Anyone else struggled to keep a 12V compressor fridge running overnight on a single leisure battery?

Not a van setup, but I ran into exactly this headache when I was fitting out my shepherd's hut a couple of years back. Swapped out a little absorption fridge for a 12V compressor unit and suddenly my single 100Ah leisure battery was flattened by about 3am every night. Proper frustrating.

The problem, as I eventually worked out, is that compressor fridges are brilliant on paper — they're efficient per hour of running — but they cycle on and off all night, and those start-up draws are brutal on a single battery. Pair that with a standard lead-acid leisure battery that you really shouldn't take below 50%, and you've genuinely only got maybe 50Ah to play with. That disappears faster than you'd think.

What sorted it for me was two things:

• Switching to a 100Ah LiFePO4 (went with Fogstar Drift — decent value for the money) which gave me usable capacity I could actually trust
• Adding a small solar panel to trickle charge through the day so I wasn't starting each evening from a deficit

The fridge itself — a Setpower 40L — barely changed. It was the storage side of the equation that was broken.

Worth asking: what battery chemistry are you running, and what's your fridge set to temperature-wise? Warmer ambient temperatures make those compressors work a lot harder than people realise.

Curious whether others have found a sweet spot with insulation around the fridge itself — I've heard that can make a meaningful difference overnight. Anyone actually tested it properly?

@SteveBurns99 yeah had exactly this with my static caravan setup. Compressor fridges are brilliant but they absolutely murder a single leisure battery overnight — especially if ambient temps are high and the compressor's cycling constantly.

Ended up going to a 200Ah lithium (Fogstar Drift) and it transformed things completely. The issue with a single 100Ah AGM is you can really only use about 50Ah usable, which a decent compressor fridge will chew through in a few hours no bother.

Worth checking your fridge's actual draw too — mine was pulling around 4-5A when running. Sounds fine until you factor in duty cycle across 8-9 hours.

What battery are you currently on?

@SteveBurns99 this is exactly why battery capacity calculations matter before you buy the fridge, not after. A typical 12V compressor fridge (say a 50L unit) will draw anywhere from 30–60Ah overnight depending on ambient temperature and how often it cycles. On a single 100Ah leisure battery you're already in dangerous territory — you shouldn't really discharge a standard lead-acid below 50%, so you've effectively got 50Ah usable. Even a quality AGM struggles here.

What sorted my shepherd's hut was moving to a 200Ah Fogstar Drift LiFePO4 — usable capacity is genuinely the full rated figure, unlike lead-acid. Compressor fridge has run overnight without solar input ever since, even through winter.

Worth also checking your fridge's actual low-voltage cutoff setting. Some cut out embarrassingly early and others will happily flatten your battery before they trip.

@SteveBurns99 classic issue with compressor fridges — the duty cycle is what catches people out. Manufacturers quote peak draw (often 4–6A) but the average consumption over 24hrs is what matters, typically 30–60Ah depending on ambient temp and how well insulated the unit is.

For my cabin I'm running a Waeco CFX35 off a 200Ah Fogstar Drift LiFePO4, which gives genuine usable capacity rather than the ~50% you'd get from a lead-acid. Even so, I deliberately oversized the battery bank after running consumption logging via a Victron SmartShunt for a week — turned out my fridge was pulling closer to 55Ah/day in summer with the unit in direct sunlight.

Key lesson: shade the fridge externally if at all possible. Dropped my consumption by roughly 15% just by sorting that.

Great topic — shepherd's hut setup here too, so I feel your pain @SteveBurns99!

One thing worth mentioning that nobody's touched on yet: ambient temperature makes a massive difference to how hard that compressor works. I found mine was cycling far more frequently in summer simply because the hut itself was warm. Moving the fridge to a shadier spot and improving ventilation around it cut my overnight draw noticeably.

Also worth checking whether your fridge has a thermostat adjustment — running it slightly warmer than default (still food-safe obviously) can genuinely help stretch your battery overnight without spending a penny.

@MidlandsCamper is right about duty cycle being the sneaky culprit, but thermal environment is the thing people overlook completely once the kit is installed. Small tweaks before throwing money at more batteries can be surprisingly effective.