wrinkle

Seconding these questions to figure amongs us here.

Last night, there was a freeze alert in Northern California and temperatures dipped to, well, just 4 C. I was going out to the stores at 10 am or so, and found my 450h+ bricked by a dead 12 V battery - yes, finally joining this inglorius "dead-battery club". Thanks to this forum, I was prepared with my mere 44 Wh battery from my vacuum-***-jumpstarter, which I bought for ~ $50 and now can be had for $ 25 apparently, paid off. I guess the battery hadn't deep-discharged since this puny jump starting battery was enough to switch to ready-mode - although obviously there is no need for cold-cranking-amps. I kept the car running for about half hour with the ICE on - and then headed out to the store - perhaps about an hour of running the ICE that apparently reasonably charged the 12 V back up to health. The car runs fine now. I might however keep the electric charging on overnight tonight (also a cold night), just to ensure that the 12 V is not discharged again - because WellB and others found that keeping the charging on at least "floats" the 12 V voltage - although probably not charging it, going by the latest posts. Call my PHEV charging the poor man's trickle-charger - I would like to avoid hooking up a trickle charger to a $ 70K+ supposedly ultra-reliable Lexus For what its worth, while I was driving the car fine for 30 mile commutes over the last few days, I seem to have noticed that the rear-doors were not opening with touch to the handle - but using the key fob worked to open the car. Hadn't thought much about it - but now thinking if that were early signs of low-voltage output.

This is a really sad and shameful situation - to be honest - to have to go through this. I saved Lexus $$ by not calling "road-side assistance" to my home garage, and saved myself time and effort today - I would ideally have liked Lexus to replace the stock/OEM battery with the Odyssey being discussed. Of course, that's not happening - so it'd be great if more knowledgeable folks like WellsB can confirm their best guess of the "largest" reserve capacity battery we can put in - without affecting Lexus warranty - so that I can prepare for next winter.

Lexicon1

@SMartin
what Amazon battery monitor did you purchase, sounds like a great tool . Also, how did you specifically monitor the fuse voltage, what fuse extender did you use for that.

Thanks

StefanoS

I must concur with those of you that favor moving up to an Odyssey AGM battery, either a Group 47 (H5) or a Group 48 (H6). It seems that the most critical dimension is the height, at 7.5 inches, as it really cannot be any higher than that. The plastic battery compartment cover rests right on top of the two poles and any taller would cause a bulge and possibly an issue. Width is also critical, due to the battery bracket/strap that goes over the top. The length just may have some wiggle room in there on the RX450h+. I checked the battery area on my wife's NX450h+ and the length appears to be a bit more cramped in that area. On that model the battery is on the driver's side of the cargo area and it is mounted 90 degrees differently than in the RX model so, I'm thinking that only the Group 47 (H5) might fit. I just did a trickle charge on both cars last night, as I did not want go thru the dead battery crap again. I am using this voltage meter in each of my PHEV's to monitor the juice going to the 12v batteries. It only provides a reading while in the READY mode but, I have another one in the cargo area which is hard wired to the battery in order to provide a reading on battery juice when the engine is off. The LED can be turned on and off in order to not have a parasitic drain. Sorry to learn of your misfortune, Wrinkle but, I'm glad that you got it worked out.

StefanoS

The downside to the Odyssey units is, obviously, the cost.....they ain't cheap. The upside is that they are not made in China, as are many of the others in the marketplace. There are similar Chinese AGM's for less than half the cost of the Odyssey units. If Odyssey's cost twice the price, are they going to last twice as long? If so, I might go for one (or two, in my case). I see mostly favorable reviews on the Odyssey but, there are a few disgruntled buyers out there, as well. I've seen some people that tried to get warranty service on an item purchased thru Amazon and were refused, as it wasn't purchased directly or thru an authorized dealer network. (not speaking of batteries in this instance). In any event, I am still kicking this idea around.

SMartin

Lexicon1, I used this battery monitor from Amazon:


It has a nice App for the iPhone that lets you download data when you get close to the vehicle (within about 15’ in my case). It will also send you alerts when the battery voltage drops too low so you can put a trickle charger on your battery or run the vehicle to recharge.





I monitored the fuse voltage and current two ways:
(1) You can put multimeter probes on the two contact points (indents) on the back of the fuse. If there’s any current flow, the resistance of the fuse will give you a few millivolts across the fuse. You can find tabulated values of fuse resistance for each fuse value; by dividing your measured voltage by this resistance, you get the current. (2) I altered an add-a-circuit fuse tap adapter that replaces a fuse and lets you bring the current out. I added a 0.5 Ohm resistor and a return wire to bring current back into the fuse plug point. (You could just use an Ammeter to measure the current, but my multimeter doesn’t work on current measurement.). By measuring the voltage across the 0.5 Ohm resistor, you can get the current flow through the fuse. I’ll try to add a photo.

