Will 11.7 on 12V cause red triangle of death?

I had checked my 12v battery in my backup car last night. It's a 2006, with a 12v battery thats less than 12 months old. (made in 6/2019) it was at 10.74 volts and still worked perfectly in the car. That 10.74 volts was measured at the terminals. The car had been sitting unused for about 2 months. If I hadn't actually checked the voltage with a meter, I'd never have known it was low. The car acted perfectly normal.

Your 12v battery is likely fine. It is more likely that your refurbished HV battery has failed again.
please explain why there's a cooling water clause in your HV battery warranty. Did I misunderstand that? Can you provide a photo of it so we could read it?

 

The voltage measured at the battery terminals will always be slightly higher than what the car displays.

The 12v battery in your car should be a sealed AGM style battery. There should be no physical way to check or add water. Do you have any paperwork on the battery? There must be some confusion, because the engine cooling system has no impact at all on the 12v battery. On a prius, the 12v battery is used only to power up the electronics. It doesn't start the engine, as it doesn't even have a normal starter motor like most cars. The big hybrid battery spins the transaxle, which spins the engine to start it..

Regardless, going only by the provided voltage readings, I'm pretty confident that your 12v battery is fine.

How much of a warranty did the HV Battery refurbisher provide? 99.99% chance the HV Battery is the problem

 

So the good news is the portion of the small print referring to cooling water is for radiator replacements only. They may have a grammatical error in there, but what they're saying is radiator replacements require that the entire engine coolant system be flushed and cleaned to maintain the new radiator warranty. This is because some people may have packed the coolant system with "stop leak" material to try to solve a leak problem, prior to deciding to get the radiator replaced. This stuff is known to clog flow passages in radiators. If the system isn't cleaned/flushed, then that gunk will likely pack into the new radiator and cause flow problems.

If all you had was a 12v battery replaced, your warranty info is in the first three lines of the small print.

Now get that refurbisher to fix his junk and you'll be all set!!

 

What does the engine coolant have to do with the hybrid battery?????
If the 12v battery is weak, you'll get various warning lights.
The hybrid fan battery only runs when the car is on, and/or running.
NO water runs across the hybrid battery, or 12v battery. The 12v battery does have water INSIDE of it though.

You shouldn't need a warranty paper for the battery, they have date codes, unless that code is older than a year.
And most have more than a year warranty. You need to check with the manufacturer about that.

I think you are confusing the warranty.
You should only use Toyota premix coolant.
If you replace the radiator, it would require the flush.
That is separate. The battery is separate. They just bunch it into one paragraph.

 

Dang.....

All my life, I've dreamed of making it to Grit's Greatest Hits......and some people get there without even trying.....

Will 11.7 on 12V cause red triangle of death?
Yes.....if it's an OCV, or open circuit voltage test.

Many people are a little confused by the whole "battery test' thing....and to add to the fun most places that have those neat machines that "really test" your battery.....and GET PAID to........(wait for it!)...............replace batteries.
How to Check the Voltage of a Car Battery | YourMechanic Advice

I'm thinking that 12.3 is a little low for an OCV test (Open Circuit Test - battery disconnected.)

"....A reading of 12.65-12.77 volts means your battery has a full charge. 12.45-12.54 volts means you have a 75% charge, 12.24-12.29 is 50% charged, and 11.99-12.06 volts is 25% charged. 11.75-11.89 volts means your battery is dead."

Remember....Priuses are voltage devices.....NOT current devices.
If your 12v vattery is more than a few years old I'd consider a proactive replacement and then get back with us.
You may also have a new electrical problem.

Do you park outside?
Have you replaced your cabin air filter lately?

That's more of a G3 thing (Don't even know if a 2005 has a cabin air filter....) but your car is 15 years old and it's "possible" that you live in a high humidity environment with maybe even some seaside salty air corrosion.
You're in the realm of "anything's possible".....but I'd ask myself when the last time the 12v battery was replaced.

 

The information below from Post #2 is 100% truth. I typically connect my trickle charger to freshen the 12v batteries in any of the Prii that haven't been driven in a while. I popped the trunk to check the voltage since it had been sitting so long. SKS worked perfect, trunk opened perfect and it measured 10.74 volts. After measuring it, I decided to see how it acted when turning the car on. Everything worked perfect. 10.74.........after turning the car off, I removed the 12vbattery to get the water out of the wells from the rain that had come through for 2 days straight. I connected my OTC battery tester and it powered up normally, but after typing in the CCA rating and hitting the test button, it would show only "BAD CELL", it wouldn't even go to the next step. Put it in the garage on the charger. Got home from a HV battery job yesterday around 630 pm and after fully charging, it tested normal and at 575 cca. Remember, The beginning of almost every troubleshooting procedure in the Toyo Repair Manual has you check the 12v battery first and if it's over 11 volts, they say continue with the procedure. If less than 11 volts, they tell you to charge the battery first before continuing.

I had checked my 12v battery in my backup car last night. It's a 2006, with a 12v battery that's less than 12 months old. (made in 6/2019) it was at 10.74 volts and still worked perfectly in the car. That 10.74 volts was measured at the terminals. The car had been sitting unused for about 2 months. If I hadn't actually checked the voltage with a meter, I'd never have known it was low. The car acted perfectly normal.

 

I just read 12.379VDC on Goofy-II a 2010 - with probably a 3-4 year old battery.

The reason I said "probably" is that it's a work car that replaced Goofy-I last year.
I measured "12.379" instead of "about 12.3" not because I'm being a sarcastic jerk (this time) but because I have to maintain large banks of lead-acid batteries as a part of my job (telecommunications) and they gave me a $600 meter to do it with (Fluke 289)
Five of my 7 offices also have standby generators, and they all have 12v batteries.

All of this makes me no more knowledgeable about Prius G2 12v aux batteries than most other people, but I do know that a < 12VDC, in circuit or out of circuit is not normal for any of the start batteries that I deal with.


My opinion only.
Current street price.... <$0.02

 

Yes it will it need to be 12v-12.9 to be working I usually have it at 12.7v.

 

As TMR-JWAP mentioned in #12, Toyota does recommend to give the battery a charge if it isn't at least 11 volts.

In my Gen 3, I find the threshold between 'car will probably start' or not to be somewhere between 7 and 8 volts; my Gen 1 was about the same. Not open-circuit, but after getting in, with the brake pump running, etc. 11.5-ish open circuit was a pretty common reading on my old battery for a few years before it actually gave me any trouble and I replaced it.

Some of the ECUs in the car have trouble codes they will set if they observe a voltage below 9.5. As with other trouble codes, if those are set, there will be lights on the dash so you'll know to read them.

 

Okay?