I connected the Nano to a 12V car battery through an automotive-grade 12V to 5V DC-DC converter. The car battery was very old and was producing only ~8V. The car ignition took a couple of seconds extra to turn on the car.
I tested the device in 2 ways.
After the car was on, I will connect the 5V to the barrel jack and it would power up the nano. I had a raspi v2 camera recording at full resolution, a TF object detection model running and an external hard disk connected for storing the data. It worked properly. I took the car for an hours drive, I switched off the car and started it again in a few minutes. The nano kept going without any power disconnection.
The next day morning, I started the car with the nano connected. The DC-DC converter failed and the board failed too. The board wouldn’t boot again with any other power supply.
My question is how the battery that had only 8V in it killed my board. What will happen if I connect the nano to a 4v(or even less) power supply? Will it harm the board?
Also, I read about brownouts happening at insufficient voltages, how to identify brownouts happening? Are there any logs that are saved about the power shortages other than tegrastats?