About a day, most "assisted" cool boxes use about 4-5 amps, look at the amp hour rating of your battery and simply divide. A gas one might be a better bet @Merlin Cat, but as you know will likely cost much more than the £60 for an assisted coolbox.
Could you not just check into a nice hotel with a jacuzzi? Much better. And you wouldn't have to dangle an extension through the window
We only use it ,240v when on hook up or 12v when driving, we always have hook up when we camp (wife insists!) I’ve got a 3 way fridge again normally used on hook up , only time I’ve used it on Gas is at techenders , don’t leave it on overnight though. Left the 12v plugged into the wife’s car once , drained the battery in a day ! Sent from my iPhone using Tapatalk
We bought a “Sirbir” 3 way coolbox/fridge 16yrs ago from CCC/Go Outdoors and it cost £185....... it’s been used every time we go camping and for the last 8yrs it has been used in the house as well (continuously on 240V) as my beer fridge. IMHO it’s one of the best things we have bought. There’s one on eBay at the moment https://www.ebay.co.uk/itm/SIBIR-RC...671914?hash=item2ce989a0aa:g:i38AAOSwJcxcvxh1 A friend has given me a similar sized one that is made of plastic so lighter. I have replaced the 2 elements as one was 24V DC and the other 110V AC so it’s now 12V and 240V. I’ve just got to change the gas jet so it will run on camping gas and not Propane........ I decided I wanted to have a beer fridge for me instead of sharing the space with the kids soft drinks and milk.....I’m selfish like that......so, when camping for longer periods we will have 3 fridges on the go and I will be sat on my Sirbir so no one can pinch my stash of lager.
My leisure electrics only power the coolbox nothing else at the moment, think from memory I've a 65AH leisure battery connected to a 100w solar panel, and Durite VSR from the starter battery. This works fine for a number of days, although cant say we didn't drive around at all. I bought a really expensive Waeco CFX35 which has really low power consumption, I would have liked to install a proper fridge of similar ilk but this gives me great flexibility and with one power supply make life simple. When it comes to how long will your leisure battery last then its likely to be down to how much you spent on the cool box. if you aren't moving anywhere you could always put a spare 'leisure' battery in?
Old Euroengel compressor fridge/ freezer coolbox. Same guts as a compressor fridge under the mesh at the end. Average drain 1 amp. Will go down to -18 degrees C so its a 3 star freezer too.. Around £600 new. Paid £40 at a boat jumble. Indefinite run time with solar including dull days.
If you want 4 days it’s got to be gas or a Compressor type Brother in law uses one of these Dometic CoolFreeze CDF 26, 21 Litre Portable Compressor Fridge Freezer, 12 V/24 V https://www.amazon.co.uk/dp/B00SATJLZI/ref=cm_sw_r_cp_api_i_FIeYCb41ZGV5T A bit of reading about the different types http://thelatebay.com/index.php?threads/fridge-types.11369/
i like the setup that @PIE has in his split, compressor fridge kit fitted inside vintage aluminium cooler. Very nice: http://thelatebay.com/index.php?threads/57-split-finished.49280/page-9
i actually thought about doing this to sell them but it would depend a bit on each van and its location in the van
the kit used in that toolbox conversion is £399.95 plus £85 for the mains converter so its not a cheap option.
Not to a Subaru, I just want a cool box. Would it need to be bolted down (I read pie’s thread) as I’d like it not to be? I guess the other option could be to sell the cooler and buy one of the compressor ones...
if its a small one then yes just sell it and put the money towards a compressor coolbox. if you get a compressor coolbox then it means it is still moveable rather than a permanently installed fridge