OBDII code P0080 or P0A80? Glitch or dying main battery?

I'm a little skeptical of my CarMD's code reader, and our local Prius service dealer is backed up for two weeks. In the meantime I'd appreciate some education and perhaps reassurance.

Seven months ago we returned from a three-month trip to find that our 2006 Prius (84K miles) had a dead Optima 12V battery. I replaced it with a dealer battery and we've had no problems since.
(Yet another thread about a dead Optima battery | Page 2 | PriusChat)
I drove it regularly up until our trip in early September and the car was fine.

Two days ago we returned from that 75-day trip while both cars were garaged for the whole time. Our 2006 Prius started with no problems and initially ran fine. We drove it a mile and parked it for an errand. (Post office mail pickup.) After a 20-minute stop I started up the car again and drove it about 300 feet when I got the master warning light (red triangle) accompanied by the brake warning light (yellow circle inside parentheses) and the check engine light.

So we drove it back home. Now I wish I'd made the time to disconnect the 12v battery cable before our trip. However we've had no problems with our 2005 Prius, which is driven even less.

I plugged my CarMD code reader into the OBDII port of our 2006 Prius and obtained two copies of code P0800 on its little display. However when I connected the reader to my PC and logged into the CarMD software, it complained about a different code:
"P0A80: REPLACE HYBRID BATTERY PACK
Generic Definition:
Code P0A80 indicates the PCM detected the difference in voltage between battery blocks in the hybrid batter [sic] pack was greater than the maximum allowable limit on two consecutive trips.
Areas to Inspect - Possible Causes:
HV battery assembly Battery ECU
Condition For Setting The Code:
Voltage difference between battery blocks is higher than standard (2 trip detection logic)"

I found this thread about a similar experience:
P0080 error. Needs new big battery per dealer | PriusChat
And these threads also seem to imply that a P0080 is really a P0A80:
Search Results for Query: P0080 | PriusChat

However I'm keenly aware that the codes could have been affected by the car being idle for so long (especially if its 12v battery was partially discharged). If that code is caused by "two trip detection logic", then it seems invalid to flag it after a long garage period followed by a one-mile trip. Ideally I'd like to drive the car for 30-60 minutes to let it go through some full cycles with the traction battery while it's charging the 12v battery. However I'm also a little cautious about dismissing a brake warning light.

I drove the car another couple miles today. The master warning light (red triangle) stayed on the whole time, but the car's ICE seemed to start & stop as expected and the traction battery seemed to charge/discharge as usual. I drove a mile up to the store, ran another 20-minute errand, and then drove home. On the way home (all downhill) the brake warning light came on, which probably indicates an issue with the regenerative braking. This trip was still very short, but I'm hesitant to drive it long distances while these lights and codes are locked in.

What if I can reset the system? If it turns out that the car just needs a long drive, is there a way to clear the warning lights before I try a longer drive? Is it worth disconnecting the 12v battery for a few minutes and then reconnecting it before driving the car a long distance? Again I'm willing to ignore false alarms, but if I can't clear them then they might also disguise a real alarm.

In the long term, what diagnostic tool should I upgrade to? I'll cheerfully retire my CarMD gizmo if it gave a false alarm, but I'm not sure what's available for the average Prius driver.

I've called a couple other repair shops and they're happy to do conventional repairs, but they don't want to touch hybrid systems because they don't have certified Toyota mechanics. In the meantime I'm calling my local Toyota dealer every morning in hopes of an appointment cancellation, but maybe I need to consider using another Toyota dealer (further away).

 

Thanks.

The Mini VCI looks like an interesting project... and a lot cheaper than the CarMD too.

Looking back through my old posts, this car seems to have a history of discharging its battery when it sits for a couple of months. (You'd expect a non-SKS car to use minimal power, but this one has given us more battery issues than our 2005 SKS model.) I don't have a battery charger (yet) but I'll check the car's display on the voltage, disconnect the + terminal for a few minutes to (hopefully) clear the warning lights, and take it for a longer drive.

 

I checked the 12v battery voltage on the multi-function display while the car was shut off, and it read 12.1v. Not out of spec but low.

