jS5

Hi All,

Have a 2018 S5 Sportback. Live in Montreal where we have been having extremely cold weather. Been as low as -24C overnight this week. Have been curious with the charging system of my battery and decided to test is with one of those voltage readers plugged into cigarette lighter.
This morning at startup, the voltage reads 15.5V. It settled down to 15.2-15.4 depending on what accessories i had on. I also had it confirmed with an electrician with his gauge directly tested on battery. His reading was 15.4 with engine running/park and 12.5 with engine off.
Did a little research and found that 14.8v should be the maximum voltage with engine running. (BTW, with the same cigarette lighter guage, it showed 14.3 on my daughters Mazda CX-5 (Battery 3 years old).
First Question: Is it normal? Can the battery explode?
Second: Although the reading is 15.3v, is the battery capped for charging?
Third: Should I be worried and have the regulator checked by Audi? Will they just brush me off?

Would love to test it on another 2018 S5.

Feedback would be greatly appreciated.