hi, it’s not about the car, but I want to use the audio components. I want to build a portable music box. I want to use the end stage and feed it with a mp3 player. however, the question remains about the power supply. for this I wanted to use 2 smaller batteries in parallel to supply the end stage with electricity, but unfortunately I have heard that it should not be so good for the batteries to simply switch them in parallel. what happens in the end charging and in the open air adecycle with 2 parallel batteries? what if they are the same? what if 2 different? main reason for using 2 batteries is first the price and second the better weight distribution.