Dead 12v battery Incident (merged threads)
03-26-24, 10:40 AM
#151
Afraid this is what we are all facing now. It's not just all the computers with the parasitic drain as in past but the DCM module seems to be what is causing a lot of the problems with constant communication. Software updates have been and continue to minimize this problem. Probably a good idea to at least keep jumper cables in car as it only needs a 12v source to go into ready mode then 14.2 volts available to charge battery.
First thing I would do is opt out of Drive Pulse, as the thing might still be running even when you stop the car and is constantly sending out updates on itself and its location.
But still lotsa connections to the outside in this car.
If you go in the app to INFO --> SUBSCRIPTIONS, you can see all your subscriptions (trials at the beginning). You can cancel them it seems, though I would not do that until sure this is what's causing it. They're all pretty cool and useful.
03-26-24, 11:53 AM
#152
Instructor
If it's the DCM then I was right in that it's the connection to the network that is causing the drain.
First thing I would do is opt out of Drive Pulse, as the thing might still be running even when you stop the car and is constantly sending out updates on itself and its location.
But still lotsa connections to the outside in this car.
If you go in the app to INFO --> SUBSCRIPTIONS, you can see all your subscriptions (trials at the beginning). You can cancel them it seems, though I would not do that until sure this is what's causing it. They're all pretty cool and useful.
First thing I would do is opt out of Drive Pulse, as the thing might still be running even when you stop the car and is constantly sending out updates on itself and its location.
But still lotsa connections to the outside in this car.
If you go in the app to INFO --> SUBSCRIPTIONS, you can see all your subscriptions (trials at the beginning). You can cancel them it seems, though I would not do that until sure this is what's causing it. They're all pretty cool and useful.
Last edited by alextv; 03-26-24 at 12:52 PM.
03-26-24, 07:02 PM
#153
Intermediate
I posted about my surprise 26 day battery survival on the 450h+ - but I will also note that I had switched off the App's Drive Pulse (primarily to avoid sending potentially misuse-able data to the wild, unrelated to battery drain) during this period.
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asj2024 (03-26-24)
03-26-24, 08:01 PM
#154
I posted about my surprise 26 day battery survival on the 450h+ - but I will also note that I had switched off the App's Drive Pulse (primarily to avoid sending potentially misuse-able data to the wild, unrelated to battery drain) during this period.
Yeah, that does support the potential of Drive Pulse (and perhaps other connected services on the car) to help drain the 12V battery.
So besides preventing misuse of your private data, turning this off can also help keep the 12V healthy
03-26-24, 08:15 PM
#155
Intermediate
I strongly suspect there are multiple factors at play (I used to get paid to do reliable system design 
, so speaking based on that experience)...
One is there is definitely defective batteries in brand new cars - such as in the experience by RBach below. And in my car, there wasn't evidently a defective battery. This is a problem that only Lexus/user can fix, by replacing the battery for those that have it. From Stefanos' experience, I suspect even he might have a defective one. Also "defective"/non-defective isn't exactly a binary categorization here, since we are talking about an analog signal coming of the battery (voltage) that leads to the problem. WellB's measurements showing the degradation, BUT him never actually having a dead battery, proves this point.
The other is parasitic drain, which is something we/users can try to mitigate - assuming the defective, shipping battery is not present in the car. While I'll not claim that stopping the Drive Pulse made a difference in my case, the not-so-cold temperature (say, relative to Canada or Northeast US) did surely make a difference, from the perspective of battery physics.
Another detail: When I had tried and failed to remote start after 12 days, I had also tried "Refreshing" the "Status" screen in the App - the "Tire Pressure" and The "Vehicle Information" one-line status dates didn't update from the day I had stopped using the car to begin with (the beginning of the 26 day period). In other words, this probably suggests it got into a deep-sleep state and did not transmit data in that state to the Lexus servers - probably reducing the parasitic drain. In normal usage, that status updates fine. Also, I don't have any after-market devices attached to the car.
I'll also add that the previous ICE car I owned (an Audi from 2014), I used to have a 4 mile commute to my work in that car for the most part - very short hops. The battery had died and had to be replaced by the dealer in 2-3 years for that too. So usage model of the battery definitely matters, as does temperature etc. - despite being a pure ICE and not having parasitic drains like a heavily computerized cars as the modern ones.
