1995 Chevrolet S-10 CA Edition "replacement parts bright starts bounce" Questions

just replaced the alternator on my 2002 trailblazer, now the voltage needle bounces between 14 and 16. When I start the car the lights go bright to brighter. How is the battery? Might be a part of the

...bounce and vibrate. and bad wiring , can go open or shorted out bouncing all machines on earth can and do that. for sure hacks to wiring or collision damage not fully corrected, or road hazards rocks ...