That higher charge rate is what is expected of cars before current hybrid issues. Some may wish their h models would charge in that range while driving all the time to maintain a higher state of charge (current 12V issues may be related to batteries state of charge not being maintained). Since yours is charging at a higher rate it shouldn't hurt anything but there's always the possibility that the battery's lower state of charge is requireing a constant higher charge (i.e. the battery is getting too low for some reason)? Maybe nothing but keep an eye on it in case there is a parasitic drain or a bad battery. But I defer to the more experienced instructor level folks.

My experiences with the RX450+ 12v system.;

The battery and 12 volt systems in the vehicle are charged/powered by a DC/DC converter that draws from the traction battery. It doesn't matter what driving mode the vehicle is in, EV, HV, Auto EV/HV, or Charge mode. It always charges the same. As best I can tell from watching the battery monitor app, it charges the battery any time the vehicle is park and in Ready mode. By "charging," I mean the voltage goes over 14v. After putting it in drive, it may charge for a few minutes, but then drops voltage to the point where it is powering the vehicle, but not charging the battery(less than 13v)

Occasionally, I'm guessing once a month, the charging system will actually charge the battery (provide over 14v)while driving. It seems to be all time based and not voltage based. I've also seen periods when the system will provide greater than 14v for longer periods, this seeming to be due to very high or low ambient temperature as one sees on the hottest days of summer or coldest days of winter. The only other time the system charges the battery is about 5 minutes after remote start and for the next 15 minutes, until the remote start times out.

I put the vehicle in park any time I am stopped for more than a minute or so, and use Remote Start religiously when on road trips. This has resulted in the battery keeping a higher state of charge, though still not fully charging. At home, I use an external charger as needed to keep the battery above 12.4 volts resting.

update: I connected the Noco gen5 for 24 hours. Now it’s back to “normal” behavior, 12.8 for most driving.

Good tip on useing park to get extra charge. In regards to WellsB observation of higher charge rate based on time like once a month; a contributer (can't remember who) posted a list of factory algorithm charging boosts: like every 20hrs driving time, ambient temperature parameters as you stated, low charge and others. Really good information. If Kent experienced one of those time based extended higher charge rates he's good to go, otherwise time will tell if the battery is failing, or another issue has emerged.

If those that are sitting in "Park/Ready" mode to charge their 12 V with the car, in you are really into this - I can suggest trying another hack if you might be doing this - stay in "Reverse" mode, while keeping the brake depressed. I incidentally discovered multiple times while backing into my garage, that this leads to higher actual charging voltage for the 12 V - I noticed, charging voltage of 14+ V in "Reverse" mode, relative to "Park/Ready" the voltage was 13.2-13.7 V. Of course, the strangeness of doing any of this is not lost on me.

However, I don't do any of the above for charging my 12 V - I simply normally drive my car about 150 miles each week, which leaves the 12 V battery at 12.3 V of resting voltage. I don't trickle-charge, never for the last 6 months - unless I'm away from the car parked at home for a week or longer. I never had any parasitic drop in my car. I also have the factory/stock 12 V battery that tested good at the dealer last Dec, despite two deaths in April 2024 time-frame (after my car had survived 26 days straight of being parked fine). I'm okay with having to replace the battery either under warranty or on my own dime if no longer under warranty.

The only necessary insurance I have is the Adult Diaper (aka Emergency Start for $100) for peace of mind from "accidents".

I have a 2025 RX 450h+ . 2 days after taking delivery of this new car (I had 180 miles on it including about 150 miles with ICE) I was setting up the HomeLink and Digital Key while in my driveway. I went to exit the car and the alarm went off. Could not get the alarm to stop. Exited the car and waited. Locked the car to see if everything was Ok, and could not get the car to unlock (I was locked out). FOB (both of them) did not work, Smartphone APP would not unlock. I tried the mechanical key, and it would not work (it also needs power). Called Lexus who sent AAA to unlock and jump. Just before AAA arrived, I was able unlock the rear hatchback door (by holding the FOB near it I think), I was able to crawl in and unlock doors to pop open the hood for a jump. However, AAA had to attach to the 12V battery in the back of the car to actually get the car to start. I took the car to the dealer right then. They looked at it and said the 12V battery and alternator charging was fine. I now have a jump battery in the car just in case. Was very unhappy the mechanical key would not work, but at least the rear hatchback door worked (I think similar to instructions for my Subaru; hold the FOB near it and use the mechanical push latch on the rear hatchback door). I will try setting up the digital key again, and if the problem happens again I know to discontinue its use. Not sure about the HomeLink garage door opener, but can use a hand unit for that. I will also send an email to the salesman and branch manager about these threads (maybe the dealership does not know, and can inquire with Lexus).

The branch manager wrote back to me stating: "...the reason why you were not able to start your car is it was left in EV mode and it drained the battery. " So, before turning off the car (or sitting in it for 20 minutes learning/programming, make sure it is not set to EV mode?

When you used the mechanical key, did you try the manual release handle too? I've used it and it works fine.

I could not figure out the extra hidden lever on the bottom of the door handle after using the mechanical key. Now I understand.

@Harringtm , we have programmed and used the Homelink garage door opener on our RX450H+ for a couple of months now and have had no issues.
Based on comments In this thread, we have not set up the digital key.
Let us know if you get any feedback from your dealership, regards.

This misleading and bad information and advise - as another forum member said, this is evidence of deliberate gaslighting by dealers. Having in EV mode or HV mode has nothing to do with the 12 V battery. The only thing you want to avoid is not have the car in Accessory/ACC mode when sitting in the car.

Also, the above experience demonstrates the reason why talking to dealers or Service Advisors is a worthless exercise. Complete waste of time.

Yeah, it's ACC mode that kills it, not EV mode. The first time we killed it, i had accidentally put it in ACC mode while setting preferences.

Sitting in park in EV mode actually charges the 12v battery very well.

I think you are right. I remember now that I had the car in ACC mode while setting up the new car, only for about 20 minutes. So, I did the same thing you did, and I think that caused the battery to die. I have now disabled ACC Mode and Digital Key. I have also ordered a Bluetooth battery monitor. We’ll see how it goes.

Do you mean an OBD reader? Which one(s) work with this PHEV?

No, I am going to try ANCEL BM300 Pro Battery Monitor to try to keep on the battery and see what type of readings I get.