, so speaking based on that experience)...One is there is definitely defective batteries in brand new cars - such as in the experience by RBach below. And in my car, there wasn't evidently a defective battery. This is a problem that only Lexus/user can fix, by replacing the battery for those that have it. From Stefanos' experience, I suspect even he might have a defective one. Also "defective"/non-defective isn't exactly a binary categorization here, since we are talking about an analog signal coming of the battery (voltage) that leads to the problem. WellB's measurements showing the degradation, BUT him never actually having a dead battery, proves this point.
The other is parasitic drain, which is something we/users can try to mitigate - assuming the defective, shipping battery is not present in the car. While I'll not claim that stopping the Drive Pulse made a difference in my case, the not-so-cold temperature (say, relative to Canada or Northeast US) did surely make a difference, from the perspective of battery physics.
Another detail: When I had tried and failed to remote start after 12 days, I had also tried "Refreshing" the "Status" screen in the App - the "Tire Pressure" and The "Vehicle Information" one-line status dates didn't update from the day I had stopped using the car to begin with (the beginning of the 26 day period). In other words, this probably suggests it got into a deep-sleep state and did not transmit data in that state to the Lexus servers - probably reducing the parasitic drain. In normal usage, that status updates fine. Also, I don't have any after-market devices attached to the car.
I'll also add that the previous ICE car I owned (an Audi from 2014), I used to have a 4 mile commute to my work in that car for the most part - very short hops. The battery had died and had to be replaced by the dealer in 2-3 years for that too. So usage model of the battery definitely matters, as does temperature etc. - despite being a pure ICE and not having parasitic drains like a heavily computerized cars as the modern ones.
Adding another data point to this thread.
Brand new 2024 RX 450h + essentially dead on (delivery) arrival. Had to jump start the vehicle twice in first week of ownership.
Have checked daily for anything "on". Haven't found anything yet. Have tried keeping the vehicle both "locked" and "unlocked" overnight; no difference.
Brand new 2024 RX 450h + essentially dead on (delivery) arrival. Had to jump start the vehicle twice in first week of ownership.
Have checked daily for anything "on". Haven't found anything yet. Have tried keeping the vehicle both "locked" and "unlocked" overnight; no difference.
Last edited by wrinkle; 03-26-24 at 11:07 PM. Reason: Additional details.
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asj2024 (03-27-24)
03-27-24, 12:26 AM
#156
Driver School Candidate
If that's the case, I hope a simple OTA update for RX will fix any problems.
For the 450h+, I believe the 12V is charged when you do an overnight charge of the traction battery as well.
And yeah, why can't there be an icon for 12V battery life, just like there is for the traction battery.
ps. good to know about OBD2 12V readings being 0.5V lower than actual. I was wondering why the heck I was getting 11.3V for my 450h+
For the 450h+, I believe the 12V is charged when you do an overnight charge of the traction battery as well.
And yeah, why can't there be an icon for 12V battery life, just like there is for the traction battery.
ps. good to know about OBD2 12V readings being 0.5V lower than actual. I was wondering why the heck I was getting 11.3V for my 450h+
On a RX450h+, The 12v battery is not charged while charging the hybrid battery…that’s what my handy dandy Fieldpiece meter shows. Seems the 12v battery is charged only while the car is in “ready” mode. Ours is currently at the dealer getting the 12 battery checked as we found the battery at 3.9 volts. My second biggest beef with this car is the lack of an external manual rear hatch release.
03-27-24, 02:44 AM
#157
On a RX450h+, The 12v battery is not charged while charging the hybrid battery…that’s what my handy dandy Fieldpiece meter shows. Seems the 12v battery is charged only while the car is in “ready” mode. Ours is currently at the dealer getting the 12 battery checked as we found the battery at 3.9 volts. My second biggest beef with this car is the lack of an external manual rear hatch release.
https://www.clublexus.com/forums/hyb...l#post11695832
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wrinkle (03-27-24)
03-27-24, 02:52 AM
#158
I strongly suspect there are multiple factors at play (I used to get paid to do reliable system design , so speaking based on that experience)...
