Car stereo not remembering preset stations or clock time?

Question

I have recently purchased a brand new car stereo to replace my old one, it is all singing all dancing and my friend has the same one and has never had any trouble with it. Mine however, will remember the clock time, radio favourites and other similar things whilst the ignition is on but once the key is removed it will forget them all by the next time i turn it on, i think maybe the battery power is lost once the ignition is off and thus the unit is reset to its initial state but i just dont know how or why, any suggestions? thanks

Answer 1

I setup an in-house car audio powered by a PC source.

Works fine but... everytime I power off the head unit and the PSU, I lose all settings (radio presets, sound settings, etc)

Any clues ?

I understand there is no "constant" power coming (like in a car) , is there any head unit with a small lithium battery to retain settings ?