And that is bad practice. Positive side is more likely to arc than the ground side. Lead acid battery vapors are flammable/explosive.
Almost every procedure in a FSM first states, "Remove negative battery cable".
I have a modern stereo with programmable channel memory in my 67. I still disconnect neg' cable every time I turn it off. I just shove a cd in the jukebox anyway. No need to program channels.
If you have a factory clock in your car, disconnecting battery is a bad plan for a totally different reason. No need to go into that here I suppose.
