ICE continues to run when stopped with traction battery fully charged

I couldn't seem to find a post that aligned with my experience, so I'm sharing here with hope someone else may find it useful. Please let me know if I've missed a thousand threads that already cover this.

Yesterday evening, I noticed that the engine continued to run at red lights despite the battery icon showing it fully charged. There also seemed to be some hesitation when accelerating from a stop.

During some recent maintenance, I noted that the my 12v battery displayed 11.9 in the Function/Check Setting>Vehicle Signal, despite being just over two years old (DieHard Hybrid Battery). When I Googled my symptoms, I read that it may be related to a failing 12v, so that seemed a reasonable starting point …

This morning, after the car sat overnight, I checked the voltage on the 12v with a multimeter and got 12.3. Interestingly, I checked the Vehicle Signal menu immediately following and it still said 11.9.

This afternoon, I had the battery tested at Advance Auto. They said it passed the cranking amps test but failed the "reserve capacity" test.

I installed a new battery this afternoon. I will report back if the original symptoms return or if the 12v battery seems to have been the culprit.

 

Well it's been well over a month and replacing the 12v battery seems to have remedied the engine continuing to idle when it traditionally wouldn't.

 

Understood, Jeff, and thanks for the input. I'm the original owner of this vehicle and I'm pretty alert to normal vs. abnormal cycles/sounds. This experience followed a highway trip at high speed and the display for the traction battery showed fully charged, so it did not seem normal.