Thanks Droid13, my '22 350H (same as JasDmw) is showing this same pattern as well. Primarily I do plenty of short -grocery getting- type trips. 10 kms stop get some things, another 5 kms, stop pickup something etc. I'm doing 15k a year with the odd 60 km drive now and again. When I'm feeling brave I've let it sit in the garage for 4-7 days at a time without my trickle charger on it just to see how it's behaving and I'm getting that slow 'fade' of voltage drop that levels out after a couple of days. I haven't let it go much more than that for not wanting to deal with a dead and ruined battery.

This is a terrible very very non Toyota situation to say the least. Taking care of a rear view camera condition that practically will never happen to millions of owners over the course of their car ownership. Investigating the problem and all the resources that go along with it, purely for liability concerns to be sure of. And leaving this issue un-resolved, that would most likely affect 90% + of owners at some point, not to mention all the dead batteries that are piling up from being replaced, is foolish for their brand's namesake to say the least! With the only safety net being provided by the owner's use of their own pocket to buy additional components to mitigate this design flaw so it doesn't leave them stranded! Booster battery, trickle charger, battery monitor and above all 'added stress' of owning a car worth $50-70K that intentionally kills it's own battery in a matter of days!

This does in my mind, need to be pushed further up the responsibility chain here! Cable gate worked here in Canada! We have plenty of data thanks to aftermarket monitors being installed. This is really not a sophisticated complex scientific conundrum here, leaving experts puzzled by "this enigma that can't be explained by modern science" It's simply a terrible design CHOICE, not even a flaw as it's so very simple to fix! Heck if it's a hybrid, you even have a second battery to utilize!

I mean all this simply because we feel we 'need' a smart car that can communicate over the internet to help us keep our modern car's software up to date and enable us to start our car while we spend another 5 minutes sipping coffee waiting for it to warm up. I would be fine to have that done when I get my oil changed or have my snow tires installed. The convenience concern is quickly thrown out after one encounter of dealing with a dead 12 volt battery on, in most cases, cars that are less than 6 months old! And that sadly won't end there for most, it possibly will happen several times over the course of a year or so!

 

I worry more about my battery dying while having these things done. I here about people detailing or washing their car only to find that their battery died during the process.

It's ridiculous that we have to worry about a 12v battery when in the past we never had to worry about our Lexus leaving us stranded.

 

I'm one of those, killed my battery 4 times until I figured out having the fob in my pocket was draining the battery.

This is the heart of the matter. As a long term owner of Lexus & Toyotas, the expectation is they are dependable and reliable.. This issue results in the opposite, I can't reliably depend on the car starting when it's been parked for a while. What's worse, I have no idea how long that while actually is.

 

You should consider installing a Bluetooth battery monitor just to see what the battery is doing over time. In my case, I walk by my sitting NX almost every single day many times with keys in my pocket to drive car #2 on bad weather days, and my keys hang on the garage door to the house so my keys are constantly in motion, and very frequently near my NX with no discernable effect.

 

Thanks for the suggestion, but to clarify, while washing the car, I used to have the fob in my pocket. As I washed and dried it, the door locks would cycle open/closed as I wiped near the handles and the rear door. Once I left the key on a shelf in the garage, the door lock cycling stopped and the battery stopped dying.

Having to purchase yet another gizmo to know what the status of my battery is seems to me an indicator of a problem. This is a Lexus, supposed to bullet proof. So why do I have a NOCO booster, a mini compressor, a steering wheel lock and possibly a battery monitor? These are all band aids we have to buy to ensure we don't get stranded. In my view, this isn't the way to build confidence in my car.

 

Ah yes, well, the whole lock/unlock thing while washing has been an issue with door sensors since day 1. My first car with this, a 2007 Camry did exactly that same thing as did my 2010 RX and my 2020 Crosstrek (which uses Toyota tech) and well as my 23 NX. But this alone never killed the battery, I feel its only because the NX battery charging always makes sure to only keep the 12V minimally charged that it becomes an issue. My colleague with a '23 NX350h told me similar stories with his, if he opens and closes the trunk more than 3 times or leaves the door open more than 5 minutes, car won't start. He's learned not to do anything that uses additional battery power without starting the car first. Sucks.

