Anyone else finding 12V fridge compressors are the real battery killers on a build?

Just finished wiring up my Luton van after about six months of messing about, and I'm genuinely surprised how much the fridge is hammering my batteries compared to what I expected. Running a Alpicool C20 compressor fridge and even on a mild day it's cycling on pretty regularly. Rough figures from my Victron BMV-712 suggest it's pulling somewhere between 35-45Ah per 24 hours just sat in a cool-ish van, which feels high to me.

I've got 200Ah of lithium (two 100Ah Battle Born equivalents, cheaper Chinese cells from a well-known supplier) and 400W of solar on the roof. In summer that's absolutely fine, solar keeps up no bother. But last week we had three overcast days in a row and I was genuinely worried about hitting the low voltage cutoff. Ended up running the engine for 40 minutes each evening off the B2B charger just to top things up, which felt a bit defeatist.

Wondering if anyone's found practical ways to reduce compressor fridge draw — better insulation around the unit, pre-cooling before disconnecting from hookup, that sort of thing? Or am I just under-batteried for year-round UK use and need to add another 100Ah?

BreezySkipper | 847 posts

@LutonDream congrats on finishing the build! Yeah, the fridge is absolutely the sneaky one that catches people out. The startup surge is what really gets you – compressors can pull 3-4x their running current for that brief kick, which punishes batteries harder than the average draw figures suggest.

Worth checking if your Alpicool has an eco mode if you haven't already. Also, ambient temperature makes a massive difference – if it's sat near your engine bay or in direct sun, it's working overtime. I found positioning mine low down against the outer wall transformed my consumption noticeably.

What capacity batteries are you running? Lithium will handle the cycling far better than AGM if you're still on lead-acid – the voltage sag under compressor startup with AGM can be genuinely nasty long-term.

Linda1970 | 312 posts

@LutonDream congrats on getting it done! The fridge caught me out too when I first built mine. One thing worth checking is whether yours is sitting in direct sunlight or near a heat source – mine was drawing nearly double when the ambient temperature around it was high. Proper ventilation around the compressor made a noticeable difference to my battery drain. Also, what's your insulation like inside the fridge itself? Pre-cooling it before you leave home rather than letting it work hard from warm saves a surprising amount. I've got a 40Ah daily draw now which feels manageable. What size battery bank are you running? That might help figure out if it's genuinely excessive or just feels that way!