I think a lot of portable fridge failures are caused by a weak intermittent connection where the ciggy plug nipple meets the back of the receptacle, This spring loaded nipple (+) is always pushing and trying to work the rest of the plug back out of the receptacle. Add a bunch of vehicle vibrations and there is at some point, where it barely makes contact and can be turning on and off dozens of times per second which i think is tremendousy stressful on some electrical componets within the compressor controller
There are many better ciggy plug designs, like the one from Blueseas, and its matching plug which can kind of lock together, I own one pair and am not all that impresed with the locking. Also, using this connector driving some LED lights through a PWM LED dimmer, when dimmed, the plug receptacle was emitting a high pitched humming from within the connection. This hum could be made to change tempo or eliminated simply by forcing the plug deeper into the receptacle, but the second I let off the high putched whining would begin again, and this is from a 12v ciggy plug/receptacle designed from scratch to eliminate most of the inherent weaknesses in the spring loaded worldwide ubiquitous design, and it is still an unreliable highly resistive connection prone to failure..
All these portable fridges have to have some sort of access panel to get to the fridge compressor and compressor controller. Inside of this there is likely a spade connector with a matching 1/4" quick connect insulated wire termination representing + and - 12-24vdc input.
There are these Piggy back connectors:
These should allow one to easily run their own 10 or 12awg wiring ( fused at battery) right to the fridge's compressor controller, completely bypassing the ciggy plug receptacle and the fridges own 2 pin connector on the fridge body. The fridge will get a higher battery voltage, with much higher reliability, and the battery protection settings will be more accurate and not shut the fridge down and spoil food when the battery is not in any danger of being overdepleted.
If one takes care with the access panel screws, and needs to warranty the unit, they can then remove their piggyback spade connectors, return it to stock, button it up, and they can't say the warranty is void because you cut the cord of the ciggy plug.
45 to 27 watts consumption is about right, but the question is how many minutes per hour does it run?
In 75 f ambient, keeping 32.5f internal temps, mine runs about 4.5 minutes on, 12 to 15 minutes off. it depends on door openings and the amount of food already cooled to temperature X, within.
Inside the access panel, there will be the compressor, compressor controller and the condenser, the finned part which gets hot. The condenser will likely have a fan on it. This fan is likely a sleeve bearing Piece of donkey doo doo.
HUge gains in efficiency can be obtained with a higher quality fan designed to evacuate the heat from the condenser to the atmosphere. Extra insulation of the fridge body, but that which allows maximum heat extraction from the condenser is the way to make fridges more efficient and reliable, and can take a significant load off the battery powering them.
These fans can easily get loaded with lint and dust, which will also limit the ability of the unit to extract heat from food items and expel that heat to atmosphere. So one might want to familiarize themselves with just how to access the fan in order to clean it.
My fridge is always on, and I employ an air filter on the intake. The upgraded 120mm Noctua A12x15 fan attached to the 120mm condenser( which looks like a mini car radiator) pushes air through the condenser, across the compressor and compressor controller, then into the next cabinet compartment, which can either be outside the van or inside the van, or both. Essentially I am pulling the coldest possible interior air source across the condenser once, and push it out of the compartment all with one fan that comes on with the fridge compressor. Every 4 to 5 weeks the white filters I taped into place on the intake are brown to black and loaded with dog hair, human hair, clothes lint and other dust like particles. I can vaccuum them mostly white a few times before I replace them. Even with this filtration, a very fine film of dust builds up on the fan blades and leading edges of the condenser fins, that I clean once every 1.5 to 2 years.
You can just plug it in and go, but you can also add a lot of spit and polish to get more out of the design to improve efficiency and reliability, if one is so inclined.
The internal fan can also be a source of noise that might be louder than the compressor itself. Generally the fans make more noise when the restriction( condenser) is directly on the backsides of the fan blades. A fan like the Noctua NF-f12 or the A12x15 are designed to push air through a restriction. When I modified my fridge's fan to push instead of pull, and used the Noctuas, the fan noise went to inaudible and the time the fridge ran each cycle on was reduced by about 30 to 40 seconds. The Noctua NF-f12 only draws 0.05 amps, compared to the fan my fridge came with which draws 0.13 amps. Noctua fans come with a 6 year warranty and once they get the proof of purchase a new fan arrives from Austria in less than 5 days. They also might send a prepaid UPS label to get the failed fan back to inspect.
It is good to see prices dropping to the 300$ level on portable 12vdc compressor units. The offerings in the last 15 years have mostly been in the 500 to 800$ range, like those from Norcold, Dometic, Vitrifrigo, Engel, ARB, National Luna ,Truckfridge, Indel-B, and a few others.
I hope they did not have to cut too many corners to meet this price range.
Having owned Norcold, i am very much Biased towards fridges emploing the Danfoss/Secop bd35f compressor.
The Norcolds sawafuji compressor was very loud and would induce harmonics from the vibrating swing compressor. How well this swing compresor's vibrations are dampened play a huge part in the total noise made.
But I found the Danfoss to not only be 1/3 the noise, but also more efficient, as it has the 120MM condenser and 120MM fan. The Norcold lasted 5 years, the Vitrifrigo is on its 7th.