Help me out here.

Gonna have to disagree. A low 12V can cause bad readings in a few areas and often sends people down a rabbit path. You want to me sure the 12V is up to snuff before you trust your code reader. Once you're sure the data is accurate, have at it. Sometime back, @ChapmanF gave a list of the things a low 12V triggers, but I can't remember the details.

 

Well, these things happen. That's why they have a warranty.

If you JUST use a volt meter on the battery, with no load, you could get 12.6 or above.
Put any load on it and it could drop a lot. Voltage and amperage are different.

NO ONE charges the 12v batteries, they just get them, and sell them. Unless someone complains.
Then they will charge THAT battery after the customer complains.

I KNEW I would have to charge it when I got mine I brought my charger and vom.
When I measured it before I installed it, it read 12.7 or 8. I was surprised. I didn't think I had
to put the charger on it. Until after I installed it, and pressed the start button. And the lights barely
come on, and the hybrid warning came on. So I put the charger on the battery, I didn't put all the
covers on in case the battery was bad.
I charged it for 4-4.5 hours at 2.5-3 amps. I had to go somewhere so I couldn't do it longer.
I removed the charger, put all the covers in place, pressed the brake pedal and then the start button
and it readied without a problem. Drove for 20 minutes, it sat for a while then 20 minutes back.
The next morning I drove 3 hours home. I put the charger on it overnight. It's been working ever since.

A weak 12v battery can, and will cause problems with any modern car. Lot's of computers that NEED a
certain voltage and amperage to work correctly.

With the Prius, it seems the first place to go when lights start showing up is the 12v battery.
It's quick and easy to check. And just because it's new, doesn't mean it is fine. As you found out.

 

I would be highly skeptical of a P0A80 as a consequence of any 12 volt battery issue.

In general, I am not one of the members around here who make broad general claims of 12 volt battery issues causing all kinds of stuff.

There are certain ECUs in the car that have certain trouble codes defined to mean that the voltage on the 12 volt supply is wonky. For my money, if you have one of those specific codes, then sure, spend time thinking about whether the 12 volt battery caused it (but don't overlook other possibilities, like a wiring issue in the supply to that ECU).

Otherwise, if you're looking at some other kind of issue reported with some other trouble codes, I'm afraid it's quite often wishful thinking that sends people into a 12-volt battery cul-de-sac before dealing with the actual issue reported by the actual code. In a specific case, you might convince me with a fully worked out explanation of how a 12 volt battery issue will have caused the reported codes. By "fully worked out explanation", I mean one that shows your work understanding the exact code you have, its detection conditions, the circuits and mechanisms involved, and how you claim the 12 volt battery issue produced the result; I do not mean something general you remember from an electronics class about how supply voltage issues made things do weird things. (I also don't mean some such general explanation into which you've substituted the names of some parts you've heard of in a Prius.)

That goes double if you are trying to pin something on a 12 volt battery issue, and you've checked the ECUs that do have those codes specifically defined to mean there's a 12 volt battery issue, and you haven't got any of those.

The repair manual will pretty much always tell you to do a quick rough check that the battery ain't below 11 volts, and deal with that if it is, before proceeding with further diagnosis. That strikes me as about the right amount of emphasis to put there.

 

Can you please tell me what the "good/bad" spec for voltage and resistance values are, because I do not know what they are and would like to learn from you.

You now have a new 12v battery which looks like it was one of the problems with your car. I believe you also have a second problem which is the hybrid vehicle (HV) battery per trouble code P0A80.

So let's go back to your first post. Tell me if I am wrong, but it looks to me like the scanner attachments were taken with the HV battery at a neutral state (ignition on ?), not during high charging or discharging.

The highest blocks are #1 & #14 at 16.04 volts. The lowest blocks are #7 & #8 at 15.52 volts. So the voltage difference is 0.52 volts which might be large enough, over a period of time, to trigger the P0A80 code. When the HV battery is subjected to high charging and discharging, the voltage difference between the highest to lowest block will increase in value. So the voltage difference will be greater then 0.52v. I believe that you do have a HV battery problem.

Have you every used the Dr. Prius app? It would be very interesting to run the "Life Expectancy Test" and see the results.