I disconnected the 12v battery for a few minutes and then reconnected it. The car didn't start up correctly on the first try (it wouldn't shift out of neutral) so I shut it off. When I started it a second time it booted up properly and all of the warning lights were cleared. I had a normal dashboard.

I backed it out to the driveway and parked it. The display initially showed just two bars on the traction battery charge and the car ran the ICE for about three minutes, then the car shut off the ICE while two bars were still showing on the display. I watched the display (after the ICE had shut off) as the charge bars rose slowly to the full blue-bar count. I guess the controllers and displays were recalibrating and catching up with the actual conditions.

I left it in the driveway, turned on and in Park. I wandered off for about 20 minutes and heard the ICE running, so I returned to see how the system was behaving. The dashboard once again was showing a master warning light and a brake warning light, so the car thinks it still has the same problems. What's more of a concern is that the traction battery was showing only one bar (the lowest purple one) and did not appear to be charging.

I'll take it to the Waipahu Toyota dealer at my 8 Dec appointment (or as soon as they have a cancellation) or debate a longer drive to a different Toyota dealer.

In the meantime I'll see if I can borrow a 12v battery charger from one of my gearhead friends and repeat the whole experiment with a fully-charged 12v battery.

And for the holiday season I guess I'll treat myself to a trickle battery charger. Ideally it'll come with an air pump, too, so that I can keep the tires topped off from the convenience of my garage. It's getting hard to find a gas station with a functioning air compressor, even if I have the quarters on me to buy the air.

I ordered a Mini VCI cable off eBay: Newest Mini VCI for Toyota Lexus Scion Diagnostic Cable J2534 OBD2 OBD II | eBay
Not the best price on the site, but it's one of the few sellers who ships to Hawaii. When it arrives I'll figure out the installation and drivers on my Win7 Ultimate (64-bit) laptop. I think that version of Win7 has a 32-bit compatibility mode or I'll figure out the workarounds from the other threads on the forum.

 

After debating further troubleshooting with a 12v battery charger (or jumpering the Prius with the other Prius), I decided to let the dealer do the diagnosis. I drove the car down there and it got unhappier with each mile.

When I started up, the master warning light and the brake warning light came on. The ventilation fan for the traction battery came on at max RPMs. (I've never heard that noise before.) The ICE tried to recharge the battery for the first mile, but then I heard a "click" from under the hood and the display stopped showing green arrows pointing to the battery.

During the next six miles, most of that was coasting downhill or on the flat. The ICE ran continuously and seemed to stay at a high stable RPM. The car had little power or acceleration.

Any other issues I should discuss with the dealer's service rep?

I have an appointment for 8 Dec, but they'll troubleshoot it sooner if they have a cancellation. The service rep hasn't looked up a traction battery replacement quote for a while but thinks it's "less than $4500". With a working traction battery, the resale value of the car would be about $6200.

I'm ambivalent about replacing the traction battery on my own. I'm not sure how to find one on Oahu, and I'm skeptical of the quality I'd get from Abe's Auto Recyclers. A new OEM battery probably has a heavy retail markup, and the dealer's labor quote is only about four hours at $110/hour. I have the mechanical and electrical skills (thanks to the Navy's submarine force) but I'd rather work on other projects (or surf).

This is an interesting decision. I could blow the bucks for a Leaf, recharge it from our photovoltaic array, and never buy gasoline again. (A savings of less than $1000/year.) However I'd have to do a longboard check on a Leaf's interior. A neighbor has owned a Volt for a few years and I should ask him how it's doing. I'd have to try putting my 10'0" in there, too. Or I could just buy another used Prius.

But I'm also comfortable with this Prius. A certain amount of laziness and rationalization goes into the decision to replace the traction battery while hoping to get another 200K miles out of it. It's more than having the seat adjusted exactly the way I want it-- it's the hassle factor of finding and buying another vehicle.

 

The dealer confirmed that the codes are P0A80 and P3015, and that all of the other driving symptoms are a bad traction battery.

I elected to have the dealer do the replacement for $4375. Now the car's back to normal.