I applaud your inquisitivness.
The fan is an 80mm fan, the open end shown is the suction side. Can you see where this fan's wires run? Can you access them, or follow them to where they enter the compressor controller? It looks like there is a pretty good gap inbetween condenser and the casing/cover? More than 25mm/ one inch?
The compressor is a cute little thing. It does look like the air circulation over it is limited by the wiring bundle. The fan will be pushing some preheated air from condenser at it. the compressor generates heat too so it is better that the fan blows
That condenser is not really all that efficient, with not much surface area, and part of it well away from the fan's flow, but these fans tend to have 4 hotspots which exit fan at wider angles when unrestricted. not sure in that configuration.
what are the dimensions on the venting grates. Could a 120MM( 4.75" fan be attached to the inside of them? how about a 92mm(~4 inches)?
I think I would either try adding a fan to blow cool air directly into the existing fan, or if easier, locate it to exhaust on the other side of the compartement. Fans tend to do better with restrictions in front of rather than behind the blades.
It appears as if that existing 80mm fan would be very hard to remove and replace, so i would Aim to supplement the airflow either by forcing more air into the condenser, or haviing an Exhaust fan sucking the heat out and forcing it out the regular exit.
The Noctua NF-f12 at only 0.05 amps is likely a lesser amperage draw than the 80mm fan they used and will likely not overload the circuit intended to power the fan, if added to it.
If I owned that fridge, i would likely attach the NF-f12 to the casing interior , oriented to blow into the existing fan, and likely open up some of the grating. I am usually not worried about warranty voiding though. Once I establish it works properly I will modify.
You could also perhaps add some refelctix in between cooling unit and the fridge box itself to reflect the heat generated there from entering the cold portion of the box.
The coler you can keep that cooling unit interior, the longer the compressor and compressor controller will last. The earlier danfoss bd35f' s failures were from teh compressor controllers overheating when there was a huge heat load placed in the fridge in hot ambient temps. They soon added a finned heatsink on the back of the compressor controller.
Splicing the wiring that leads to the existing fan is pretty simple. The controller should easily handle the 0.05 amps extra of the NF-f12 fan, and this fan should be able to pump ~53 cubic feet od air per minute through the cooling unit. the existing fan likely recirculates 50% or more of the air it moves, whereas a fan on the casing should exchange nearly all the air it moves, which will lead to improved cooling nad extended cooling unit lifespan, and allow for shorter compressor run times, reducing overall battery consumption and allowing it to run for longer in hot ambient temps.
Thanks for the effort of the providing the pics. You have done everybody who reads this thread well to have done so.
The fan wires are usually red and black and about 22 gauge. One of them is likely sharing the ground with the main ground from the input plug, the other wire might have a dedicated output just for it.
Not sure of the sizes but some piggyback connectors can make attachng an additional fan easy without any wire splicing.
https://www.amazon.com/0-250-Female...63&keywords=crimp+connectors+quick+disconnect
if worried about warranty one can make it appear as if no modificatons were ever added. I'd use amazing goop to glue a NF-f12 fan to the side opposite the existing fan and use the piggy back connectors.
Since you have it open, and perhaps do not require the 'portable' moniker anymore, consider bypassing the powercord connector and running 10 gauge wire right to compressor controller. The move voltage one can deliver to the compressor controller, the better it will run and be slightly more efficient too.