Urlik

I actually don’t see a reason to use an AGM battery in the hybrids. Lead acid batteries should last a minimum of 8 years being in the back of the car. The RX350 could benefit with one since the battery is close to the turbo and AGM handles the heat better.

jahnjva

I have owned many cars in my life so far. None of them have ever had any of the battery issues that you all are describing. My last car was a 2021 Honda CRV "Hybrid". When you spend 50-80K on a car that is in some cases is brand new, you shouldn't have to monitor you battery function, trickle charge your battery, upgrade to a larger battery at your cost. Lexus/Toyota are suppose to be the "cream of the crop" for producing reliable hybrids. I don't hear about battery issues like these from other manufacturers, Kia, Honda, Mercedes, BMW, Hyundai etc. all of whom make hybrids. I have not had any issues with my battery but my climate in VA is not as cold as up north. I wonder how wide spread this battery issue is across all of Toyota/Lexus production. Lexus/Toyota needs to figure this out!

Urlik

It could just be a bad batch of batteries. The 2016 Golf R had this issue with the second batch that were shipped to the US. All of them had the batteries fail at 2 years plus or minus a month.

wrinkle

This is more about an "under-designed" reserve capacity of stock battery - which has far too much parasitic drain due to the monitoring/sensing electronics in the car's quiescent state (parked, locked) than its designed to handle, and high sensitivity to low temperature causing voltage drops - as the reasons to consider an AGM having a much greater reserve capacity than the Lexus' stock ones. So its not about having unexpected battery failures, but to get around "expected" battery deaths due to the parasitic drains and cold temperature sensitivity of the stock batteries. The NX hybrid forums have lots of threads about these. And now the RX hybrids and direct measurements too.

There have now been reports of these problems right after the first week of delivery, to a couple months, and in my case at ~4 months age of the car.

Nitrous

If you have time/interest, I’d like to know what you used to get this information. Especially how you got a ‘fuse-by-fuse’ and systems based report.
this looks extremely useful.
thanks
doug

Nitrous

Not sure if folks have looked into this, but there are drop-in lithium iron phosphate based automotive batteries. The built in BMS’s leave the car seeing a regular 12v FLA. https://www.ablithium.ca/cars-trucks-batteries/ is just one such company. I’ve never dealt with them and obviously have no conflicts of interest in offering a link.

some companies I have looked into will happily respond to questions about suitability of their ‘drop-in’ LFP replacement.

midcow3

A bigger AGM battery is still just a band aid fix. The real problem is parasitic battery drain. @SMartin hit the nail on the head, the main problem "Bluetooth digital key receiver assembly". See his post: https://www.clublexus.com/forums/rx-...l#post11699378. Other. A sources are security systems, theft cameras, etc. Lexus did a really poor job of adding phone profiles and digital keys. And actually the solution is very simple, if the 12 volt battery discharges to a low rate, it could be charged from the traction battery ( obviously , a safety stop if the traction battery is also at a very low charge level)

Also , instruction to help level set some of the more beginner forum users , when you want to tag a forum user start typing the "@" followed by the user name and select from pull down list see the diagram below:

how to tag a forum user



YMMV,
MidCow3

wrinkle

No disagreements that bigger AGM battery would be a band-aid fix - and the real fix needs to come from Lexus. That noted, what can we owners of $70K+ bricked Lexi do, when we are now loaded with a turd of a design by "ultra-reliable" Lexus - other than apply a band-aid fix and go about our lives, until and unless Lexus releases a TSB or recall notice to dealers ?

FWIW, I had the digital key disabled in-car and still had the problem. Don't have any other security system or theft cameras installed, no aftermarket accessories like dash-cam. So yes, its all on Lexus - and we are just trying to find a way of going about lives with band-aid fixes like trickle-chargers and AGM batteries.

There's at least one person in the RX hybrid forum who might ask for proceeding with Lemon law, since he had this problem right on the first week of a RX450H+ delivered.

mike995134

Check out my post in the RZ Forum … same 12V battery problem … car has been in the shop for over 3-weeks with no resolution in sight. 😡

midcow3

Same battery problem in NX forum . more prevalent with NX 450h+. This is a fairly widespread Lexus problem among different model lines.

YMMV,
MidCow3