The Wifes' 2015 4Runner Trail got a new battery last week. After I charged/installed it, I put a volt meter across the terminals, with the engine running, and got ~13.4v. She had just pulled in, and probably had the A/C on, lights off. Is that reading in range?

 

I don't think so. If the AC was ON then it should have been idled up. 13.4v on a running system is just above resting battery voltage and could mean your regulator or alternator is not charging correctly. You should have about 14.5-15.0v. Have the system tested at a local parts store. You don't want the wife on the side of the road. You'll never hear the end of it.

 

Thanks for the input. I just re-checked it, and got 14.12v. I will follow your advice and have the system checked ASAP. I'm not so concerened with her yapping, as with her safety.

 

Just checked the battery with key off, about 5 min after I started it for the previous check. It read 12.86v, and the vehicle has been used for short (6 mile) trips, daily, for the week or so since the new battery was installed. Should be GTG (this 4runner only has ~50K on it), but will make time for a quick system diag check, just to be sure.