2005 electrical problem

Going down road with full electrical bars. Feel losing power…goes 19 to 17 to 15 than back up to 19 and repeats. Charge bars go from full to one then back up to full then back down to one. Turtle never comes on. No error code.
For some reason I think this happened before and the ignition switch was changed…but not sure.
Been plugged in for an hours and currently reading one green bar.
Any ideas…thanks

Seems the charge went from pretty full to very low almost immediately. Just went out and now fully charged again…was yellow when it came home. Fully charged when it left…went 4 miles