Dead 12v battery Incident (merged threads)
06-03-24, 08:02 AM
#376
10th Gear
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2024 rx450h+
My 12v battery failed .. fatally ... after about 900 miles - using the car solely as an electric vehicle - recharging when necessary - towed to dealer and a battery replacement was completed.
That simplifies a complex - frustrating and time consuming series of events. ;I HAVE DETERMINED THAT THE 12V SYSTEM IS NOT PROPERLY CHARGED WITH THAT TYPE OF USE FOR THE CAR AND HAVE OBTAINED A CHARGING SYSTEM FOR THE 12V WHICH I USE FOLLOWING EACH CHARGE OF THE MAIN DRIVING BATTERY.
That simplifies a complex - frustrating and time consuming series of events. ;I HAVE DETERMINED THAT THE 12V SYSTEM IS NOT PROPERLY CHARGED WITH THAT TYPE OF USE FOR THE CAR AND HAVE OBTAINED A CHARGING SYSTEM FOR THE 12V WHICH I USE FOLLOWING EACH CHARGE OF THE MAIN DRIVING BATTERY.
06-03-24, 08:22 AM
#377
Interesting TSB for predelivery maintenance on hybrids and BEVs from Lexus: https://static.nhtsa.gov/odi/tsbs/20...44125-9999.pdf
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wrinkle (06-03-24)
06-03-24, 08:39 AM
#378
One interesting thing I've found is that the only time the charging system truly charges the 12v battery is when the vehicle is in Ready mode and in park. That is the only time the charging system continously outputs over 14 volts. It also does that, after a few minutes, in remote start mode.
When plugged into the EV charger, the voltage is around 12.65v. In normal driving, regardless of the mode, the charging system is usually around 12.8v.
When plugged into the EV charger, the voltage is around 12.65v. In normal driving, regardless of the mode, the charging system is usually around 12.8v.
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StefanoS (06-03-24)
06-03-24, 09:18 AM
#379
I've been watching our 12v battery via a Bluetooth monitor quite a bit since May 16th. Nothing conclusive yet, but I've seen 12v battery discharge behavior that seems to be related to the key fobs being too close and a Wi-Fi/ Bluetooth enabled EVSE that seemed to be waking up the vehicle constantly. With the key fobs about 30' away and no EVSE waking it up, I've seen days with very gradual discharge, to where it could go a week between starts, but still a deeper discharge than I like.
I've also seen discharge behavior that I cant explain, though I think it may be due to WiFi and or Bluetooth devices of unknown origin, probably from neighbors, though it's random. I check both battery monitors on my cell phone and the SOC drop dramatically overnight.
Another worrisome behavior is that the 12v charging system makes no attempt to fully charge the battery, with the end result being a "normal" resting voltage of 12.1 to 12.4 volts, which means that the battery cannot provide near its rated capacity, explaining why it dies so quickly in ACC mode, and is also in the range where sulfation occurs, which will greatly reduce battery lifespan.
I've now taken to fully charging the battery with a charger every week, rather than every month.
I've also seen discharge behavior that I cant explain, though I think it may be due to WiFi and or Bluetooth devices of unknown origin, probably from neighbors, though it's random. I check both battery monitors on my cell phone and the SOC drop dramatically overnight.
Another worrisome behavior is that the 12v charging system makes no attempt to fully charge the battery, with the end result being a "normal" resting voltage of 12.1 to 12.4 volts, which means that the battery cannot provide near its rated capacity, explaining why it dies so quickly in ACC mode, and is also in the range where sulfation occurs, which will greatly reduce battery lifespan.
I've now taken to fully charging the battery with a charger every week, rather than every month.
Last edited by StefanoS; 06-03-24 at 11:39 AM.
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WellsB (06-03-24)
06-03-24, 10:40 AM
#380
Instructor
What is strange is that Lexus is not acknowledging what is the normal parasitic drain so you can check and see if in parameters. It takes a lot more power to transmit than receive and I feel the DCM is the main problem. The computers will as always be parasitic drain but it will be constant and a known draw. With all the services that contact the car (receive) the car responds (transmits) and that is the variable. I did find with my 2020 ES300hUL that after the services expired I don't see my battery below 12 volts anymore after a few days. As others mentioned the charging system for the Aux never fully charges the battery and probably to maximize mpg.
06-03-24, 11:45 AM
#381
I've now taken to fully charging the battery with a charger every week, rather than every month.
06-03-24, 02:17 PM
#382
So far as I can tell, a normal draw-down is about. 0.1v per 24 hours from 12.7v until it gets to about 12.2v when the draw-down seems to slow dramatically.
I've also seen it go from 12.6v to 12.1v in 3 hours from something continously waking up the vehicle.
I've also seen it go from 12.6v to 12.1v in 3 hours from something continously waking up the vehicle.
06-03-24, 03:06 PM
#383
Instructor
The decrease in voltage is also highly dependent on the condition of the battery as the same current draw will deplete each battery different.
06-03-24, 03:20 PM
#384
06-03-24, 07:34 PM
#386
2nd gear
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Your battery was dead at the first try. The mods will move your post to this thread on dead 12V batteries: https://www.clublexus.com/forums/hyb...-incident.html
Need to use trickle charger whenever I plug in the traction battery. Seems like a not well thought out design.
06-03-24, 07:49 PM
#387
You are correct. I jump started it and it ran after that. The problem seems to be that when running on EV ode the 12 volt battery doesn't get recharged adequately.
Need to use trickle charger whenever I plug in the traction battery. Seems like a not well thought out design.
Need to use trickle charger whenever I plug in the traction battery. Seems like a not well thought out design.
EV mode is actually better than HV mode because the 12v battery is trickle-charged while the traction battery is being charged, but it's still not enough.
06-04-24, 03:07 PM
#388
Dealer suspects DCM
Dealer has informed me they opened a case with the factory and suspect the DCM. Asked me which remote functions I'm using the app for, who is my carrier, and have I added or deleted any users or changed my account using the app. In my case, I only use the app to lock the doors during charging (mainly to shut up the notifications from the Lexus app on my phone that the car is unlocked), carrier is Verizon, and no changes made to account. Expecting more info from them soon.
For those of you using a BT battery monitor, how did you go about connecting it since no access to battery terminals?
// RX 450h+ purchased 5 weeks ago
For those of you using a BT battery monitor, how did you go about connecting it since no access to battery terminals?
// RX 450h+ purchased 5 weeks ago
06-04-24, 03:22 PM
#389
The battery is under the rear cargo area, under a pop-off plastic panel. It's easy to get to.
06-04-24, 04:02 PM
#390
Dealer has informed me they opened a case with the factory and suspect the DCM. Asked me which remote functions I'm using the app for, who is my carrier, and have I added or deleted any users or changed my account using the app. In my case, I only use the app to lock the doors during charging (mainly to shut up the notifications from the Lexus app on my phone that the car is unlocked), carrier is Verizon, and no changes made to account. Expecting more info from them soon.
For those of you using a BT battery monitor, how did you go about connecting it since no access to battery terminals?
// RX 450h+ purchased 5 weeks ago
For those of you using a BT battery monitor, how did you go about connecting it since no access to battery terminals?
// RX 450h+ purchased 5 weeks ago
