“The incorrect battery may not stand up to the charge rate of a smart charge system and could easy overheat causing failure of the battery…”
“The battery charge light can illuminate for various reasons and the vehicle should always be checked for underlying faults before condemning the alternator.”
The timing of lunch and end of day play a part in congestion when nearing incorporations (keep an eye out for when you arrive in an area - you get there around lunch, expect lunch time traffic, you get there at quitting time expect congestion).
“So a volt meter simply measures the pressure or "voltage" present in the electrical system. The assumption is that if the voltage is between 13.8 and 14.2 (a 12 volt electrical system) that the battery is fully charged and the electrical system is working properly…”...
Interesting that you found it in the trunk. So intern b pulled 5 pieces and tossed one too many into the storage bin (trunk) for the assembly bot to use when called for? Kinda helps soothe the mystery feeling one gets when finding that spare christmas tree peg bouncing around the trunk.