I found solutions for various older models that did not quite work, and figured out how to do it. After manually opening a rear door (manual open lever on each door handle), lower the back seats to get access to the inside of the hatch. In the lower middle is a small rectangular panel that you pop off - some people recommend a screwdriver covered in electrical tape to protect the edge. Behind the panel is an L-shaped plastic cover that you need to rotate down by catching the top left edge with the screwdriver. Behind this plastic cover is the actual metal lever that you push to the side to open the hatch. None of the other vehicles for which there is a video or instructions seem to have this plastic cover.

 

I just entered with the rear seat folded down and opened the 12V compartment without opening the hatch/trunk door. I have a trickle charger now connected and there is no need to boost or charge after that is installed. just need to plug the trickle charger by opening the rear door and fold down the seat.

 

My Trickle Charger Port..

 

@gamma742 Did you drill a hole or did you just have it pressed up against the joint?

Looks pretty awesome btw.

 

I did drill a small hole through the plastic.

 

I actually just had to go through this when my 12v completely drained. I've only had my NX 450h+ for 6 months and it was already the second time the 12v drained and first time it drained to a point that jumping it by the proxy terminals under the hood did not work. It was such a pain as I had to first fiddle with the driver door key cover to unlock the door with a key, remove a car seat in the back, crawl through the trunk, and remove the liftgate puddle light to then manually open the liftgate (Lexus should've just added a keyhole on the liftgate!). And the reason I had to do all this was because the jump and trickle charger were all ineffective.

After the jump from under the hood failed, I used a weaker trickle charger I had laying around to try to bring the battery back to life. When that didn't work, I went out and got a Noco Genius10 from a local store to give it more juice. That didn't work either.... When it was connected through the proxy terminals under the hood, it started making all sorts of clicking and whirling sounds, but never charged beyond the first indicator bar even after a few hours. I determined that the car was drawing more power than the charge (even though the Noco Genius10 is supposedly a strong charger) so I went to the trunk to disconnect the terminals from the battery and plugged the charger to the battery alone. This was the only way to bring it back to life without a tow.

Luckily, the 12v died while it was in my garage. But now I have a fear that it could die while I'm out and about. I shouldn't have to regularly keep it on the trickle charge, right??

Still have no idea what's causing the 12v battery leak. My next step is to bring it in to the dealer for the 6 month service and let them assess whether a 12v replacement is needed.

 

Is yours a 2024?

 

Yeah, 2024...

 

Haha yeah welcome to electric vehicle problems, I had the same things happened to me as well, but I do not drive my because I still drive my old car, and my Lexus is on a life support 24/7 haha (AKA smart charger). I thought that my battery is bad now and even got myself a battery tester, which showed that the battery is fine. So I hope once I start to drive my everything would be fine and I would not have to keep it connected at all, but till then it will stay connected to the life support.
Maybe instead of waiting till your next service, just take it to them now and let them check the battery, maybe you do have a bad battery like many other people have, but if the battery is good, then you do not have to worry about being stuck, just whatever you do, do not let your car sit in ACC mode, whatever you want to do like lower the windows etc. always start your car

 

Careful battery management is needed. absolutely right about ACC mode; also, be very careful about using key card. Trickle chargers also work well. But don't count on Lexus to fix the problem anytime soon.

YMMV,
MidCow3

 

Yeah, I'm now catching on that I can't leave the car in ACC mode for long due to the high battery drain. Based on my OBDII reader, the 12v battery seems to get some charge when the car is turned on, likely from the traction battery. When I'm messing around with the infotainment screen in ACC mode, the voltage would start off at low 12v and would drop below that if I stay in that mode for too long.

For those who have had their 12v replaced by the dealer, do they replace it with the exact same battery? (e.g. made in Japan, but not that it really matters)

 

My 2024 NX 450 battery also died at 90 miles and 300 miles, or less than two months old. Both times it was towed in, and battery checked out fine. Dealer kept it for three days on the last one to see if there was any parasitic drain. Found nothing wrong. Dealer was clueless. Eventually I learned that if you only take short trips, your 12 volt is not getting time to fully recharge. Then if you use ACC for 15 mins or leave a door open for too long - battery dies - sometimes quietly, sometimes with weird noises and lights flashing. A few people have had bad batteries, but for many, the 12 volt isn’t the problem. There is no warning light at your 12 volt is going to die, and it’s on the weak side compared to all the electronics it must support.

There is an easy solution, however:

1) NEVER use ACC.

2) When you are not driving but want to have the radio on, or leave doors open while working on it or washing, or anything, LEAVE THE ENGINE ON “READY MODE.”

3) UNPLUG AFTER CHARGING. After fully charged, the 12 volt will keep monitoring the car, but is receiving no juice at that point. So is draining the 12 volt.

4) KEEP FOB/KEY CARD AWAY from the NX when not driving or if not in “Ready mode.” The 12v will be used to “monitor” the car if it senses your keys nearby.

In general it seems that people who drive short hops tend to have a 12 volt that dies quicker if you commit the sins above. Just driving more or sitting in the driveway in “Ready Mode” should top off the 12v enough as long as your battery is fine.

I haven’t had an issue since I just sit in the driveway every so often after a short trip and leave it in “Ready Mode” while checking emails.

Check out this fellow forum member’s website for more details:

https://m.youtube.com/@lsft

 

Going forward, I'm only going to use ACC mode to close/open windows and start the car for everything else.

The worst part about a dead battery on this car is having to remove the little cover on the driver door handle to unlock the doors and potentially scratching it up.

 

Have you tried not to remove the cover and just pull the manual lever first? So far I never had to remove the cover yet, pulling the lever would open the doors for me probably 3 out of 4 times.

 

In both of the times the 12v died, it was parked inside my garage and I never lock the car when it's in the garage. When the 12v completely died (jump and weaker trickle charger didn't work) and I used the Noco Genius10 on the proxy terminals under the hood, it gave it just enough juice to start clicking and whirling but not actually charge (discharge was still stronger than charge), somehow, it also locked all the doors. That didn't happen when the 12v only partially died.

But yes, once it was unlocked, I used the manual levers to open the door. The physical key actually only locks and unlocks - doesn't open the door.