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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).
I appreciate your efforts in this ongoing issue. I am certain that the H5 (Grp47) battery will fit fine but, the H6 (Grp48) may very will fit also. It appears that it will in the RX450h+ but, I am not so certain that it will fit in my other car, the NX450h+. It looks to be a tight squeeze in that one.
I have not used the digital key in a while. When I look in the Lexus app it gives the option to Download the Digital Key. When I go to the car Info & Security settings there is no option to set digital key to off. Can I assume the digital key was somehow deleted and therefore it's parasitic drain would not be an issue on my vehicle?
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).
Good info!
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.
This would be in the app...
Click on profile pic on top right hand side of app --> Go to ACCOUNT --> NOTIFICATION SETTINGS
I was dreading when I saw this thread but alas... I have to add "me too" have this issue.
I picked up my 2024 RX450h+ March 30th, Feb 2024 build. I've put in 508 miles, last time I drove it was last Saturday and when I tried to unlock earlier today it was dead. I have one of those battery booster pack that I specifically bought for my daily driver (Ioniq 5 which I've had for 2 years now and never needed it). Tried to jump via engine bay jump points, didn't work, had to crawl and manually open the tailgate and connect the booster to the battery terminals, worked as soon as I plugged as the alarm went off. Drove it for about 30 miles. Let's see how long it lasts.
I'm coming from a 2021 BMW X5 45E (PHEV) which was truly a garage queen. 3 years and have driven less than 10k miles, never had any battery issue even after not using it for more than a month. I didn't want to keep it as I know repairs in the future would be really expensive. Slightly annoyed as I thought moving on to Lexus it would be problem free etc.
I was dreading when I saw this thread but alas... I have to add "me too" have this issue.
I picked up my 2024 RX450h+ March 30th, Feb 2024 build. I've put in 508 miles, last time I drove it was last Saturday and when I tried to unlock earlier today it was dead. I have one of those battery booster pack that I specifically bought for my daily driver (Ioniq 5 which I've had for 2 years now and never needed it). Tried to jump via engine bay jump points, didn't work, had to crawl and manually open the tailgate and connect the booster to the battery terminals, worked as soon as I plugged as the alarm went off. Drove it for about 30 miles. Let's see how long it lasts.
I'm coming from a 2021 BMW X5 45E (PHEV) which was truly a garage queen. 3 years and have driven less than 10k miles, never had any battery issue even after not using it for more than a month. I didn't want to keep it as I know repairs in the future would be really expensive. Slightly annoyed as I thought moving on to Lexus it would be problem free etc.
You really need to put it on a charger until it is fully charged or you will probably be facing the same issue soon, and will certainly be greatly shortening the lifespan of the battery if you don't. It will take about 8 hours to charge with an 8 amp charger, and about 30 hours with a 2 amp charger. The vehicle charging system will never fully charge it.
I had been following this thread for a while because I was in the market for a RX PHEV. However, given the dead battery issue many users are reporting, I have decided to wait until Lexus gets a chance to sort this out.
I own a 2022 (4th gen) RX 450h with 16k miles. We just came back from a 12-day trip and the RX started without any fuss. So this dead battery issue is definitely a regression for 5th gen RX.
I want to share a different perspective. My other car is a BEV (Genesis G80). G80 also has a lot of electronics like RX (including digital key), but I never faced any dead battery issue. In G80, the 12 V battery is charged when the car is plugged in and when the car is in READY state. In addition, the car actively monitors the status of 12 V battery. If the charging level drops below a threshold, the traction battery charges the 12 V battery even when the car is parked. It seems to me this particular charging logic is missing in RX.
Attached: relevant pages from G80 instruction manual.
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:
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.
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.
This is great to know - thanks for the investigations and sharing the results.
However, #4 above - I'm having a hard time understanding how #4 will help. Turning off all Push notifications in the Lexus app will turn off all Notifications from the Lexus servers or at least the querying of those notifications by the App/Phone. I figured the Car would send these notifications to the Lexus servers first (over the 4G connection) draining the battery - and then the Phone/App receive them from the servers. So to improve the quiescent battery drain of the car, I would think we should have a way to prevent the Car sending these notifications to the Lexus servers in the first place. Is there a way to do so you found ? Such as by turning off any or all of the "connected car" settings from within the car or in the app ? Did that help ?
FWIW, I have turned off the "Drive Pulse" feature from the App, so that the Car doesn't (have to) send the location and gyroscope information to the Lexus servers - which also serves the purpose of not sharing my data with potential databrokers Lexus may choose to sell them to.
This is great to know - thanks for the investigations and sharing the results.
However, #4 above - I'm having a hard time understanding how #4 will help. Turning off all Push notifications in the Lexus app will turn off all Notifications from the Lexus servers or at least the querying of those notifications by the App/Phone. I figured the Car would send these notifications to the Lexus servers first (over the 4G connection) draining the battery - and then the Phone/App receive them from the servers. So to improve the quiescent battery drain of the car, I would think we should have a way to prevent the Car sending these notifications to the Lexus servers in the first place. .
