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

Running a small chest freezer off a 200Ah LiFePO4 and wondering if anyone's done the maths on this — or better yet, actually tried it.

My setup is a 24V 200Ah Fogstar Drift bank (so roughly 4.8kWh usable at 80% DoD). The freezer is a 68-litre chest type, rated at around 90W but obviously it cycles on and off rather than drawing constantly. I've seen figures suggesting maybe 0.5–1kWh per 24 hours for a small chest freezer, depending on ambient temperature and how full it is.

My concern is the overnight window specifically — say 10–12 hours disconnected from solar. Back-of-envelope suggests it should be fine, but I'm running a few other small loads too (a 12V fan, some LED lighting, maybe phone charging) so margins matter.

A couple of questions really:

1. Has anyone measured actual overnight draw on a similar-sized chest freezer? I know a cheap plug-in energy monitor would tell me, but I haven't got one to hand yet.
2. Does ambient temperature make a significant difference? The freezer will be in a stone outbuilding that gets properly cold in winter — does that actually reduce compressor cycling, or does it cause other problems?

I'm also wondering whether the Victron Cerbo I've got would let me set a low-voltage disconnect to protect the battery if I've misjudged things. Ideally I'd rather not wake up to a dead bank and defrosted food at the same time.

Any real-world experience would be massively helpful here.

LiFePO4_King | 847 posts

@MoorHamish Short answer — yes, very likely. A small chest freezer typically draws 80-150W when the compressor's running, but the duty cycle is usually only 20-40% overnight when it's not being opened. Real-world consumption tends to land around 0.3-0.5kWh per 24 hours for a well-insulated unit.

On your 24V 200Ah Fogstar (nice choice btw), you've got roughly 4.8kWh usable assuming 100% DoD, though I'd keep it above 20% for longevity, so call it ~3.8kWh practical. That's comfortably 7-8 nights of freezer runtime theoretically.

One thing worth checking — what's the starting surge current? Some compressors kick up briefly on startup. Shouldn't be an issue with a decent inverter but worth knowing.

What size freezer exactly and what inverter are you running?

Done exactly this on my narrowboat! 🙌

Running a small Cookology chest freezer off my 24V Victron setup. The compressor doesn't run constantly — mine cycles maybe 20-30 mins per hour once it's up to temp, so actual consumption overnight is way less than you'd think.

One thing worth knowing — ambient temp matters loads. Mine sips power in winter but works harder in summer when the boat interior warms up. Where are you keeping it?

Also definitely worth grabbing a Shelly plug or similar energy monitor for a week first to get your actual real-world numbers before relying on it fully. My freezer measured significantly lower than its rated wattage in practice.

With 4.8kWh usable you've got plenty of headroom honestly — @LiFePO4_King has the numbers right. Just watch your overnight DoD and you'll be fine.

BerlingoLife | 312 posts

Same here on the narrowboat — been doing this for two winters now. One thing worth factoring in that nobody's mentioned yet: ambient temperature matters a lot. In a cold engine room or below-deck space the compressor barely kicks in, so your overnight draw drops significantly. Mine sits in the engine bay and honestly barely touches the battery bank through the night from October onwards.

Also worth checking whether your freezer has a decent startup surge — some cheap units spike hard and can trip a smaller inverter. Run battery monitor logs if your Victron kit supports it, gives you real consumption data rather than guesswork.

@MoorHamish with 4.8kWh usable you've got plenty of headroom assuming you're not also running loads of other stuff simultaneously.

SD_Sparks | 1,203 posts

Worth adding to what @LiFePO4_King mentioned — ambient temperature makes a surprisingly big difference here. A chest freezer in an insulated van or boat in winter will cycle far less frequently than one sitting in a sunny outbuilding in July. I've seen the same unit vary by nearly 40% in consumption between seasons.

Also, with your 24V Fogstar Drift specifically, keep an eye on your minimum state of charge. I'd personally wouldn't want to dip below 20% regularly — so practically speaking you're working with closer to 3.8kWh usable rather than the full 4.8kWh. Still should be ample overnight, but worth factoring in if you've got other loads drawing simultaneously (lighting, phone charging etc.).

Do you know the model number of the freezer? That'd help nail down a proper estimate.

Ran this exact test last summer — 200Ah 24V bank (Fogstar, same as yours) with a small chest freezer in my outbuilding.

Overnight draw was about 1.2-1.5kWh depending on how warm the night was, so easily within your usable capacity. Main thing I'd flag that nobody's mentioned yet: how full the freezer is matters loads. Frozen mass acts like a thermal battery — half-empty freezer works the compressor way harder. I chucked some ice blocks in mine to fill the gaps and overnight draw dropped noticeably.

Also worth checking your inverter efficiency at low loads — some cheaper ones are terrible at partial load and you'll bleed watts for nothing. Victron Multiplus is decent for this but even then, pure sine matters with compressor motors.

Short answer: yes, you'll be fine with headroom to spare.