And therefore, I feel incredibly "lucky" to be a 450H+ owner, as I have a lesser evil to deal with

+++++++++++++

While I hate to guess, I will point out an analogous question I recently dealt with - as I considered whether I can safely apply a colorless UV/IR blocking film on the windshield (colloquially known as a "tint", except there is no color in it) - and the Lexus manual explicitly asks not to, without stating reasons or precautions. That manual's guidance got me very worried and led me to research the "why" quite a bit (created a thread on that), and as it turns out - careful application of such a film, taking care to avoid all the ADAS sensors by an astute applier of ceramic film meant for windshields, works just fine with no problem at all. So the lesson for me is yet again that Lexus is far too concerned with its own convenience than to focus on customer convenience at all. So you know what my analogous answer to your question would be.

 

I was taught that the reason to use a ground point away from the battery to jump start was to reduce the chance of a spark causing a battery explosion. After all of the other connections are made, the last connection is the one that is away from the battery.

In the case of a rear mounted battery with underhood jump points, that is not a concern, but one still wants a solid ground point. Lexus could have easily provided one within easy reach of the positive jump point, but they did not.

 

I was taught that caution as well, but using a ground point a foot away from the positive point has never caused an issue...especially (as mentioned) with the battery being in the cargo area.

 

I have a RX450h+, I have had 3 battery failures at temperatures of 80+, 1 of them in a parking lot at 110. The last failure was yesterday. The car is less than 6 months old. All 3 failures were in stationary vehicles. The average age in my household is 91. I am physically afraid of driving the car myself and, for sure, no longer carry my wife who is a semi-invalid. The temperature in Las Vegas is 100+ for the foreseeable forecast. Dealer has no idea what is causing problem

 

I do not know how to respond except to recommend opening a case with Lexus corporate, and ask for a Lemon Law buyback by Lexus of your car. I have read reports here that folks have been successful along that parth. What you are experience is heartbreaking and unacceptable.

When I reported similar horrid reports above in the forum, folks who seem to be "Lexus brand ambassador"s told me off that these are stories of "attention seekers".

 

I feel your pain. I had three failures on mine which is 3 months old. Every time Intook it back to the dealer, they replaced something. Last time, my dealer said he is certain he will see me again. However, since then, over a month had passed and the car is behaving. The only thing I did was to deleted the Lexus Apps and digital key completely from my phone and iPad. Who knows?

 

Have you actually used it in your Lexus? (From necessity)

OK I'm going to try that. Did you have any failures while driving? Did anyone else on this thread have failures while driving?

Have you actually used it in your Lexus? (From necessity)

I absolutely agree

To say the dealer is not helpful is the understatement of the year. I now understand why women don't like dealing with repair shops.

 

I must say the car should not die while in drive, at least not due to the 12V battery issue. The 12V does not power the drive. When my car died the 3rd time, I opened a case with Lexus and demanded they take it back. They assigned a case manager and gave me lip service a couple times. Then I got an email from them saying my claim was being processed and it would take 30 days for a decision to be made. Since then, two months had gone by and no decision was rendered. My car has been behaving. So, I did not pursue any further. I know I still have the right to invoke Lemon Law if it acts up again. In CA, Lemon law says more than 4 events of failure or more than 30 days (total in the shop).

 

Warlock, no I have not used the Schumacher Portable power pack yet as I have not have any battery failures so far. It's my "life preserver". I think this is mostly a 450h+ issue. I know there have been a few 350h and 350 owners that also have had issues but they are much less common. I think the big issue is the 12 volt battery is charged by the traction battery (hybrid battery). The traction battery only charges when the engine is on or is plugged into the the wall charger but the wall charger does nothing for the 12 volt battery. If you use the car in EV mode which is where most of the energy savings come from, it may not get enough juice going to the 12 volt to keep it charged up. It seams some 450h+ owners are charging their 12 volt batteries weekly to prevent failures. I use the Noco 5 genious charger. You should not have to do that for a 70K car. I charge my 350h every 1-2 months just as a precaution. Being afraid to drive the car or transport your wife is unacceptable. Given you household age and local extreme temperatures this is down right dangerous. I would agree with Wrinkle's suggestion for a Lemon law buyback from Lexus. Good luck and I feel bad for your anguish.

 

I was on vacation for 15 days leaving the car in the garage not plugged in. When I returned home, I expect a locked up dead car. To my surprise, battery showing normal voltage with no juice loss. I also have a portable jumper charger which I carry in the glove compartment. However, I make sure if the battery dies again, I would call Road Side so that a failure is documented. That helps to build your case if you need to invoke the Lemon law some day. Jump the car yourself or connect to a battery conditioner is exactly what Lexus likes to see. You create a work around to life support a 70K car which obviously has some defective issues.

 

Ours just went five days only dropping .2v and only having one or two voltage dips per day, even when parking in a spot that usually causes a rapid discharge.

Not sure if it had anything to do with the change in behavior, but I had left it on the charger for four days . During that time, I could see the usual big spikes down, even though it was on the charger. I usually just leave it hooked up for 24 hours or so at a time.

I'll still keep an eye on it as I expect it to resume its erratic behavior.

 

To anyone with an RX450H+ invoking lemon law, here is a report of a NX450H+ owner whose Lexus case manager themselves have suggested invoking Lemon Law.

I was doing my 5 K mile service recently, and told my Service Advisor that I've had two incidents of dead battery, which I had myself resolved by jump starting. The SA's genuine response was to "occasionally drive on Gas/Hybrid mode so that the 12 V battery gets charged" - not that they did not care, but that's what they genuinely thought would actually solve the problem (the SA was otherwise excellent, and wasn't giving me lip service). Those that are new to the thread - the SA did not even understand the problem. They are not even being trained to expect the problem and suggest a solution, by Lexus.

I really hope this starts getting wisespread press and/or legal attention, so that it hits Lexus where it hurts, really bad - financially, legally - and are forced to act.

Meanwhile, we have to take care of ourselves.

 

My experience with service advisors has been universally poor, when it comes to real issues. Even when there is a TSB, I've always had to print it out and show them. When I brought up the dealer customizations at the 5k service, the SA didn't know what I was talking about, even after showing them the printed copy.

The only l workarounds I've found, so far, for the poor charging algorithm,(besides using a charger) is to either sit with the vehicle in park and the vehicle "Ready" for a while, say 15 minutes twice a week, and/or use the remote start option a couple of times a week for the full 20 minutes. (Takes about 5 minutes before the full charge voltage starts) Even that wouldn't save one from a random sudden discharge like I've experienced though and still won't fully charge the battery.

 

If you or anyone else can answer the following question that put me in bad position after I found the car dead on Friday 6/21: After the 2nd failure I put jumper cables in the trunk. After I opened the driver's door I found I could not open any rear doors or the trunk door. I am physically incapable of reaching the inside rear door openers or climbing over the seat into the back. I felt as if I was in a 3 stooges movie (and I was Curly). From the handbook I could find how to lock the back doors but not to open them. Does anyone know how to do this?
I bought a Schumacher on Amazon and got it in 8 hours. Thanks. I'll make sure it's in the glove compartment. My thinking was: Do I want to die of heat stroke for want of a $100 item? No. I hope the glove compartment doesn't auto lock.
Thanks to all helpful posters pcm888usa,jahnjva and wrinkle in particular

 

The only way to open a rear door with the battery dead is to pull the inside rear door latch lever twice.

The only way to open the rear hatch without power is from the inside and requires one get to the rear cargo area and use a procedure from the manual which requires tools.