I've had a few that say 12.4 all day long till you hit the starter the then drop like a rock. Strangely enough some walk right back up to 12.4 First time I experienced it I chased my tail for 2 days until I happened to be watching the DVM when I hit the remote start switch. In over 50 years I had never seen this happen. But have seen it several times since and read about it as well