0.8 Volt variation in charging Voltage is nothing when you are dealing with 150-200 Amp output on an alternator and the heavy electrical demand on modern vehicles.

As long as the Voltage does not drop below 13.5 Volts or go above say 15.0 Volts on a regular basis, I would not be too worried. But like anything you will need to get a feel for your specific vehicle. If you are using the Hidden OBC Menu, note that often I had a 0.2-0.3 Volt correction factor to the display due to internal Voltage drop in the vehicle, often the Voltage a the battery is slightly higher than what is displayed on the OBC.

Most modern vehicles tend to operate in the 13.5-14.5 Volt range. I give a slight bit of variation on the upper end of the Voltage range, just because I do sometimes see some occasional upper range spikes when electrical demand is removed and the regulator is slightly slow to respond.

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2008 4.8i Black with Tabacco. Black Y-spoke wheels and shadowline trim.