Third day with new car, dead 12V battery, second day in a row :(

I'm more confused , but i think I fallow you......a question: was the Prime name introduced by Toyota marketing team after the gen 4 hybrid

 

Ah, my bad! I meant Gen 4! LOL I am lost in generations. LOL

 

OK thanks , now I can take a beer and fire up the BBQ

 

IIRC, it was officially known as a Prius Plug In, commonly abbreviated as PiP(plug in Prius) here. Came out around the midcycle of the gen3. Available in about a dozen US states. Don't know if it was released in Canada.

The battery was the minimum size for incentives at the time, which meant and all electric range of 10 to 12 miles. It was meant to used as a blended PHEV, instead as an EV with a range extender.

The Prime moniker wasn't used until the gen4 Prius, and then only in North America. In other markets, the plug in Prius goes by PHV.

 

Week-old 2024 Prime owner here, and I'm having the same 12V issues as others. In my case it's caused by leaving the charger (PHEV) plugged in for 2 days.

Gen 5 will always run the battery monitor if a charger is attached, even when it's not charging. This drains the 12V battery quickly in some cases (but not for some people). Some have had it only take 24h to fully drain.


I've had a 2014 pip with the same Charger for many years without issue, so it's definitely a new concern with Gen 5.

 

Has the 12V capacity changed much through the generations?

 

So is this something that can be resolved via software, or are the 12V batteries the issue?

 

Batch of bad batteries could be the reason. Though the accessory load while parked has been growing over time, thus my question.

 

My Anecdotal Experience with the 12V on the Prius Prime

I had it happen twice in in a matter of days than never again since. I am pretty sure it recurred in my case due to the 12V battery not being completely recharged after the first time it got depleted leaving the EVSE plugged in for 6 days. I started the car after plugging in a CTEK for a couple hours to give it enough charge to start the car without the CTEK indicating the 12V battery charge was full. I than sat in the car with it running for maybe about an hour getting Toyota app all signed in thinking that would be enough to restore the 12V charge. A couple days later I had a dead 12V battery again. After the second time I left the 12V on the CTEK overnight and the CTEK indicated it was full.

I have also changed my habits concerning the EVSE trying not to leave EVSE plugged in after it has completed charging. Been about 2 or 3 months since this happened an I haven't had any issues since.

The point I am trying to make is that once it has happened once you may need to make sure your 12V gets fully recharged to prevent it from happening with better EVSE habits.

 

Not sure how I missed this thread last summer, has been a good read.

Haven’t had my 12v die (yet), however I did get a “low battery” warning about a month ago immediately after a ~2 hour drive and then parking and putting in Accessory mode for just moments (yeah, I know… just a habit since I rarely need to do this). I do have a friend in Ottawa with an XSE Premium who experienced the dead 12V after leaving it parked and plugged in his garage for a few days, and he had to boost it and reported it to his dealer.

@mountaineer , did you ever rule out one way or another if the ScanGauge II had any impact? I was planning to reinstall mine that I ran in my last two Priuses for extra data (since we lost so much fuel economy info in this car…), but of course I don’t want to increase my risk of killing the battery…

I still don’t trust the flakiness of the Digital Key - I will not leave without the fob - and with this risk of 12V dying that just further reduces the likelihood I will rely on it. Imagine if you are using the Digital Key and your 12V dies on you?

Certainly a good idea to carry one of those portable battery boosters (they are pretty small and compact these days), in case you ever come out to a flat battery…

 

Do these battery boosters harm the Prius or Prime 12 volt? They are made to produce high current.

 

I moved my portable battery jumper from my aging Porsche (which has never failed me) to the new Prime in case this happens away from home. I have a high end Xantrax Truecharger 2 setup at home, which has also only ever been used on old cars...

Related question, is there any benefit to trickle charging the 12V battery directly in the trunk vs using the jumping points under the hood (as directed in the owner's manual)?

 

Yep, as I've been saying over and over here, the main reason why the 12-V battery is draining in the Prius Prime seems to be because people are leaving the AC charger plugged in for longer than overnight.

 

You can see that the problem is the design though, right? No other PHEV would be designed to drain its 12V battery dead in 24h attached to their factory charger. Including the other pips.

I can leave my '14 pip attached for weeks with no drain.

 

No, because it's not designed to do that, and lots of people haven't had any problem.

There are enough people having issues to think that there may be a fault triggered by some factor though.

 

That's why I'm hopeful Toyota will have a solution. It is noted on page 81 of the manual that the charger should not be left attached after a charge because it will deplete the 12V battery though.

 

I watched a video review several months ago for one of the newish plug-in hybrid super cars on YouTube which I can't seem to locate now but in the video I the reviewer returned the car to a car club which was loaning him the car. The car club had several other plug in hybrid super cars and they made a point to show that they kept them all the plug ins plugged into both a 12V maintainer and the EVSE. I have since looked into a manual for one of the McLaren plug ins and they seemed to have remedied this by wiring the car so that the EVSE can maintain the 12V charge. I imagine Toyota at some point will get around to this if plug ins get more popular and they get enough complaints.

 

With stuff like this their response can be:

pay lip service at best to current generation owners, then fix it in next generation.

 

My daughter has a hybrid Camry and it's the routine to back into the garage and the maintainer is already hooked to the battery. Plug it into an extension cord and go.
I don’t think I mentioned enough yet, how about a battery monitor? It’s shown on the phone, there should be no excuse to not know if the battery is near dead. It should be part of the car.
These are brand new cars, what is it going to be like when the 12 v battery ages?

 

I've been following this thread with interest since I regularly leave the AC charger plugged in for 24 hours at a time. I only charge the traction battery 2-3 times per week at most, unless I'm on a road trip. Never had a issue with the 12V battery. I never use ACC mode, ever. There's no need to when I can just leave it in ready mode. When exiting the car, if the headlights are still on, I manually switch them off and return the switch to auto (learned that from my wife's 2014 Ford Escape as it is set to leave the lights on after exiting for a couple minutes).

A couple of things I'm curious about: Is it possible for the ACC mode to be left on after exiting and locking the car? What about the vanity mirrors? The light comes on when the cover is opened. If you put the visor up without closing the vanity mirror, is the light still on?