Okay. Who HASN'T had a 12V battery issue with their 2023-24 Prime?

I hope it is not 12.0 V because then your battery is about to die.

As I said, read the voltage when the car is off and not driven or charged for at least half an hour. Then, you can use the table above to find the corresponding SOC.

 

If you had a monitor you would see what I am saying.

 

I see what you are saying.

You have never answered my question: What are your voltage values to 0.1-V accuracy when the car is off and not being charged for at least a half hour?

 

Green is prius, other is truck. 0 on bottom scale is midnight last night. About 2:20 am the charger finished. Then the volts are shown until I went somewhere about 10 am. Soc was 100% until I went somewhere about 10 am. I think it reads about every one second on the real time graph. This one is May 17. A bar can be dragged to show the time and data. At 2:23 am the volts are 13.35, charging. At 3 am 12.92. At 4, 12.89. At 5, 12.87. At 6, 12.85. At 9, 12.85. At 9:59, car is turned on, 12.55. At 10 am, 14.28 charging by traction battery. The truck was quite steady at about 12.6 v and 92% soc stated. Until I put a charger on it whenevervthe graph shows.
.

 

Those batteries are both at 100% SOC. Prius battery has a higher voltage. That could be because it has a more concentrated acid (is it AGM?) or it is newer.

You need to measure it when there is no current. Of course there is going to be a large downward voltage spike when you start even a hybrid because you are firing up all the electronics before the DC–DC converter kicks, which draws a large current from the battery. That's why even a hybrid won't start when the SOC is too low, as you still need a large CCA to fire up the electronics initially. Then, the DC–DC converter kicks in and it starts charging, and you see the upward voltage spike.

That's why I was saying that 61% SOC you were talking about was wrong. Your both batteries are charging to 100% SOC.

 

The 61% was another time. You have to read what I said about soc, my screen capture is voltage. The graph is showing the charging on the left, then charging completes, then at 10 am I started the car. The soc read 100% until I started the car as I would have expected. The truck was not at 100% charge according to the table you provided. It has been charged now to 100%.

 

You said the following, which didn't make sense:

After seeing your data, your batteries are healthy and charge to 100% SOC; so, I still don't know know what you were talking about earlier.

Again, you need to measure the SOC when the car is off and not being charged for at least a half hour. That 61% SOC still does not sound correct. There must have been a current being drawn or some incorrect assumption when calculating it. That under 13 V sounds like the float voltage keeping the battery charged without overcharging it while driving, and it is normal. The float voltage in a 45-℃ underhood should be about 12.9 V. The SOC was probably 100%, not 61%. Remember that Gen 4/Gen 5 Prius/Prius Prime has a very smart battery sensor, and it will optimize battery charging according to SOC, temperature, etc. It certainly won't let the battery sit at 61% SOC, which would be detrimental to it.

 

I said battery may not be fine as in it isn’t fine to leave it at 61%. A person can drive around , but their still healthy battery is actually in a discharged state.
This is what most of the many 12 volt issues are about, the car not charging the battery enough. That’s the context of the thread.
I show the screen shot as you keep saying to check the voltage 1/2 hour after charging, and I show you much more data than that I collect after charging. You keep telling me to check 1/2 hour after charging anyway. As you see the check after 1/2 hour is inferior to the whole night of data.
On the trip at 61% soc the battery wasn’t charging while driving. that’s what I am trying to get the answer for. I don’t like my battery low. At other times the system does charge the battery up.

 

Well, piggy backing on what others have said, speculation is what we have and I have had 3 different batteries in my Prius. This time I permanently hooked up a battery tender - the NOCO 2D. I plug in my traction battery charger every night and also plug in my NOCO. In the morning the traction battery is at 100% and the 12 Volt battery is greened up as well. This is now the longest I’ve gone without a 12 volt battery issue. That said, it was a $39.00 expense I should not have needed on a new car (car of-the-year no less).

 

zero issues with my LE.

 

Just got back from 2 weeks away and the Prime sat the whole time. Started up no problem today when I went out.

 

This guy had a battery drain in his GR corolla and found a GPS tracker/lojack that he didn't ask for installed in his car by the dealer.

 

Wow. Would be interesting to know how many folks who have had 12V battery issues have something like this installed. I can understand having a tracker in a leased vehicle or in areas where car theft is a major concern.

 

It's a growing trend for dealers to install them for their own insurance. Some then sell it to the buyer. Others never mention it, and leave the equipment in place.

 

I just joined the dead 12V battery club. Not sure if this is relevant but the I had driven the car on the highway for about 2 hours each day for the previous 3 days and all seemed well. Then I plugged it into a public level 2 charger for about 1 hour which brought the battery up to 73%. Next morning, approx 10 hours later, dead battery. 3 days later, dead again.

 

hard to say, but might be the software bug. that's how bugs work.

 

i would think (hope) anyone bringing their car in for 12 volt problems, that the dealer service department would be smart enough to look for any aftermarket devices, but i wouldn't count on it.

 

The charging ECU battery drain TSB hasn't been properly mentioned on this thread yet - Hammersmith spotted it over here.

"Some 2023 – 2024 model year Prius Prime vehicles may exhibit a condition where the 12V auxiliary battery charge may deplete due to the plug-in charge control ECU not entering sleep mode when the Plug-in Hybrid Electric Vehicle (PHEV) charging cable has an extended connection without charging (for more than two hours). The plug-in charge control ECU has been modified to reduce the possibility of this condition."

There's a firmware update the dealer can apply with Techstream.

 

Ok, so a couple of comments regarding this TSB - I just looked at the June 13 invoice from Toyota and mine says ‘software up to date’ so no update was applied unless it was an over the air update.

I’m convinced that there is another issue involved here because I absolutely never leave the charger plugged in after the traction battery hits 100%. I am in a condo so I use only public chargers nearby and usually pull the plug either early or at most a few minutes after it stops charging.

 

a few peole have said that