12v Battery Incident - Do not use Accessory Mode
03-26-24, 01:01 PM
#16
This is just a PSA for my fellow 350h owners. Waiting for wife while she went into a store to pick us some things, I had the car on "Accessory" mode, engine not running. Only was waiting for about 20 minutes. When she got out, the car would not "start" or enter the ready mode. Many icons showed up intermittently on the dash, the Infotainment screen would start and go off. Crazy antics and no real warning what was wrong. Guessing I depleted the 12v battery I was able to use my "jump start" battery pack to get the car going again. If this had happened without me knowing I was using the battery, you would have no clue what was going on. Too many messages and conflicts. One prominent message was "Parking Brake Not Available". Warning, the rear hatch will not open, the doors will not open electrically but under the hood in the fuse box there is a jump start port.
So, after successfully starting the car (not a lot of power required) I had a ton of messages from "Low Battery Voltage" to "System Malfunction" with instructions to go to the dealer. This being a Saturday afternoon, I took a chance, went to the dealership and the tech could not take the car in but told me the messages would go away eventually once the battery was charged again. He mentioned this could take a day or so. While this message was active, no driver assist functions are available. No cruise control and messages that braking is reduced.
Got home, removed the battery and charged overnight. Re-installed the battery, all the messages were still there. After driving around the area for about 25 minutes and restarting the vehicle all the messages are cleared and all functions back to normal. Apparently removing the battery for charging only resulted in losing the seat memory settings. All other settings and radio settings appear to be fine.
Sorry for the long post, but I could not find anything online regarding low 12v battery conditions and Message Resets. A post like this would have helped me relax and get through this situation. Bottom line, do not use the Accessory mode in your hybrid. Start the car if you will be sitting for a while with the radio on. Hope this helps someone down the road.
UPDATE: Just took a 900 mile road trip with no issues at all. So once the 12v battery is charged again everything goes back to normal. Lost my seat settings and MPG History as far as I know. Everything else is A-OK
So, after successfully starting the car (not a lot of power required) I had a ton of messages from "Low Battery Voltage" to "System Malfunction" with instructions to go to the dealer. This being a Saturday afternoon, I took a chance, went to the dealership and the tech could not take the car in but told me the messages would go away eventually once the battery was charged again. He mentioned this could take a day or so. While this message was active, no driver assist functions are available. No cruise control and messages that braking is reduced.
Got home, removed the battery and charged overnight. Re-installed the battery, all the messages were still there. After driving around the area for about 25 minutes and restarting the vehicle all the messages are cleared and all functions back to normal. Apparently removing the battery for charging only resulted in losing the seat memory settings. All other settings and radio settings appear to be fine.
Sorry for the long post, but I could not find anything online regarding low 12v battery conditions and Message Resets. A post like this would have helped me relax and get through this situation. Bottom line, do not use the Accessory mode in your hybrid. Start the car if you will be sitting for a while with the radio on. Hope this helps someone down the road.
UPDATE: Just took a 900 mile road trip with no issues at all. So once the 12v battery is charged again everything goes back to normal. Lost my seat settings and MPG History as far as I know. Everything else is A-OK
Cheers, DEL92
2023 RX350h Premium+
Eminent White Pearl - Macadamia/Birch
03-26-24, 02:26 PM
#17
If you park your car are and waiting, do this and you will not have dead battery problem (350h): I have not experienced the dead battery issue.
- Set it so the radio stays on till you open the door to go off. (In car setting menu). If you opened the door and the radio goes off, then close the door and just press the radio volume button to turn the radio on again.
- push the start button to turn off the engine so you are not in Ready mode
- If the headlights are staying on, manually turn it off and turn it back to Auto. That way it keeps the lights off.
- Note- if you keep the car in Ready mode, the MG1 is still turning and depleting the battery.
- Also, if you leave the door open , i have noticed that the dome lights goes off after a certain number of minutes (10 minutes or so).
03-26-24, 02:48 PM
#18
More here;
https://youtu.be/O61WihMRdjM?si=JkWQo1HOPq52M51l
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neilsarkar (04-16-24)
03-27-24, 03:56 AM
#20
How does the charging system operate while in Neutral?
Went through a car wash once, in Neutral (as required). Near the end, my 350h gave a low battery warning. When I put it back into gear, the warning went away. That was several months ago, and it's never happened since.
IMHO, the 12v battery is just too small in capacity.
In my last hybrid, a 2014 Infiniti Q50S, I had the 12v battery replaced at 4 years, although it showed no signs of failing. I plan on doing the same with the Lexus. Hopefully, a better unit will be available.
Went through a car wash once, in Neutral (as required). Near the end, my 350h gave a low battery warning. When I put it back into gear, the warning went away. That was several months ago, and it's never happened since.
IMHO, the 12v battery is just too small in capacity.
In my last hybrid, a 2014 Infiniti Q50S, I had the 12v battery replaced at 4 years, although it showed no signs of failing. I plan on doing the same with the Lexus. Hopefully, a better unit will be available.
03-27-24, 03:08 PM
#21
The traction battery does not charge in neutral. The 12v battery still charges. The warning is to prevent you from discharging the traction battery, which would require a wrecker trip to the dealer to rectify.
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wa3cuj (03-28-24)
03-29-24, 06:32 PM
#22
Intermediate
So are you implying by that (as its true for the 350h, which doesn't have plugin traction battery charging), that the warning doesn't exist for the 450h+ because its already protected by the auto-ICE-turn on mechanism if the traction battery reaches 30 % SOC (in addition to being a larger traction battery that probably wouldn't get discharged in a short car wash) ?
03-29-24, 07:00 PM
#23
I've not seen the warning in the 450h+ but I would imagine that it would come if the battery was low enough.
The nature of the hybrid powertrain in the 350h and 450h+ (I dont know about the 500h) is such that the ICE cannot start in neutral. I believe that is the true reason for the warning.
The nature of the hybrid powertrain in the 350h and 450h+ (I dont know about the 500h) is such that the ICE cannot start in neutral. I believe that is the true reason for the warning.
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wrinkle (03-29-24)
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