Hybrid battery topping out after repair?

OK, not the best subject line....

Long time lurker back to post with a question. My 2007 Prius was hit from behind by a Ford Explorer about two months ago. The damage was mostly cosmetic and I was able to drive it just fine for the three weeks it took to get everything worked out with the insurance company.

After that, I took it to the repair shop who had done work for me before on a previous Prius. They had the car for just over 6 weeks. You can see pictures here until they take them down by clicking on number 291:

Check Vehicle

As you can see, the work was mostly body work on the rear bumper, rear hatch, rear body panel, and associated structural things. They said they didn't have to touch the electronics in any significant way other than lights and such.

Anyway, they took it to the dealership yesterday because it was giving some error codes that they had to have cleared. The dealership is where I get service and I trust their techs.

Now, my blue baby is back in my possession but it is doing something strange. It seems like the battery doesn't hold a charger. The display on the touch screen goes from full green bars to two purple bars in the ~30 seconds it takes me to back out of the driveway and recharges from that state to full green again in the length of stopping at an intersection. While stopped for a light cycle, with nothing running other than the radio, I can visibly see 3-4 bars drop off the display in ~45 seconds. It then charges up again just fine with driving.

In short, it seems to cycle between empty and full very quickly. As an experiment, I sat it in the driveway with nothing no but the radio (it was in ignition on mode so I could have driven it) and watched as the battery display drained two two bars, the engine kicked in for less than 30 seconds, it charged up to full on the display, the engine shut off, and the cycle repeated about three or four times.

I've already requested information about the error codes from yesterday and waiting to hear back. I'll be calling the body shop and the associated dealership tomorrow to ask them to resolve the problem. However, I wanted to see if any of the technical experts here have any thoughts on possibilities that I should explore or things I should ask the techs when I bring it in.

Thanks in advance guys.

 

I should also note that the battery does hold a charge. I parked it showing full green bars on the touch screen display, was inside for about an hour and a half, and it was still all green when I came back out and turned the car on. Unfortunately it discharged completely over the length of my driveway.

Because of this, I don't think anything's shorting or draining the battery. However, I'm concerned that there's a sensor of some type that's messed up or else the battery has been topped out through some sort of improper charging so that it won't charge properly.

 

Actually, yes. The body shop is Woburn Foreign Auto Body and they're associated with Woburn Foreign Motors. The body shop had done great work repairing a previous injury to my Prius from Boston traffic and the dealership is where I've gotten my Prius serviced (the current one and the previous one) since I've been driving them so I feel confident that they can track down and fix the problem with little shenanigans.

However, I ask here in order to go in prepared just in case. Also, it may help others later.


The heat hypothesis has some merit in my mind. Especially since part of the repair was to replace the rear body panel which involved welding a new piece of metal to the frame in the rear of the car and I can clearly see the battery pack in the photos.

Keep the ideas coming and I'll be sure to update here with any developments.

 

Actually, they are a Toyota dealer and have several Prius technicians on staff. The dealership sells only Toyota, Scion, and Jaguar and those are the cars the body shop specializes in.

I'm most concerned about the possibility of a loose connection somewhere or a dead cell in the pack. After a quick call this morning, the theory I'm getting from the body shop guy (who claims to have talked with a tech after talking to me) is that the battery did a deep discharge due to sitting in the shop disconnected for 6 weeks. He thinks normal driving will 'charge it up again' and everything will be fine. :der: I think he's thinking it's a lead-acid battery like a standard car and will be getting a second opinion. Planning to bring it to Acton Toyota to see if I can have one of their techs take a look and give me an opinion.


One other thing that he mentioned is that there was a part that they replaced associated with the electrical system. I'll get the name from the paperwork when I'm home tonight, but he described it as sitting near and to the left of the small aux. battery in the back. Any thoughts that this brings up?

 

Well, I'm still waiting to hear back from the Prius tech who actually was the last to see the car and test run it. However, I do have a few items from the body shop's list of work that might help shed some light. These are all direct from the final invoice though the invoice doesn't give any indication as to the order in which things were done:

The full list was three pages long, but most of it was exterior body panels, glass, and paint. These stuck out though. I'll see what the techs at the dealership where I bought it (Acton Toyota) think tonight or tomorrow.

Thanks all.

 

Another update:

Called Acton Toyota and spoke to one of their techs. He said it sounded (qualified by 'can't say for sure over the phone') like the hybrid battery had been discharged to a very low level at some point during the repair process and that the behavior was from it failing to charge properly because it's too low. He said the only real solution at this point would be to bring it in, confirm that's the case, and get some sort of special charger from the regional Toyota people that they use to recharge in such situations. He said there shouldn't be a problem driving it for a day or three in this state though. I'll be calling tomorrow to follow up on this with the original dealer/body shop.

In related news, I drove the car for several short in-town trips on Friday, Saturday, and today. Today, it seems to be behaving a bit more normally. Where in the past it would go from full green bars on the touch screen battery indicator to two purple bars in about 45 seconds or a minute of sitting at a stop light with nothing on but the radio, it now takes ~30 to 40 seconds for each bar to vanish under the same conditions. It's still 'dropping off' way faster than it used to and my mileage is in the toilet - 35mpg over the past 40 miles. Part of that is short trips, but part of that I know comes from the engine kicking on at stop lights it didn't used to, inability to drive in all-electric along sections of road I used to be able to before, and the engine generally working harder during regular driving at speed.

Hopefully progress tomorrow.

 

I'm back with a final follow-up to close this out. I had the car in to the dealer a couple days ago. They could pull no current or stored codes from the computer at that time.

They did take it for a test-drive and noted the symptoms I saw and after much discussion with the tech (I didn't want to play "telephone" through the service writer and the agent at the body shop) he's convinced me that what I'm seeing is normal behavior of the battery re-charging itself after 6 weeks of disuse and a deep discharge. I'm inclined to believe this as I see continued improvement each day and the car has returned to nearly normal performance despite acting very strange those first few days.

I've got the extended warranty along with the nice long hybrid system warranty and lots of paperwork to document this issue to this event in case it ever becomes a problem in the future. Therefore I'm comfortable taking a wait and see approach for now as everything seems to be in working order.