I found this video interesting. He takes the time to explain the communication between the PCM and the Alternator and why there can be a fault in the system even though the battery light is off and the gauge shows it's charging.

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'15 Dodge Journey - 90,000 KM's - SSO 5w20
'06 Hyundai Santa Fe - 535,000km - SSO 0w30 (R.I.P)