Happened to me once too, sitting in my car I was playing with something with the ignition on but car not started. I had a charger attached to maintain battery but only at minimal (trickle) setting. Within 5 minutes the car completely died. Fortunately I knew how to use the manual release on the door, jumped out and turned the charger to nuclear to bring the car back to life, LOL.

 

I'm right there with you JasDmw and others. I know we're here in Canada where the government does it's absolute best to kowtow to the auto sector. The option of submitting anything similar to the NHTSA as in the US simply doesn't exist here surprisingly. As the link mentions, they do not get involved in issues that would not be considered a safety issue.

From the website link:
Defects that we don’t consider safety-related, and therefore that we do not investigate:

paint or cosmetic blemishes
engine or other powertrain performance problems
squeaks, rattles and noises that warn the driver before a component fails
non-structural or body panel rust
air conditioners and radios that don’t work properly .... or 12 volt battery maintenance - my addition
air bags that do not deploy in less serious non-injury collisions
ordinary wear and tear on a vehicle’s parts

https://tc.canada.ca/en/road-transpo...car-seats#toc3

Now if our American brothers and sisters would like to submit something to their watchdog NHTSA that may help out.

Surely the warranty claims Lexus is seeing has to be raising eyebrows with the manufacturer! I can't wait to see what happens when the new 'smarter' Rav4 hits the streets and they are further inundated with bad batteries!

I trickle charge my battery all the time it sits! I'm sure I'll be having to replace my rear hatch liftgate struts some day because I open it every time I go to leave my house in order to disconnect the charger and stow it's cable in the back.

 

This is very interesting. I have since hooked up a monitor on a 450H+, when plugged in the 12 volt does not charge and seems to sit at around 12.4 volts and around 25% state of charge When the battery monitor is un plugged at the negative pole it seems to charge at about 14.1 volts when plugged in and reaches 100% state of charge. when driving sits it at 14.1 volts charging all the time. Not sure how many amps its putting in at that rate

 

I spoke with the dealership yesterday and have an appointment for the 20th. They are going to check the battery, no charge. Will get the 2 service/recall things done as well at that time.

They also suggested a trickle charger, but that doesn't help much when you're parked at, let's say, an airport for an extended period of time where you don't have access to an outlet to plug your charger in. Makes no sense to me that they didn't take long term parking into consideration when they calculated the load/charge duration for the battery. Seems simple engineering to me; add up the loads, determine the draw, pick a long duration for battery drain and there's your number for the battery size. But then I'm a (retired) Tech, not an Engineer.

 

What is the temperature where you are? If it is close to 0C or 32F and lower, the cars algorithm will charge the car while driving. This is normal behavior with the battery sensor. When plugged it, it will charge as I have observed that after charging and if it is left plugged in, it will charge the 12V battery for a little before it stops doing so.

 

In Mesa Arizona for the winter so temps are far from cold, When its plugged in to 110 volt circuit it charges the battery to 100% state of charge as described when the sensor is disconnected but when its connected it will only charge for a short time maybe 2 minutes or so

 

You mean the battery sensor and not a battery monitor?

 

Yes

 

Removing the battery sensor connector seems like an excellent hack for getting NX batteries to actually charge up, except for one thing... I wonder what the potential is that doing so would switch the problem from chronic undercharging to overcharging / overheating the battery if the sensor remains disconnected during a long and/or hot summer day drive. I've been tempted to try to figure a way to get the sensor to report a slightly lower voltage to encourage better, but not full on charging all the time. However, it does seem like a potentially good solution for the occasional and short trip drivers.

Perhaps when the weather is a bit nicer in Spring, I'll get my meter out and see what outputs this thing is actually providing to the car...

 

I wouldn't worry about overscharging, the OEM Battery in my 10 years old NX200T with "dumb" charging (constant 14.4V) is in better condition than in 2 years old NX350H that we also own in family hahaha
And I really mean better condition, last few days we have here -10 Celsius and NX200T started like it was nothing after night outside, but NX350H died after one night in garage wtf