I do agree the DC/DC converter failure is a rare issue - which prevents the car from being jump-started effectively.
I am reading this thread regardless of not having single issue with the car to date (9mo/9kMiles) driven in all temperatures it makes me wonder if I need the 12V monitor - will give it a try for a month and should I have some worth mentioning observations will certainly post them here.

Brgds

K

 

Someone earlier posted a portable jump starter with cables that actually were long enough to reach the negative charge point on the engine block.

Schumacher Electric SL1648 Rugged Lithium Portable Power Pack and 1250A Jump Starter

Amazon dropped the price. With the offered 15% off coupon it was $73.48 plus tax. Quite a bit less than $109.00 it was previously.

 

I know this may be totally unrelated, but I was watching you tube and they had all these Toyotas which all had small drain. If the owner didn't drive them for 3 weeks battery would be almost dead. Further research showed there was tracker installed behind the OBL connection and they were assuming it was either by Toyota, Transporter or even possibility the dealer. The device they found people put in comments is some type of GPS tracker, it was piggy backed against the OBL port. In comments people wrote they checked and some actually found same tracker connected to there OBL. They were not sure if Toyota was using it for some kind inventory tracking or maybe theft prior to selling the car, or possible Lojack component dealer would put in and not remove.

Here one of the videos very interesting, also there a lot of post on Toyota boards as well. I

 

Ours had a gps tracker on it, attached to the battery, but disconnecting it had no effect.

3 weeks is a long time for a vehicle to sit. I'd be happy if the battery would "only" last that long.

 

Let me ask you, why did it have GPS tracker on it? Who put it on and how did you find it?

 

The dealer put it in. It was an optional service to buy, but the Lexus app makes it redundant. I had expected them to take it out when we declined, but they did not.

 

I like the Lexus app tracker so if your car gets stolen, it can be found. I have no idea if I have another dealer installed one? They didn't try to sell me Lojack and the car is not leased or financed. I don't know why a dealer go through the time and expense to put a tracker on a cash sale. I thought most new cars have a manufacturer installed one? If you watch FBI and other cop shows on TV, they always seem to be able the track the criminals on newer model vehicles.

 

This is great information to have. Below is the picture of what my OBDII port looks like, and there is a LED that is lit greenish-blue and ON when the car door is opened without having turned on accessory mode or Ready mode to on.

Does this look what a stock (i.e. without dealer having messed with OBDII port) to those with a 5th Gen RX, preferably a 450H+ ? Does this LED attachment look normal ?

I haven't opened up the plastic attachment yet, so looking to compare with others first. The port, when insert my Bluedriver dongle, is NOT firm, but the entire assembly is not firmly attached at one end, so it doesn't look like the squishiness being talked about in the video (?).

 

I was listening to the radio for 10 mins with the engine off and the battery died. When AAA came, the doors had locked themselves. The backup key would not turn in the slot after I had opened the small thing on the door handle. AAA had to open from the inside with a tool. He was able to jump the battery through a lead under the hood. I am wondering if the OEM battery is too small, as others have noted. 2023 RX350h, 15K miles. It was a painful process overall.

 

After 4 weeks of monitoring the battery voltage, I've decided that the primary issues are that the charging algorithm is very poor and that there are random very-high parasitic loads on the battery.

Basically, the charging system seems to be time-based rather than battery charge-based, and will keep the battery at a low state of charge in normal use. This, by itself, will result in a dead battery in a short time when using the "ACC mode." The workaround for this is to never have the vehicle on without being in "Ready Mode," which starts the charging system. To be in ready mode, one has to be holding the brake down when you press the power button. Forgetting to press the brake while powering up the vehicle is asking for a dead battery. One nice thing about using ready mode while parked is that this is one of the few times the system truly charges the battery. The other times being when using remote start and the rare occasional times when the charging system decides to charge the battery for more than a minute or two.

As if that was not bad enough, there are random very-high parasitic loads placed on the battery due to the vehicle "waking up." Based on my observations, this results from the key fob(s) being closer than 30' from the vehicle, or other devices such as Bluetooth and/or WiFi enabled devices waking up the vehicle. I've seen this type of load kill a fully charged battery in 24 hours. Keep in mind that the only way to fully charge the battery is to use a battery charger/maintainer.

 

That may be true for a Lexus, but untrue for most other makes.

 

Having worked offshore for a living, I saw plenty of vehicles of all makes and models with dead batteries after only 3 weeks of sitting. Older cars typically did better than newer cars, but not always. One learned to disconnect the battery when going offshore, if one wanted to be sure the engine would start. Nowadays, I'd use a solar charger, but I don't remember seeing them back then.

I know some vehicles will go months without issue, but I still consider 3 weeks to be a long time, and a bit of a gamble.

 

Here's how a Lexus competitor, Genesis, who effectively manages 12 V battery drain when parked - cited by a many-time Lexus owner. Given newer cars have lot many sensors and telemetry modules, this is a no-brainer from design standpoint, especially in a modern EV or PHEV having a large traction battery. I wouldn't have any reason to believe such a design can't handle 3 weeks of being parked, and it wouldn't need to be babysit, even if the 12 V charging algorithm were deficient as Lexus obviously has.

 

The RX450h+'s traction battery has roughly 20 times a much usable power as the 12v battery, so yes, if Lexus would implement automatic charging, it would easily make it last much longer than it currently does.

It could also be accomplished by having the vehicle go into a persistent sleep mode when 12v battery voltage drops below a certain voltage.

 

This failsafe mode could easily be accomplished with software to not leave you stranded. There could also be a notification alerting to the low voltage since the DCM likes to transmit anyway. Maybe it's too logical to do this.