That's what happens when you set push notifications off. The car will stop sending info to the server. OR the server will stop querying the car for that info. Either way, no information flow.
The question is why this happens randomly? My neighbor bought the same model, same trim, sam color on the same day. No battery issue while mine is still sitting at the dealer waiting for a diagnosis result? Both cars are made in Japan. May be that’s what people called Lemon.
The question is why this happens randomly? My neighbor bought the same model, same trim, sam color on the same day. No battery issue while mine is still sitting at the dealer waiting for a diagnosis result? Both cars are made in Japan. May be that’s what people called Lemon.
I can offer a scientific hypothesis - the real question is for Lexus to answer under oath
All degradable items like batteries lie on a distribution of lifetime/reliability - not a binary good or bad characteristic. In other other words, the overall system design (by Lexus in this case), has to account for this distribution of batteries - some batteries will be very high reliability/lifetime from the factory, others middling, others poor - however, the charging algorithm and their designs need to account for this battery variability to ensure that any reasonable use of the car doesn't expose the owner to a battery failure. You can see by neilsarkar's showing of one way of how Genesis/Hyundai achieved this - by having the logic in the car's OS to charge the 12 V when necessary, even when the car is parked. Given the high load of all the sensors, electronics (and those "illuminated door sills", etc I was forced to pay for) by these modern cars, the 12 V battery charging and health should be carefully managed for the entire reasonable usage spectrum (unreasonable usage might be a car parked continuously for a year, while reasonable would include for 2 weeks at the airport). Obviously Lexus failed in designing the 12 V battery system properly to account for (1) distribution of battery lifetime/reliability (2) distribution of usage patterns. Hence some of us seeing the problem in the first week of ownership, others in the first couple months, and others in 6 months (or for that matter, when there is significant cold weather).
Or they could have simply sized a rather high capacity battery - but that'd have increased their cost of bill of materials (increased the weight of the car, reduced its mileage, etc) and they skimped on that.
@jahnjva Good question; if you’re not seeing an option to disable the digital key, maybe it is not on in your vehicle.. So it should not be a source of parasitic currrent draw.
@neilsarkar The Genesis (and Kia) really have a nice system that charges the 12 V battery from the traction (high voltage) battery whenever it is needed—even when the vehicle is off. This is a brilliant idea that I wish Lexus would copy!
@Nitrous Sorry to be slow in replying to your question. You can get fuse-by-fuse info on Toyota/Lexus vehicles from the Toyota Information System (TIS) database. See this link: https://techinfo.toyota.com/techInfo...tis&_nfpb=true.
You can buy a 2-day subscription for $25 and comb through it for circuit diagrams, etc. I actually did a search on the fuse of interest, then got links to many systems. Then I had to comb through each system to see if it was really on that fuse. Maybe someone who knows how to use the system knows how to do it more efficiently…
Also, thanks for your link to the lithium ion phosphate drop-in replacement batteries. That’s an intriguing possibility—lots of capacity, light weight, capable of deep discharge, long life. If anyone has any experience with these, please share it with us.
Lsft in the NX forum posted this really interesting post/video of the charging phenomena over long timeframes: It seems the algorithm doesn't have meaningful or deterministic charging - in other words, driving the car doesn't necessarily mean the battery is always charging, and while parked on an "incline" can cause it to start to charge. Now that's only for the NX450h+ from 2022 - who knows what other "advancements" have been included in the charging algorithms since, and in the RX
Lsft in the NX forum posted this really interesting post/video of the charging phenomena over long timeframes: It seems the algorithm doesn't have meaningful or deterministic charging - in other words, driving the car doesn't necessarily mean the battery is always charging, and while parked on an "incline" can cause it to start to charge. Now that's only for the NX450h+ from 2022 - who knows what other "advancements" have been included in the charging algorithms since, and in the RX
Lsft in the NX forum posted this really interesting post/video of the charging phenomena over long timeframes: It seems the algorithm doesn't have meaningful or deterministic charging - in other words, driving the car doesn't necessarily mean the battery is always charging, and while parked on an "incline" can cause it to start to charge. Now that's only for the NX450h+ from 2022 - who knows what other "advancements" have been included in the charging algorithms since, and in the RX
Yup I will also add a set of ramps in addition to my trickle charger, battery booster and quick dial to Lexus road side assistance lol. So far trickle charging every Sat seems to be working for me.
04-10-24, 09:57 AM
I have one of those battery booster pack that I specifically bought for my daily driver (Ioniq 5 which I've had for 2 years now and never needed it). Tried to jump via engine bay jump points, didn't work, had to crawl and manually open the tailgate and connect the booster to the battery terminals, worked as soon as I plugged as the alarm went off. Drove it for about 30 miles. Let's see how long it lasts.
