u/GravlBike4Me

(Posted this in another thread on this channel regarding 12V battery issues. Reposting here for visibility, so please excuse the cross-post).

AN UPDATE:

Got the car back yesterday. The dealer replaced both the DCM and 12V battery. The DCM took almost two weeks to come in, and the battery was a more robust one with about 540 cold-cranking amps vs. 345 in the original car. He said the new battery should be more resilient to deep discharging, which happened three times and ultimately led to the original battery failing a reserve test.

He monitored voltage drain on the 12V after the installation was complete and saw it was stable at about 30mA per hour, a nominal amount and nothing like the 2A drain he saw with the original DCM.

There were some over-the-air updates that needed to occur to link the new DCM to my driver profile and Lexus account, which happened (almost) automatically when I had the car on the road. Nothing kept the car from being drivable, just that some of the profile configurations I created weren't immediately downloaded.

I let the car sit for about 15 hours between last drive yesterday and first drive today, and it started up fine.

He does want me to "stress test" the car a bit to see if ordinary use of the app, keeping the keys outside a tin can but more than 10 feet from the car, and keeping the car unlocked in the garage cause anything unusual or resume the big parasitic drain we saw.

One interesting bit he added is that Lexus is very aware of this and is waiting for enough service case reports to come in to justify a service advisory and campaign.

He did say that they found that certain utility company apps drivers use for finding the least expensive time of day to charge have been found to wake up the DCM and keep it awake. While that wasn't the case with my car, I wanted to put that here as another thing for drivers to watch for.

As a bonus, he disconnected the in-cabin beeping when the car backs up and confirmed that my car isn't caught up in the ECU service campaign.

I hope folks on this subreddit find this helpful. I'll post more if anything occurs or if this seems to have resolved the matter for me.

I've posted a few times here about multiple 12V battery failures on my new RZ (purchased at end of April). On my 3rd trip back to the dealer, I convinced them to keep the car over the weekend and do a draw test on it starting Monday.

The good news (!) was that the battery was dead on Monday morning, so they were in a position to observe the failure and start working on a diagnosis. Here's an excerpt from the email I got today from the service tech working on the car:

"...I was able to witness a 2amp draw which would fluctuate between 2amps and 1.6amps.  I checked to see if the vehicle was sending out any information via service connect which was causing the spike.  At that time, it did not appear that it was.  I went ahead and pulled the DCM fuse and saw the drain drop and settle at 30ma.  I left it like that overnight and came in today with 12volts still on the battery and a 30ma draw which is acceptable.  I have the fuse back in now and want to see if I can get it to happen again and may leave it like that overnight to see if my findings result in a dead battery.  I have a DCM on order as of yesterday with an ETA of Thursday, however this could change.  I will keep you updated..."

I'm going to ask them to replace the 12V battery as well, as that's gone through three deep discharges in less than a month.

I know other RZ owners are experiencing this as well and that this extends to BZs and Solterras. If you're one of them, I hope you find this info helpful

Picked up the car a month ago, love it. Went away for a week and came back to a 4000 lb brick. Can't get into the car using the key fob, key card, remote command, or physical emergency key, but I found the manual door release on the left of the handle. It's getting towed back to the dealer in the AM.

I've seen some other posts in this channel about 12 v battery issues. Is this widespread? Any common causes of a slow battery drain?