The voltage measurements being conducted here are incompatible for assessing a battery's state of charge.
Utilising the battery voltage as an indicator of a battery's state of charge is valid only when the battery is at rest and there is minimal or negligible current flow. Recall the initial automobile alarms that were activated due to the detection of a battery voltage decrease produced by the illumination of the interior light.
The in-car battery voltage monitor consistently reflects the current draw, which might be beneficial for comparison analysis if one is aware of the appropriate healthy metrics. This method is ineffective for determining the state of charge of batteries according to standard published tables, as any substantial current draw will reduce the battery voltage, resulting in a fully charged battery not registering 12.6 volts or the appropriate fully charged voltage for its type. The appropriate method for utilising the published state of charge tables is to measure the voltage at the battery terminals while the vehicle is in a dormant state.
The recent failure of a recently installed battery, which ceased functioning in stop-start mode a few months post-installation, suggests an issue with either the battery or the charging mechanism and warrants investigation accordingly. An OEM battery is expected to endure beyond 2.5 years, leading me to consider that the battery may have been deficient from the outset, which is a possibility. What is the duration of the battery warranty?
I acknowledge that I am contentedly operating a vehicle with a battery that no longer facilitates the stop-start function, which ceased to function after 6.5 years of use.