One is there is definitely defective batteries in brand new cars - such as in the experience by RBach below. And in my car, there wasn't evidently a defective battery. This is a problem that only Lexus/user can fix, by replacing the battery for those that have it. From Stefanos' experience, I suspect even he might have a defective one. Also "defective"/non-defective isn't exactly a binary categorization here, since we are talking about an analog signal coming of the battery (voltage) that leads to the problem. WellB's measurements showing the degradation, BUT him never actually having a dead battery, proves this point.
The other is parasitic drain, which is something we/users can try to mitigate - assuming the defective, shipping battery is not present in the car. While I'll not claim that stopping the Drive Pulse made a difference in my case, the not-so-cold temperature (say, relative to Canada or Northeast US) did surely make a difference, from the perspective of battery physics.
Another detail: When I had tried and failed to remote start after 12 days, I had also tried "Refreshing" the "Status" screen in the App - the "Tire Pressure" and The "Vehicle Information" one-line status dates didn't update from the day I had stopped using the car to begin with (the beginning of the 26 day period). In other words, this probably suggests it got into a deep-sleep state and did not transmit data in that state to the Lexus servers - probably reducing the parasitic drain. In normal usage, that status updates fine. Also, I don't have any after-market devices attached to the car.
I'll also add that the previous ICE car I owned (an Audi from 2014), I used to have a 4 mile commute to my work in that car for the most part - very short hops. The battery had died and had to be replaced by the dealer in 2-3 years for that too. So usage model of the battery definitely matters, as does temperature etc. - despite being a pure ICE and not having parasitic drains like a heavily computerized cars as the modern ones.
, so speaking based on that experience)...One is there is definitely defective batteries in brand new cars - such as in the experience by RBach below. And in my car, there wasn't evidently a defective battery. This is a problem that only Lexus/user can fix, by replacing the battery for those that have it. From Stefanos' experience, I suspect even he might have a defective one. Also "defective"/non-defective isn't exactly a binary categorization here, since we are talking about an analog signal coming of the battery (voltage) that leads to the problem. WellB's measurements showing the degradation, BUT him never actually having a dead battery, proves this point.
The other is parasitic drain, which is something we/users can try to mitigate - assuming the defective, shipping battery is not present in the car. While I'll not claim that stopping the Drive Pulse made a difference in my case, the not-so-cold temperature (say, relative to Canada or Northeast US) did surely make a difference, from the perspective of battery physics.
Another detail: When I had tried and failed to remote start after 12 days, I had also tried "Refreshing" the "Status" screen in the App - the "Tire Pressure" and The "Vehicle Information" one-line status dates didn't update from the day I had stopped using the car to begin with (the beginning of the 26 day period). In other words, this probably suggests it got into a deep-sleep state and did not transmit data in that state to the Lexus servers - probably reducing the parasitic drain. In normal usage, that status updates fine. Also, I don't have any after-market devices attached to the car.
I'll also add that the previous ICE car I owned (an Audi from 2014), I used to have a 4 mile commute to my work in that car for the most part - very short hops. The battery had died and had to be replaced by the dealer in 2-3 years for that too. So usage model of the battery definitely matters, as does temperature etc. - despite being a pure ICE and not having parasitic drains like a heavily computerized cars as the modern ones.
Last edited by asj2024; 03-27-24 at 02:56 AM.
03-27-24, 02:47 PM
#159
On a RX450h+, The 12v battery is not charged while charging the hybrid battery…that’s what my handy dandy Fieldpiece meter shows. Seems the 12v battery is charged only while the car is in “ready” mode. Ours is currently at the dealer getting the 12 battery checked as we found the battery at 3.9 volts. My second biggest beef with this car is the lack of an external manual rear hatch release.
The vehicle will charge the 12v battery if plugged in and turned on though.
03-27-24, 06:17 PM
#160
Intermediate
I verified this today. I put the vehicle in accessory mode and let the battery fall to 11.7v. I then pugged in the traction battery charger and the battery recovered a bit, but only went up to about 12.5v or so, not a charging voltage. This surprised me.
The vehicle will charge the 12v battery if plugged in and turned on though.
The vehicle will charge the 12v battery if plugged in and turned on though.
Does that make sense ?
