I just did a test run on an Iceco VL 74 single zone. I had to set it to 30 degrees in order to maintain an internal temperature of 35 - 39 with an average of 37 degrees. It was completely empty so will probably do a better job with food inside. I used a bluetooth Govee temp monitor, which I've been using for a couple of years and it's incredibly accurate. The cooler ran for 72 hours, set to the eco mode on my Ecoflow River 2 pro, which is a 768 wh power bank. The Iceco consistently maintained the temperature within a 4 degree band. I just got it and that was my first test so I'm not sure about it's long term reliability.