12V battery died with ambiguous messages

Yesterday morning I tried to start my MY13 Volt with 57K miles. The boot-up took longer and then gave a weird message about 'service power steering'. The wheel was very hard to turn indeed. It also did not want to charge. Since I was under time pressure to get to work I gave up and I took the backup car. It seems I a pretty serious issue. I had visions of having to finally having to bring in the Volt for service (I have never done that in 4+ years) and worried how to get the car there.

When I got home after work I tried again. Now there were even more failure messages. Suddenly I noticed also the red battery symbol next to the many other error lights. So I checked the 12V battery voltage in the trunk: Bingo.. It was down to 10.1V. I charged the battery a little and then the car started normally.

I went to a local auto-part store and bought a new battery. Installing that in the back trunk is a little harder than putting it under the hood. But it is easily doable with the right wrench set. The good news was that ALL my settings survived the power outage. My Toyotas always reset to factory default, including the radio presets.

It is a bit odd that the Volt does not give me the 'root problem' of low 12V battery Voltage. Instead it gave loads of other data about modules that fail because of low voltage. It is also strange that the on board charger does not charge the 12V battery from the 360V main battery in this case. It only took a little push from the external battery charging to jack the voltage up enough to start normally. So in all, I think that a little software could have given a warning in time for 'service 12V battery soon', instead of potentially stranding people in the middle of nowhere. The state of charge is visible on the OBD bus, so determining battery health should be a piece of cake.

So all-in-all a happy ending. Except for the broken NAV, my Volt is still flawless.