I ran my Ironman (40 litre) fridge on –20 C for 3 days on my main battery only driving 30min each day.
Its a Braille B7548, 945CCA & 75AH with a 5 year warranty at $400 its not cheap but is cheaper then a second battery set up (including a second battery).
I have had this battery for less then 6 months and an impressed with its performance thus far.
To be on the safe side I also carry a 900amp jump pack but have not had to use it since I got the battery (touch wood).
I do plan to fit a second Braille in an Ark power pack when I have the $$
The Ironman fridge works great and fits 1.25 bottles standing up.
One issue it has is that the lid isn't removable, it can be a pain if you don't have the overhead room to open the lid fully
+ 2 on Battery Business