I feel confidently that your P0A80 code will return. Do NOT clear the code (see post #5) and wait until you get a second code which will tell you the block that is weak in the battery pack.

 

Sorry. I didn't mean to imply that you make those broad claims. I remember that you once noted one chain of maybe 2 or 3 related codes that could come from a low 12V and it was very specific. I just can't remember which code or codes it was. It was at least a couple years ago.

 

The brake/skid control ECU has at least one specific trouble code that can be about supply voltage. C1241 is the one I remember.

The "transmission control ECU" (I always like how they use that grandiose name for the thing that controls whether you're in Park or not) also contains a voltmeter and can set at least one related code. A few other ECUs are the same way. I haven't been maintaining a list of all such codes, but they're easy enough to recognize when somebody reports having one, and you look it up.

 

If your problem stays away, then great. But I wouldn't hold my breath. On your voltage pics, I see HV blocks that are up to 0.5V difference while the car isn't ready (ie, static). Most "good" (OE) packs I see are under 0.2V, even at high mileage. Toyota doesn't publish the fail criteria for P0A80, but it seems to be something over 0.3V difference - the higher the voltage equals less time until it codes.

I don't know if your scantool can pull freezeframe data, but if it can, then the FF capture should have block voltages from when it sets the code.

 

Time for the Prolong treatment. Before it gets worst...

 

The Gen 2 Prii use a S34 (272CCA rated) 12v battery for the base model, and an S46 (325CCA) 12v battery for the models that have SKS. The extra capacity is needed due to the SKS system being active. Your Gen 3 (identical S46 model) battery tested at 276CCA, which while low for that battery, is nowhere near death and I wouldn't even be concerned if I got that reading on one of my cars. (but I would keep it in mind for monitoring/planning purposes over the next several months). The Prius 12v battery is not designed to be a high discharge/high CCA 'starter/cranking' type battery, but more of a low discharge deep cycle type battery. I noticed the paperwork states "cranking state of health". Not really applicable for our cars. The highest load our 12v battery will ever see is probably the brake actuator motor. Not all 12v batteries are created equal.....

As for your P0A80? Time will tell....I've learned that nothing is impossible.

 

The battery in your post shows a 0.08A discharge. The 12v bus is showing 11.78, which is battery voltage while the car is not in READY, so it is supplying any and all loads energized in the car (electric pumps, fans, lights, radio, etc). If it were in READY, the 12v system would be much higher, as you stated, due to the inverter/dc-dc converter doing its job. If the car was in ready, and the DC-DC was doing it's job holding the 12v system at >13.7v, how would a low voltage cause the P0A80? Did the original P0A80 trigger while driving or while parked and not in ready? Maybe I've overlooked that info.

The variance in your block voltages with only a 0.08 A discharge from the HV battery would be a concern for me. Try an app that can do a HV battery test like Hybrid Assistant, or just record the block voltages while accelerating hard from a stop and again when braking hard. Low capacity modules will show to be lower voltage than the others on acceleration and also be higher than the others during braking.

Looked back in the thread real quick, but gotta go, unfortunately. One quick question...I saw it mentioned the 12v failed on their charger. I wonder how they went about charging it? Pretty sure that model 12v states not to exceed 4 amps(or 4ish?). Wonder if it failed because they attempted the normal 16-20 amp charge rate used on "cranking" style batteries?

 

Once in a while a thread this comes along again. One feller actually resolved the same issue by replacing his 12v bat. He was ginunely pissed off when he fixed the issue after receiving numerous replies that he needed a new hv battery in the thousands of bills. His replies afterward was almost tirade like, I’ll never forget it.

 

A car that is essentially a computer with 4 wheels, a little bitty 12v battery and a charging system that is underwhelming and not upgradeable... What could go wrong with having gigawatt speakers and amps...

I CAN say I've seen large aftermarket speakers placed directly on the floor covering the HV battery create problems.
Typically, when I'm trying to (long distance) help someone with a problem, and then similar aftermarket installation information comes up further down the road, I tap out...to much variance in installation quality and much better to have troubleshooting performed in person. Long distance may as well just be guessing.

Hope it all works out for you!!