Thanks for that lead.

 

Actually, the first gen 2 NX came out in early 2022 and Lexus has had more than 2 1/2 years to fix. Do you have different information that Lexus is going to fix? If so, when?

The current Lexus Corporate Answer appears to be "There is nothing wrong with your car except you don't drive it enough".

Peace and thanks for "your" contributions.


YMMV,
MidCow3

 

Thanks, TheCDN, for your detailed presentation of the products and configuration of your solution. I appreciate it very much.

 

This is still a work in progress. After the warranty replacement of the original accessory battery, we're still having rapid battery drain. So, I'll definitely be following up with the dealer about root causes/underlying issues.

 

Yes. I got a Noco 2 amp charger and have been charging at the jump block under hood. The routing out of the car in a way my wife wouldn't object to is a goal. Another goal is to see how others tackle this problem that apparently is so common to us.

 

Thanks, that's reassuring as I feel I'm on that path.

 

This is what I use to keep my battery fresh while away on a trip and left at the airport.

 

And how well does it work for you, do you know? Being inside the car one would assume that the windshield blocks a lot, and you panel would be better if it was outside but hey what do I know

 

If one looks at the Lexus Canada accessories list for the 2024 Nx350h (likely to be for other Nx years and models), there is a trickle charge accessory that has a special connector in the front grill. To quote from the part description: “…..Ensure your battery remains optimally charged even during extended periods of parking with the Trickle Charger. Featuring a temperature sensor and advanced controls, this unit dynamically adjusts charging parameters to preserve battery charge in various conditions.Fully sealed for high resistance to water and dust intrusion, the Trickle Charger shares the same bumper-mounted socket and home power cable as the block heater, ensuring convenient and easy use.” It is fairly expensive but a neat and clean solution. Called last year several US dealers but couldn’t find it in the US.

 

Here’s an idea for thought…..

If leaving the car for 3 weeks - e.g. for a holiday, what would be wrong with having a second 12v car battery in the boot, connected in parallel to the Vehicle battery terminals with a pair of jump leads?

This seems to me to be a similar situation to using a donor battery to jump start a car with a flat battery. Flaws in this idea?…🤔

PS My car is parked away from any mains electricity.

 

Would work fine and act like an extra capacity battery. Suggest matching batteries or at least close or matching capacity CCA rating. This is another band aid approach

YMMV,
MidCow3


P.S. - Parasite draw is only a partial cause not the real symptom. Real symptom programming algorithm between traction battery and 12 volt battery and algorithm and programming between MG1 and MG2. Lexus needs new engineers to help redesign failed current power convertor implementation.

The problem probably has existed since the hybrid system was first designed for the 1997 Prius. The opulence of Lexus electronics is what brought to problem out in the open.

 

In my experiences with earlier gen hybrids, the 12V circuit went to 14V and stayed there all the time the system was in Ready mode. My Camry Hybrid was traded in after 6 yrs with the original 12V, but RX hybrid was traded in after 14yrs also with the original 12V. Neither ever let me down. The difference with these two cars is zero telematics and just a simple BT radio only, no WiFi or Cell networks. The power demands of today's cars are certainly higher, but outside of the more radios and bigger screens (on the RX anyway, Camry was before screens), I can't think of anything that would create such a higher load in the current generation of hybrids? Probably more computer based modules with more processing power, but computers have also been getting much more power efficient since those days too. Outside of the potential issue of having so much of the vehicle's network stay active when the car is off, the only other thing that should affect charging while in operation would be capacity issues or perhaps, misdirected efficiency goals. The current hybrid systems seem substantially more efficient these days. My NX turbo provides about the same power and fuel economy as my RX hybrid did and not really that far behind my Camry, but yet the current gen seems quite a bit more efficient. Sure, smaller CVTs and inverters, LiON replaces NiMH and such, but energy isn't free, its coming from somewhere. I personally wonder if this latest gen has become so lean on the energy put into the 12V system and perhaps why there hasn't been any attempt to broadly "fix" this issue. Perhaps doing so means lowering efficiency a bit (gasp, shock, the horror) - and maybe why it's not going to happen!

 

Your probably right it would work better if not behind the windshield but I don't want to tempt anyone (keep the honest man honest) Seems to work well inside the car. I left it pugged in for about 3 weeks and no ill effects. People mostly use them in there RVs that sit for months with no use. The last thing I wanted was to come home from vacation to a dead battery in the long term airport parking lot. Solar powered, so it's not plugged in like the Battery Tender I use at home.

 

Nice solution

 

The Batteries, according to Lexus, would be perfectly matched - because the second battery will be the one that is going to be removed and replaced at my own cost!🤪 They have insisted on 3 occasions in the past that the battery was fine (despite failing twice) so we will see how it holds it’s charge as a stand alone battery.

The car is coming up to 3 years old and I have taken the decision to not risk a failure in the depths of a Scottish winter, rather to get Lexus to replace the battery at the 30k miles service next month. I remain of the view that the two battery failures probably did some unquantifiable damage to the cells.🤔