gamma742

We are talking about the HV Charger that come with the 450h+

twitte

No, my problem/issue is with the 12 volt battery going dead. There are no issues with the traction battery or my Level 2 charger that I have in my garage to charge the car. That all works great.

wrinkle

The 12 V battery goes dead if you leave the Level 1/2 charger plugged in to the car, beyond the time it takes to charge the traction battery (sounds like that's what you did ?). That's what is being said above by the folks.

twitte

I don't believe anyone above is talking about the 12 volt battery going dead from having the Level 2 charger plugged into the Lexus traction battery. The first time my 12 volt battery went dead my car wasn't plugged into the Level 2 charger for the traction battery. I think most people above are talking about the 12 volt charger being left on the 12 volt battery too long and the 12 volt battery is going dead.

NX450Guy

I think I did highlight the mysterious link between the 12 volt going dead and the charger. What happens is, charging the car (traction battery) can accidentally significantly drain the 12 battery if the charger is left in after the traction battery is charged up. Best practice is to unplug the charging cable when you’re done to stop the parasitic 12 volt battery drain leaving it in can cause. Even if you take it out and the car doors open, the 12 volt may be so drained that leaving a door open for just a few minutes could finish it off.

wrinkle

You misunderstood the posters just above - they were exactly telling you of the 12 V battery dying if you leave the level1/2 charger plugged in beyond 100 % charge. That’s not the only way to kill the 12 V, but just one of the ways. One of lsft’s videos measures/documents this phenomenon of 12 V discharge

twitte

My dealer has been testing the car after my 2nd dead battery issue. They had the car for over a week and replaced the battery. They claim it is working fine now. I get to pick it up tomorrow. Should be interesting to see if they are right.

Update 5/2/24: Dealer paperwork shows during inspection my concern was duplicated. Diagnostics check found code P05880 One. Power Draw Test Good, Charging System Test Good. Battery Test Bad (tested with Midtronics DCA 8000 Diagnostic Charging System). Battery internal failure (fails load test). Car was tested several days after battery replacement (replaced with Interstate 00544-MFH50) and no problems observed.

PS - Regarding the discussion about possible draw issues on the 12v battery with Level 2 charger left plugged into car after charging, I have been plugging my Level 2 charger into my car almost every night from about 6 pm to 7 am for the last 2 years without having the dead battery problem (until recently). I plug in and leave it because my car is programmed to charge at 12:05 am when my electric rate is the lowest. I'm not about to get up in the middle of the night and unplug my Level 2 charger after the traction battery is charged. If there was an issue with a draw from the Level 2 charger you would think that this would have happened a long time ago.

gamma742

I do the same only set me departure time in the charge schedule for 6:00 am when the electric rates go up.. My car starts charging at around midnight until 6 am. maybe the 12v are only good for 2 years?? Did you have to pay for the new 12v or was it covered under warranty?

twitte

Lexus covered the new battery. I didn't pay for anything.

Slease

Just wanted to post that I just had my 12v battery die on me. Car is a 2024 NX450h+ with 3800 miles.

Woke up one day and tried to go to work. Pressed the Start button and it attempted to start and immediately shut off. Had to get it jump started and it threw a CEL after starting up, "A malfunction in the electronic control of the engine, throttle, or automatic transmission has been detected. Contact your Lexus dealer in order to have your vehicle inspected."

The dealer wants to keep the car for a few days...will see what they find.

twitte

Thanks for the information. Please let us know what the dealer finds out. I'm really surprised that this happened to you on a 2024 model with so few miles. My car (since they replaced the battery) has been working fine. No issues yet.

NX450Guy

Very common thing with the NX 450 I’m afraid. Still surprising the dealers aren’t more on top of it. Mine died at 90 and 300 miles. The good news is that the workaround is simple and just takes a couple changes in how operate the NX. Check out the 12 volt threads on here as they cover this glitch extensively. Also, a member here has an excellent website ( https://m.youtube.com/@lsft ) that explains this and many other facets of the NX 450 you may find useful.

Cliff Notes version is the NX 450 12v battery is a bit small for all the electronics in the car. You should leave it in “ready mode” (never in ACC mode) as much as possible if you leave doors open or take short trips that prevent it from recharging fully. Occasional 15 minutes sitting in the driveway in READY MODE should do it.

As long as you don’t have parasitic draw (like from a dash cam), your dealer will say there’s nothing wrong with your battery. In that case, just a couple adjustments will keep the battery from dying again.

mpzbelmont

My NX450h+ 2024 has 8000 miles and was dead to the point where I couldn't operate the doors. To open the hood and jump the car, the door had to be pried slightly ajar and the door lever opened manually because the physical key will unlock the car but does not actuate the door latch. Dealer said the cause of the dead battery was the system constantly reporting vehicle statistics to the Lexus servers while parked causing the house batter to drain. They are waiting for Lexus to develop a patch and I'm driving my old car until it is done. No ETA from Lexus as to when the patch will be done. That's all I know and don't have any independent info to support what I was told, but thought someone might find it useful.

Slease

Got my car back from the dealer. They recharged the 12v battery and it passed all their tests. No more CEL.

They mentioned the car must be driven everyday for at least 20 minutes to keep the 12v battery topped off. Since I have an irregular work schedule, I guess I'll be looking into a trickle charger.

twitte

When the 12V battery is dead you put your door key (from your fob) into the driver's side door (after removing small plastic piece on right of handle) and turn it clockwise to unlock the door. Then you pull the lever on the lower left side of the driver's door handle to open the door. This is a two step process that I recently found out about.

Also I was talking to a friend of mine yesterday that has a new RX hybrid. He had a dead battery recently and had it towed to his dealer. The mechanic told him that they were aware of this problem and blamed it on some Lexus 12V batteries that were from Canada. They replaced his battery with an Interstate battery (like my new one) and told him to keep his key far away from his car when not using the car. The key, if close to the car, is a problem and causing an unnecessary drain. This topic is discussed in other discussions above.

After turning your key clockwise, pull this lever to open the driver's door.