WellsB

I wouldn't spend money on an Odyssey battery at this time. I feel that it probably wouldn't do any any better than the OEM battery due to the fact that the current charging algorithm does not keep the battery fully charged.

jahnjva

It seems this battery issue is more prevalent with the plug in hybrid versions. (NX450h+ and RX450h+). The 350h seems a distant 2nd and not so much with the 350 gas.

Grudo

Has anyone at all reported this problem who didn't have hybrid or plug in?

wrinkle

Yes, see post by husky1055 at #29- talks about adjusting alternator and mentions 350 - so definitely not hybrid/plugin

wrinkle

The problem could also be that the PHEVs are more loaded with electronics/sensors than the gas versions or even hybrids. That's how Lexus chooses to sell them - possibly making their 12 V charging/battery design problem worse in the hybrids/plugins. And we now know of full electrics having the same problem.

StefanoS

I'm not but, it is on the back burner. It may be a better choice in the future when the current battery croaks. There is a dark current draw of some sort going on in the Lexus PHEV's and the Lexus RZ BEV models and I hope that we can get this sorted out. In the meantime, I will continue to charge the 12v on a periodic basis. I put both of mine on trickle chargers on the weekend. On Monday, I installed the same two battery monitors used by SMartin. Both 12v's were fully charged as of Sunday night. Today, when I left to run some errands, the 12v battery on my RX450h+ battery monitor read 58%. I drove about a total of 16 miles, all in EV mode, and when I returned, the monitor read 99%. I am curious as to what the state of charge will be tomorrow AM.

Grudo

Eh, they could have just left out the 'h', furthermore they never actually reported that they were experiencing the problem. Maybe someone will chime in, I'm happy to be wrong.

wrinkle

Good points StefanoS - I'm in the same situation, as I also want to not allow Lexus create trouble with the warranty if I install the AGM, so would appreciate any thoughts in that regard from everyone (i.e. would AGM battery be cited as a cause for not honoring warranty later, and also there would need to be some resetting of the computer necessary to register a new/AGM battery - so what's the best place to do all that ?). At the end of the day, I don't want to have to think about reliability issues, which is why I bought a Lexus to begin with

I'm also a bit suspicious if my battery is not holding charge (not just parasitic drain ?), as I've now measured resting voltages of 12.1 Volts in the morning after having driven the car for 30+ miles the previous day. However, I have not observed any trouble-codes in my Bluedriver-scan of the OBDII or seen voltage lower than 12 V - which is why I suspect that if I take it to a dealer they will say they didn't find any problems and will waste my time.

pcm888usa

Lexus is following the progress of my car. Since I got it on March 14, it spent more time in the dealer than in my garage. 3 visits 2 about dead locked up requiring roadside service. No word of what dealer found but Lexus on monitoring.

sailormike

I have had my battery replaced in my 350 non-hybrid. Did no go completely dead but I believe it was not far from it. See post #41 in this thread.

jahnjva

I have one of those portable chargers. The alligator connectors are are only long enough to connect to a standard battery which is in the back of the car. I would have to jump start from the fuse box and the negative metal charging point several feet from the fuse box positive connection point. Does anyone see a problem using 1 wire of a standard jumper cable to bridge the connection from the negative of the charger wire to the metal charging point?

wrinkle

I had to do exactly that (twice) and did not have any problem. Just have to be careful to not cause any shorts with dangling wires/clips.

jdct

Hello Friends,
I have a 2023 RX350 Premium, wife's car so low weekly mileage. So far no battery issues, but this thread encouraged me to check and the resting voltage was below 12v. Charged battery and all good but I suspect that it would be smart to keep an eye on the battery voltage. I have a multimeter, but the easiest solution was to get a cheap Amazon cigar lighter voltage meter to alert me when to charge. Solution is working well and I wanted to share with all of you.
Jim H

Carbuff2

While we haven't seen any battery issues (500h driven every 3 - 4 days, often only 4 miles per trip) I would think that Lexus should be capable of finding a parasitic drain source ...although replacing a battery after a deep discharge is sometimes Good Practice.

Here is a video showing how to determine current draw. I can understand how it would take days for a shop to verify and follow-up on whether a certain module is a source of this issue.
Car owners under warranty should not be expected to do these types of things, themselves, I understand...

SMartin

I’ve been on a campaign to preserve battery charge, i.e., minimize current flow when the vehicle is turned off. I had over 300 mA (0.3 A) of “dark current” before doing anything; that was draining the battery every couple of days. The following steps helped:

1. Turn off the Digital Key system on the vehicle (this was the biggie—most of the current draw in my case):
Settings -> Info & Security -> Enable digital keys -> OFF
2. Have the radio, display, etc. turn off immediately when the car is turned off:
Settings -> Vehicle customize -> Utility -> ACC customize -> ON
3. Have the lights turn off ASAP when vehicle turns off:
Settings -> Vehicle customize -> Lights -> Exterior lights: Auto off timer -> 7.5 seconds
Settings -> Vehicle customize -> Lights -> Interior lights: Auto off timer -> 7.5 seconds
4. Turn off all Push notifications in the Lexus App. This is what sends messages to your phone that something is in your back seat, doors are unlocked, etc.
5. Turning off the dome light above rear-view mirror (ok, this is excessive!)

Doing these things reduced my parasitic current to 28 mA (0.028 A) as measured by the Lexus dealer; they said this was the low end of the “dark current” spec and should be fine. And yet, with our normal driving (30 - 45 minutes per day) we could not keep the battery charged (see first figure below). My battery monitor said I was between 0 and 30% charged every day.

Then the dealer tested the battery and said it was shot (at only 6 months old). I think the constant draining of the battery (mainly by the Digital Key Bluetooth receiver cycling on/off constantly) damaged the battery so it would not take a charge, even if the vehicle was run for an hour. The dealer replaced the battery with another flooded lead-acid battery and it is doing much better at taking a charge and holding it (see second figure below). My battery monitor says I’m holding at between 70 - 95% charge with the same amount of daily driving.

This was a reminder to me that while it’s important to minimize parasitic current, that may not be enough. You also need a good battery that can take a charge! I tried to get the dealer to put in a larger battery (LN3/H6 vs. LN2/H5), but they said they can only put in the OEM size (LN2/H5) specified by Lexus. In the future, I plan to try an Odyssey H6 size with 70 A-h of capacity (vs. OEM 60 A-h). I’m also planning to put in a plug/wire to trickle charge from the outside. Figure below—any comments are appreciated. Note that there should also be a fuse in this circuit (not shown).


With original battery (6 months old) the battery voltage remains near 12.0 V (nearly fully discharged) when vehicle off.

With new battery the battery voltage remains near 12.6 V (nearly fully charged) when vehicle off.

Proposed bracket to mount panel-mount SAE connector underneath tow hitch. Trickle charger can be plugged into this to charge battery. There should be a fuse in the line connecting to + battery terminal (not shown).