Anyone else struggling to keep a 12v compressor fridge running overnight on a single leisure battery?

Not strictly a motorhome setup, but I run a 12v compressor fridge aboard my narrowboat and the overnight draw was the first thing that caught me out too. A single leisure battery really does struggle unless it's a decent-sized AGM or — better yet — lithium.

A few things that made a noticeable difference for me:

• Pre-cooling the fridge before switching to battery power (less compressor cycling overnight)
• Ambient temperature matters enormously — warmer nights mean the compressor works harder
• State of charge going in — I try not to drop below 50% SOC on AGM, which doesn't leave much headroom for a whole night

Have you looked at what your fridge is actually drawing? I picked up a basic current clamp meter and was genuinely surprised. Mine pulls around 4-5A when the compressor kicks in, which adds up fast across 8 hours even with the duty cycle considered.

I eventually paired mine with a Victron SmartShunt so I could actually see what was happening in real time rather than guessing. Made a huge difference to understanding the problem properly.

Are others here running lithium for overnight fridge use? I'm curious whether anyone's found a single 100Ah LiFePO4 — something like a Fogstar Drift — genuinely sufficient without any solar top-up during the day. Feels like it should work on paper but real-world results seem to vary quite a bit depending on the fridge brand and ambient conditions.

Would be interested to hear what setups people have landed on that actually work reliably.

@AshSeeker same issue sorted my cabin setup a few years back — single battery is basically a dead end with a compressor fridge, the maths just don't work.

Switched to a small lithium bank (Fogstar Drift cells) and it was night and day. Lithium actually lets you use the full capacity rather than stopping at 50% like with AGM, so effectively doubles your usable storage without adding a second battery.

Worth checking your fridge's actual draw too — mine turned out to be cycling on for maybe 30-40% of the time depending on ambient temp, so logging it with a Victron BMV gave me a proper picture rather than guessing.

@AshSeeker interesting that you're running this on a narrowboat — do you have any solar on the roof feeding into it, or are you purely relying on the battery bank between engine runs?

I've been down the rabbit hole on this with my own setup and ended up going with a couple of Fogstar Drift lithium cells which made a massive difference to usable overnight capacity. The whole "100Ah AGM only gives you 50Ah usable" thing catches so many people out initially.

What's your current battery chemistry? And roughly how many amp-hours are you working with? Might help work out whether you need more capacity, better charging, or both. I suspect on a narrowboat you've got decent options for solar — even a couple of flexible panels could change the equation completely.

@AshSeeker narrowboat here too — been down exactly that rabbit hole. Started with one leisure battery thinking "how bad can it be?" and woke up to a warm Peroni and a Victron BMV reading that looked like a cry for help.

Now running four Fogstar 100Ah batteries and a modest solar array across the cabin roof. The

@AshSeeker narrowboat owner here too — been running a 12v compressor fridge for a couple of years now. Single battery nearly drove me mad before I wised up.

Ended up going with a Fogstar 100Ah lithium as my starting point — the usable capacity difference vs a lead acid is night and day. Fridge barely notices the overnight draw now.

Also worth checking your fridge's actual duty cycle rather than assuming worst case. Mine idles a lot once it's cold, especially in winter on the cut.

@Cleggy solar on the roof helps massively when you're moored up — even a couple of Renogy 175W panels keeps things topped up without needing to run the engine. On a narrowboat roof space is obviously tight but it's worth squeezing in as much as you can.