2011 Curious if it might be some temp sensor somewhere instead of the high power battery degrading?

Things here have started to warm up a little here. Yesterday it was 50 degrees outside and the car started in battery mode and never shifted to using the engine to make poser.

Like in the past as the weather warms up my Volt goes back to battery most of the time. I realize that when things get cold the electric mileage goes down because of heating, lights and wipers using power and understand that. But the last couple years even with a full battery it runs the engine most of the time when it gets cold outside. I have thought it was just my high power battery getting older (11+ years now).

But having a full battery and the car starting the engine running right away would not be because of a used up battery. This usually happens when the outside temp is colder that 50. It would appear to me that that there is something that is colder and needs to heat up like the main battery because after running with the engine for a while she can shift from the engine running to using the battery even when it is a little below 50 outside. Could this be some sort of temperature sensor not working correctly or something like the heater for the battery not working correctly?

Just wondering what those of you that know about these things can teach me.

Roy 2011 volt #1019