2008 Prius 12v Battery tests

This morning I ran a 12v battery test on my 08' Prius by pressing the display button and switching the headlights on and off 3x.

While on here I had only pressed the power button once (w/o brake) and i got a reading of 12.2V.

Next i turned on my headlights and it went down to 11.5V.

After i pressed the power button one more time w/ headlights on and it went to 11.2V.

Lastly i powered my Prius on w/ the headlights and got a reading of 13.8V.

My question is should I be getting a replacement 12V battery or is it still good? I am not really savvy at auto knowledge. I have been looking up this information but mosts videos/posts people have their battery dip below 11V in the ranges of 9-11.

Another question I have is since its above 12V when fully powered does that mean that it is working as it should and not be causing warning lights? My Prius currently has the BRAKE, ABS, AND VSC lights on since yesterday morning. I drove it around my home for about 2 miles and it seems to drive and sound like normal as well.

 

I also bought the car in 2013 and haven't bought a battery for it. Is there a way to figure out when a battery change was done? I also live in phoenix az where i know batteries don't live as long due to the weather