyone who's done it.

My setup is a 400W Renogy panel array feeding into a Victron SmartSolar MPPT, with a 200Ah Fogstar Drift as my main storage. I've been running 12V lighting and a small inverter for phone charging without issue, but the freezer is a different beast entirely.

From what I've read, a typical small chest freezer (something like a 60–100L unit) draws around 80–150W when the compressor kicks in, but obviously it cycles on and off rather than running continuously. Some people quote roughly 0.5–1 kWh per 24 hours in a reasonably cool ambient temperature, which on a 200Ah/12V battery (so ~2.4 kWh usable at 80% DoD) should theoretically be fine overnight.

But I've got a few concerns:

• Ambient temperature — sitting in a UK summer shed versus winter garage makes a massive difference apparently
• Inverter efficiency losses — I'm running a 12V system so I'd need to invert up to 230V for a mains-rated freezer, which eats into that usable capacity
• Compressor start-up surge — does anyone know if a standard modified sine wave inverter handles this okay, or do I need pure sine?

Is anyone actually running this kind of load overnight on a similar capacity bank? Would love real-world figures rather than spec sheet maths. Also wondering whether a 12V compressor-based unit (like a Brass Monkey or similar) would be a more sensible route

Depends entirely on how often your compressor kicks in — mine barely touches the Fogstar 200Ah overnight but that's because my static van is properly insulated and I'm not opening the freezer every five minutes like a confused labrador.

A full freezer is a more efficient freezer — thermal mass does the heavy lifting between compressor cycles. Your 400W Renogy array should comfortably recover it by midday though, assuming you're not in a Scottish winter where "sunny day" is basically a rumour. Worth chucking a basic energy monitor on it for a week before committing — I used a cheap plug-in one to clock my actual draw before I got smug about my setup.

@BrookRunner worth factoring in ambient temperature too — chest freezers work harder in summer, obviously, but also if you're in an uninsulated space. Mine's in a marshside outbuilding and I've seen consumption vary massively between seasons.

Rough numbers I've tracked: small chest freezer (around 60-80L) typically draws 30-60Wh per hour depending on compressor duty cycle. Over 8 hours that's potentially 240-480Wh. A 200Ah LiFePO4 at 12V gives you ~2400Wh usable (assuming 100% DoD which you wouldn't want), so realistically you're working with 1600-1800Wh comfortably.

Should be absolutely fine — but I'd run a cheap energy monitor on it for a few days first before committing. The Kill-A-Watt type meters are useful for baselining before you go off-grid properly.

Good points already made, but nobody's mentioned DoD limits yet. With LiFePO4 you can draw down to 80% DoD comfortably, so your usable capacity from a 200Ah pack is realistically 160Ah. At 12V that's 1,920Wh.

A typical small chest freezer (50–100L class) draws somewhere between 80–150W when the compressor runs, averaging maybe 30–50Wh per hour across a full cycle once you account for the off periods. So overnight — call it 10 hours — you're looking at 300–500Wh total consumption under normal UK ambient conditions.

That leaves your 200Ah Fogstar or similar with substantial headroom, provided your 400W Renogy array recovers it adequately next day. Where people go wrong is chaining several poor-efficiency days together until the battery's genuinely depleted.

Worth logging actual consumption with a Victron BMV-712 or similar before assuming you're fine — real numbers beat estimates every time.

Ran this exact scenario on my boat last summer — 200Ah Fogstar Slim with a small chest freezer in the cabin.

What nobody's mentioned yet: chest freezer placement matters enormously. Mine was wedged next to the engine bay initially and the compressor ran almost constantly. Moved it somewhere with decent airflow and overnight draw dropped noticeably.

@FormerMechanic68 is right about DoD, but also worth knowing that a well-loaded freezer (stuff packed in tightly) maintains temperature far more efficiently than a half-empty one. Frozen bottles of water as thermal mass are your friend.

My overnight draw was roughly 30-45Ah in mild weather, so 200Ah should be absolutely fine with sensible DoD margins — assuming your Renogy array recovers it by midday the next day, which 400W should manage comfortably barring a miserable grey British morning.