So two weeks ago I noticed on my Chrysler 200 a bad noise (like gurgling popping noise) coming from car and my battery light coming on. Turns out I needed a new alternator the regulator inside was catching gear causing the noise. Once it was replaced the noise was gone and for a little the battery light was off. Then the light turned back on. Tested new alternator with removing positive cable off battery and it immediately turned off. So we replaced the alternator and battery. All was well until 20 minutes into driving the battery light came on again. I have noticed it does not turn on until 20 minutes into driving it. My friend who works at a Chevy dealership came to check it out and he tested the alternator, despite being new it would test at 12.5v and then shoot back up to 14v. Battery tested good with car running on and off. Being as it was a Chrysler and not a GM or Chevy, and that for the most part everything tested good, he suspected it may be the ECM. Other than the battery light my car honestly runs fine. Can anyone give me insight what this may be before I get raped at a dealership? No check engine light, just a battery light.