Originally Posted by insane79
I went to the dealer with my car key & he checked it on the key reader & toke a print out & said the car battery voltage is 13.8v, even i was surprised hwo he can check it without checking the battery in front of him
The key reader stores a bunch of diagnostic info, including the battery voltage as of last removal. I forget why, but there you go
For that matter, the car can check its own voltage, which you can read with an INPA cable. You can open the trunk and measure it with a multimeter, but then, hey, why bother.