03-28-24, 12:26 AM
#161
Driver School Candidate
Add my SO to the list of “dead battery syndrome” sufferers. After 5 days of non-use in our garage, she found the battery so dead that we shoulda dug a hole and buried it. When I returned from work, I put the booster charger to work and got the rear hatch to open. Found the battery and my meter showed 3.9 volts😱😱. Serious WTF moment. Attached my SO’s 45+ year old dumb charger directly to the battery for a good 5 hours. Once the 9a output dropped to less than 2a, I removed the charger and plugged the level 2 for the night. Next day the battery was 12.3 and within 2 days of non-use it was 11.8 Scheduled for service to check it out as the car is going in to body shop for 7-10 day repair. I gotta bad feeling that this battery won’t survive the body shop stay and some minimum wage worker is gonna jump start it and crispy critter something expensive.
Dealer replaced the battery and we have our RX back. Loaner was NX350h. Will work on the settings. I’m getting a better handle on understanding how the charging system works. One of them boosters is probably necessary to keep in the car, just not in the trunk. An external manual rear hatch release would have been nice, Lexus.
03-28-24, 12:41 AM
#162
Driver School Candidate
Thanks, good to know. Check out this thread for some possibilities. Mine is probably not defective, but I've shut down possible sources of connectivity drain like Drive Pulse.
https://www.clublexus.com/forums/hyb...l#post11695832
https://www.clublexus.com/forums/hyb...l#post11695832
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SMartin (04-02-24)
03-28-24, 04:15 AM
#163
Updating progress on diagnosing the parasitic draw on this new RX450h+ w/ the new deeper-discharge Lexus battery replacement:
Continuing to try to find things to turn "off" and "on". Latest is indeed the 'Connected Services' that Lexus offers - the ones you interact with on the Lexus app. Turned off yesterday, will let rest for 24h and test resting state of 12v battery.
Sitting still with car in "Ready" mode to talk with Lexus support and disconnect the services, the traction battery charges up the 12v to 12.61.
Also, for more info, answering these diagnositic questions from before:
What did they say the ma parasitic draw was?
[ sorry, I didn't think to ask to get that from the service technician; what I was told is after two hours of testing 'at rest', they couldn't find a parasitic draw with their volt meter connected to the 12v battery in series w/ the negative post ]
A full charged battery after 20 minute rest should read 12.7v. How many nights to attain that 11.76v reading?
[ two days essentially; from 12.6 usually down to 11.96 in first 24h cycle, then from 11.96 down to either 11.76v or even 11.43v sometimes next day ]
What kind of driving each day?
[ car is typically used every two to three days, full EV mode for about 20 ~ 30 miles, garage kept, insulated garage in Virginia, mild weather; not cold by any means; typical ambient temp 60 F ]
[[ note on full EV mode: when we drove back from dealer servicing (12v battery change), we drove 100 miles obviously using the ICE only. Running on ICE vs EV has no effect on what the 12v parasitic drain does. ]]
Are both keys far away from car at night
[ ahhh, great joke there my friend, assuming Lexus would provide two key fobs at delivery; only have one right now; have the key 100' + away from vehicle, inside a Faraday RF blocking pouch for anti-theft measure ]
and try disable the digital key in Lexus app as in background may try to communicate continuously
[ yes, working on that avenue now, to try something new/ different ]
Now my experience with my 2020 ES300h UL. Software updates fixed a lot of draw but still acts just like yours.
[ assuming nothing we are trying works, we will hand vehicle over to the Lexus dealer for a full week to have them go through everything, and hopefully update any software ]
Most people will not test battery voltage so don't really see the drainage each day. My car driving around 15 miles per day will see battery depleted more each morning down to as low as 11.76v but will still go in ready mode. Drive it and goes back to 12.2 after rest. Even long trips the charging system will never fully charge the battery like an alternator does probably to preserve the HV battery as that is what charges the Aux battery. Once /mth I put a trickle charger on to fully charge the battery but the way this system is designed probably don't have to. No one I have talked to fully understands the aux charging systems in the hybrid just it charges from the HV battery. So long as the parasitic draw is not too high and will give a 2 week ready mode it should be ok but that is also from a fully charged battery and not starting the 2 week point at 12.1v. There should be a switch to completely cut off the DCM module that is causing this excessive drain. A test here for you is to fully charge your battery and test voltage each morning.
