I had the same problem identifying which wires were just + and -, and E mailed Noctua. They linked a page showing where they list what is what, but now I cannot find it.
But not wanting to pull out my fridge to check, I found it elsewhere online and yellow is + and black is -
In October mine will have been mounted on my compressor fridge's condenser for 5 years, and my fridge rarely has seen voltages less than 12.1v and daily sees mid 14's. I am not sure what voltage the compresor controller allows to the fan though, the fridge can run on 12 or 24v but they say to use a 12v fan so the fan voltage is likely regulated to 12.0v and does not vary with battery voltage.
I have other Noctua fans, 60mm and 80mm, which have spent many hours up in the high 14's and occassionally higher when EQing a flooded battery, and even more time at 13.6v. I'd not stress the charging voltages, and at just 0.05 amps, I'd not really bother with a thermostat for it. but a snap switch would be what I would choose if I did.
https://www.amazon.com/Emerson-3F05-1-Adjustable-Snap-Control/dp/B000PY7T7I/ref=sr_1_3?ie=UTF8&qid=1...The Noctua NF-f12 fan comes with two low noise adapter cables. If you want to keep the sleeved connector on the fan's lead, then I would sacrifice one LNA cable and cut and splice the wires on it, not including the resistor mid LNA cable.
The LNA's have a simple resistor on the power cable to reduce the voltage and slow the rpm's. I use them on a loud 'Addo' fan I pulled from a failed Wfco that pulls much more current ~ .22 amps at 12.6v, and while the resistor gets hot, not dangerously so. That fan exhausts my electrical cabinet and can also help vent my fridge if I choose to retain condenser heat inside( compressor fridge, no byproducts of combustion), otherwise I expel it outside vehicle instead.