Getting 5V3A DC power source from Colt Z27AG
I was trying to plug a Jetson Nano (later upgraded to Jetson Orin Nano) into my old, unintelligent Mitsubishi Colt Ralliart Version.R (What a stupidly long name), to allow for some GPU-powered AI fun.
What I wanted to do with the mini computer is not of much concern here, though. This entry is about how to get a 5V 3A DC power output from the car. To power the Jetson, obviously.
Power requirements
Both Jetson Nano and Jetson Orin Nano are capable of taking a barrel jack 5V DC power input. The older Jetson Nano can also be powered by a micro-USB socket which is also 5V DC[1]. Less of a hassle for Orin Nano because it can only be powered by a barrel jack.
Either computer has a 'powerful' mode which consumes 15W. NVIDIA forum moderators or some actual employee decided to recommend a 5V4A power supply for that mode, having ~5W of redundancy in case of power peaks (or at least I guess so).
Also, it is very frustrating that NVIDIA for some bloody reason decided to change the dimensions of the barrel jack from Nano to Orin Nano as well. Jetson Nano uses a 5.5x2.1mm Center Positive barrel jack, and Jetson Orin Nano a 5.5x2.5mm Center Positive. It's absolutely not very difficult to find a converter but absolutely frustrating considering they are supposet to be of the same lineage.
Power from the car
Thoughts first
As many people have known, modern passenger cars usually run a 12V DC power for most, if not all, the electronics. However, at least for my Z27AG, it's 12V only when the car runs on battery. Once the engine is running the voltage rises to ~14.4V as the power is now supplied from the regulator and apparently it is rated at somewhere around 14V.
While I have faith in modern computers dealing with such tiny inconsistencies, the most important thing is still that the car is not directly having a 5V DC supply. So I'll have to use a buck converter or something similar to do a DC-DC step down. Hopefully, this converter also serves as a voltage stabiliser and keeps its output at 5V whether it is taking 12V or 14V.