Head unit losing memory after a few days

[D-Day]

I'm not sure if this is a charging problem with the alternator or battery, but for some reason my head unit is losing its memory/channel presets after a couple days. There is plenty of power to crank my truck up; it's a heavy duty battery with a heavy duty alternator, and my truck has gone far longer without running and haven't had this problem before. It's just started acting up in the past couple weeks.

Could the head unit be going bad? Is a wire messed up somewhere? It's an older Kenwood, something like a 3022 or 4022.