[ yes agreed, some days we will let the traction battery with car in 'Ready' mode get up to 12.6v +, and then every day now we test the 12v battery four times a day; yes, fun . . . ]
[[ a switch to turn off the DCM module ? does anyone know where that would be ? ]]
[ Hoping not to have to go the trickle charger route, as I do with my 21 year old pickup truck; seems wrong on multiple levels, but if it has to be . . . ]
Continuing to try to find things to turn "off" and "on". Latest is indeed the 'Connected Services' that Lexus offers - the ones you interact with on the Lexus app. Turned off yesterday, will let rest for 24h and test resting state of 12v battery.
Sitting still with car in "Ready" mode to talk with Lexus support and disconnect the services, the traction battery charges up the 12v to 12.61.
Also, for more info, answering these diagnositic questions from before:
What did they say the ma parasitic draw was?
[ sorry, I didn't think to ask to get that from the service technician; what I was told is after two hours of testing 'at rest', they couldn't find a parasitic draw with their volt meter connected to the 12v battery in series w/ the negative post ]
A full charged battery after 20 minute rest should read 12.7v. How many nights to attain that 11.76v reading?
[ two days essentially; from 12.6 usually down to 11.96 in first 24h cycle, then from 11.96 down to either 11.76v or even 11.43v sometimes next day ]
What kind of driving each day?
[ car is typically used every two to three days, full EV mode for about 20 ~ 30 miles, garage kept, insulated garage in Virginia, mild weather; not cold by any means; typical ambient temp 60 F ]
[[ note on full EV mode: when we drove back from dealer servicing (12v battery change), we drove 100 miles obviously using the ICE only. Running on ICE vs EV has no effect on what the 12v parasitic drain does. ]]
Are both keys far away from car at night
[ ahhh, great joke there my friend, assuming Lexus would provide two key fobs at delivery; only have one right now; have the key 100' + away from vehicle, inside a Faraday RF blocking pouch for anti-theft measure ]
and try disable the digital key in Lexus app as in background may try to communicate continuously
[ yes, working on that avenue now, to try something new/ different ]
Now my experience with my 2020 ES300h UL. Software updates fixed a lot of draw but still acts just like yours.
[ assuming nothing we are trying works, we will hand vehicle over to the Lexus dealer for a full week to have them go through everything, and hopefully update any software ]
Most people will not test battery voltage so don't really see the drainage each day. My car driving around 15 miles per day will see battery depleted more each morning down to as low as 11.76v but will still go in ready mode. Drive it and goes back to 12.2 after rest. Even long trips the charging system will never fully charge the battery like an alternator does probably to preserve the HV battery as that is what charges the Aux battery. Once /mth I put a trickle charger on to fully charge the battery but the way this system is designed probably don't have to. No one I have talked to fully understands the aux charging systems in the hybrid just it charges from the HV battery. So long as the parasitic draw is not too high and will give a 2 week ready mode it should be ok but that is also from a fully charged battery and not starting the 2 week point at 12.1v. There should be a switch to completely cut off the DCM module that is causing this excessive drain. A test here for you is to fully charge your battery and test voltage each morning.
[ yes agreed, some days we will let the traction battery with car in 'Ready' mode get up to 12.6v +, and then every day now we test the 12v battery four times a day; yes, fun . . . ]
[[ a switch to turn off the DCM module ? does anyone know where that would be ? ]]
[ Hoping not to have to go the trickle charger route, as I do with my 21 year old pickup truck; seems wrong on multiple levels, but if it has to be . . . ]
03-28-24, 05:33 AM
#164
HV mode keeps the traction battery charge at about what it was when you placed it in HV mode. Charge Mode actually charges the traction battery to a higher level of charge.
03-28-24, 05:38 AM
#165
For those of us without an actual factory defective battery (that has not died yet) and have measurement apparatus as Dr. Prius or other means of direct battery voltage measurement etc - it might be useful to check the battery voltage droop with a day or two of "Drive Pulse" ON vs. a next day with "Drive Pulse" OFF - while the car is sitting parked and locked in both cases far away from the key fob. The reason being - Drive Pulse definitely sends (at least the) location information periodically to Lexus, and is a potential/likely source of parasitic draw (by potentially "waking up" the car periodically to do its deed). It has to be measured over a day, since the battery power draw would be occasional - and has to be measured over a long enough period to capture any differences. Of course, one would have to remove any aftermarket source of battery draw such as dashcam while doing this measurement, to ensure Drive Pulse is the main parasitic draw factor.
Does that make sense ?
Does that make sense ?