Hybrid Battery Drain While Driving

I have a 2016 Prius that has been operating flawlessly since purchased new.

So I am driving for about an hour yesterday and during the drive I notice that the hybrid battery shows only about 2 bars on the energy monitor, and when I came to stop at a stoplight, I pushed the throttle pedal down and the car was very sluggish but finally started moving. I saw that the engine looked like it was charging the hybrid battery, but it was still at only 2 bars. At the next stoplight (anticipating the same issue) I noticed the hybrid battery was down to 1 bar, and when I went to accelerate away from the stoplight the car went nowhere, and actually started coasting backward.

This was exciting an exciting moment since I was now in stop-and-go traffic. So I put on my emergency lights and cars when around. Finally, I was able to coast backward into a parking spot along the sidewalk.

I put the car in park, applied the emergency brake, and watched as the engine was still running hoping that it would charge the hybrid battery. After about 20 minutes in this condition, the engine turned itself off and I got a message on the dash that the "engine had turned off, electric steering was not active, and to restart the car. So I turned the car off and turned the car back on at which point the engine turned on again and looked to be charging the hybrid battery. After about 10 minutes the charge went from 1 bar to 2, and in another 5 minutes I got up to 3 bars. At that point, I put the car in drive and applied the throttle and the car moved as normal, and I drove around the neighborhood (out of traffic) to see if the hybrid battery was going to charge further.

I ended up getting it up to 5 bars, at which point I hopped back into traffic for my 35-mile trip back home. I drove fine on the freeway and all the way back home with the hybrid battery only one bar from the top.

No other warning lights of any king came on during this entire incident (I have a 2008 Prius also and have experienced the triangle of death warning sign on the dash). But nothing like that during this entire episode.

I dropped the car off at Toyota service this morning and am leaving the car overnight.

I did check the 12-volt battery using the diagnostic mode last night after getting home and noticed that the 12-volt battery charge at rest was about 11.7 volts, and when started it went to 13.5 volts. So I am thinking that this may be an underlying issue (it's the original 12-volt battery that came with the car), as I know strange things can happen with the Prius when the 12-volt battery is not in good condition.

Has anybody else experienced anything like this? Any input, comments, or observations would be greatly appreciated. I mean the car is only not only 6 years old with 51k miles, could the hybrid battery pack be failing??

Thank you in advance!

 

I am keeping my fingers crossed, but over the years don't have a lot of confidence in the dealer.
My curse is that I was a Porsche mechanic for 12 years in a former career and being very familiar with vehicle maintenance and internal combustion engines. However, when it gets into the hybrid system I am at their mercy.
Have already caught the dealer a few times charging me to rotate tires when they didn't (I marked the tires), and when doing an oil change not properly seating the O-ring oil filter canister seal (dumping oil on my garage floor at home).

 

So here's the update. I dropped the car off on Monday morning the 21st. I call at about 5pm to check on the staus, and am told by the service advisor that the technician trained to work on hybrid Toyota's didn't have time to look at my car so will need another day.

Day two, I call the service advisor at about 12pm to check on the status and am told it's being looked at by the hybrid Toyota tech. Then I get a call about 2 hours later from the service advisor asking basic questions about what I had experienced with the hybrid battery not charging. Specifically, he wanted to know if any indicators of any kind popped up. I told him no (just like I did when I explained the circumstances when I dropped the car off on Monday), to triangle or any other indicators. The car just stopped accelerating. I call him back about 5pm checking on the status, and he told me that the hybrid tech was not able to see any codes that came up that there was a problem, and that they needed to drive the car 40 miles before going any further to see if the car would repeat the performance and/or throw up codes.

Day three, I call the service advisor at about 1:30pm checking on the status. This time he sounded a little impatient telling me that he would call me with any update. I told him that I understood, but since the day was 1/2 gone and I am trying to plan my life without my car I needed to understand what was going on for planning purposes. He told me that a technician was driving my car (now I'm feeling really good about this since the technicians at this dealership are clowns) as needed in order to properly diagnose a difficult issue that exists and that is not revealing itself. He told me that he would call me as soon as he knew something.

At this point, I am thinking that the Toyota dealer better not charge me anything if they cannot diagnose what caused my car to basically die on the road, which is a hybrid system issue well within the warranty. It's 3pm now and let's see how long this goes, and what I am told.

As mentioned earlier, before I took the car to the dealer I checked the 12-volt battery that seemed to read low. I hope that the hybrid Toyota tech with all of his skill and experience thought to check this out, i.e., basic troubleshooting 101.

 

Latest update is that the Toyota hybrid technician could not get the car to repeat the event or throw a code after driving the car for 40 miles. They said that they contacted Toyota and was told that there was a software update that would likely take care of the issue. The dealer installed the software update and I pick up the car tomorrow morning, day 4.

 

So latest update is that the Toyota hybrid technician said that a recall campaign PSC-0241-17 described the same issues I was having and called for a reflash and software update, which was performed. I have driven the car now for about 80 miles with no issues, and it seems to be more consistently charging and not charging the hybrid battery than before. So hopefully this was the issue.