Long story short, this morning wife got a CEL and a bunch of warnings. During an abortive attempt to go to the dealer (that's another story in itself) and my getting a chance to listen to what the vehicle was doing I decided to test the battery on my carbon-pile tester, and as I increased the load the voltage dropped from over 12V to 6V, and when removing the load the voltage did not recover as far as it had measured when we started. By the time we had gotten home prior to my load-testing the battery, all of the warnings and the CEL had shut off. I suspect that first-thing when my wife only drove a mile at low-speed on surface streets, the weak battery from sitting overnight was significant enough that it caused miscellaneous electrical gremlins. Once we'd driven the freeway speeds to reach the dealer the alternator had recovered the battery enough to continue diminshing the issues. Bought the new battery at Costco. The existing battery was an H5, I was able to remove the insulator/protector jacket after I'd pulled the cables and strap but with the battery in-place and without using the velcro. Costco insisted that the car should have an H6, so that's what we bought. I did have to un-velcro the insulator/protector to put it on the new one, and it was a bit of a chore to get it down in there with the positive battery cable, but it did fit. So the H5 was installed at the dealer under warranty around two years ago. Because it was a warranty swap they wouldn't honor a battery warranty even though the battery had 36 months stamped on it. I've seen conflicting reports on what battery it is supposed to have, some have said H5, but clearly if the H6 and the jacket fits, not sure why the H5 was installed. Lastly, I did have some built-up corrosion on the harness connectors, wirebrushed that back to clean them. Both had it. It wasn't the cause of the voltage drop (I tested the battery with nothing but the tester connected) but obviously not good to have that kind of buildup.
