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I'm assuming that they do not allow the traction battery to charge a 12 V is to ensure that if the car is off there's no high voltage going around the vehicle to possibly injure or kill someone.
The 12 volt battery is not charged with high voltage, and there is always high voltage present under the hood and under the car due to the hybrid architecture. Lexus just opted for a simpler/inferior design.
Last edited by PatchManager; Aug 25, 2025 at 12:22 PM.
My 2024 RX350h battery is dead. Dash lights, headlights started blinking. Would not open rear cargo door. Checked my Ionic App to fire up the red battery I installed back in April and I cannot see it:
Am I doing something wrong or is the red battery dead also and is the reason it's not showing? Help!
The Ionic Bluetooth times out after 3 months. Happened to me too. It's the last sentence in the manual before the specs. I wish it was more prominent in the manual. I connect monthly now
The Ionic Bluetooth times out after 3 months. Happened to me too. It's the last sentence in the manual before the specs. I wish it was more prominent in the manual. I connect monthly now
If you do lose the bluetooth connection for the Ionic because of the elapsed time (3 months) you can press the button on the device itself to turn the unit on and it will connect to the app.
I'm following the WellsB approach, have set a monthly 15 minute calendar item to connect from the app. That's infrequent enough to not be a PITA, but often enough that if I do miss one I'll get the reminder the following month (the likelihood of multiple misses by me is low).
Roadside assistance came and used a big portable jumper on the front fusebox and ground metal engine part. Turned car on and in Ready mode without any trouble. Went to the back end and opened my Ionic App and now I could see the battery.
@Markfm so to assure that Bluetooth will still be active besides physically pressing the button on the red battery I can connect from the App and press the start button? And leave on for a while and then press again to stop?
so to assure that Bluetooth will still be active besides physically pressing the button on the red battery I can connect from the App and press the start button? And leave on for a while and then press again to stop?
All you have to do is connect from the app more often than every 3 months. You don't have to press start. I do it monthly just to make sure
My 2024 RX350h battery is dead. Dash lights, headlights started blinking. Would not open rear cargo door. Checked my Ionic App to fire up the red battery I installed back in April and I cannot see it:
Am I doing something wrong or is the red battery dead also and is the reason it's not showing? Help!
Just went to the garage and tried my ionic to see if it was working and had the same screen. I restarted my phone and it came up fine and working.
I restarted my phone and it came up fine and working.
Yes, there is sometimes bluetooth interference with wifi causing this problem (which doesn't have anything to do with the Ionic itself). I keep my 2.4 GHz wifi at home limited to 20 MHz channel width, to prevent interference with Bluetooth (the IoT devices such as home security cameras, etc work fine with 20 MHz wide channels at 2.4 GHz).
However, I did not expect the Ionic to timeout - since the Ionic is really NOT "not being used" for 3 months. Its constantly waking up every time the car is turning on. When I'd read the specs before buying, I understood to mean that if we left it in a closet for 3 months, the bluetooth would timeout. I'm wondering if its a bug we are seeing so I updated to the 1.0.16 FW on my iPhone app. Android could be showing a different latest FW.
Been looking at getting a 25 RX350h but after going thru this thread I've become a bit leery on the idea. It seems most of the issues are with the 450h but quite a few are the 350h. The RX would not be driven every day, probably just 1-3 times a week, and most of the trips would probably be short. Would this be setting me up for a high chance of battery failure?
Been looking at getting a 25 RX350h but after going thru this thread I've become a bit leery on the idea. It seems most of the issues are with the 450h but quite a few are the 350h. The RX would not be driven every day, probably just 1-3 times a week, and most of the trips would probably be short. Would this be setting me up for a high chance of battery failure?
Probably. This time for me there were no trips or week long absence. I drove to the office every weekday (M-F) last week. RX was in the garage Saturday and Sunday. Today it would not start. However, use last week was 7 minute drive to the office and back only. So you would have to drive it more than that, or leave it on for half an hour at home in READY mode at least once a week, or install an Ionic backup battery and pray it works when you need it! It's a great vehicle but today when I was driving my wife's Sienna to the office I really wanted to kick it out of my house, LOL. Now that it's working and that I think I know what to do so that it does not happen again I still want it here.
Curious as to what Lexus changed to cause these battery problems. I don't see any issues with the previous hybrids with the 6 cylinder engines, just the new setup.
Always good to see folks trying to figure things out. I believe it makes sense to try the KISS principle, as it applies to me personally. Why not try the phone restart first, rather than going through the risk of improper jump starting or the gymnastics of manually entering the car to access the battery/ionic. If the restart doesn't work, nothing lost, right? I'll try letting my ionic time out for three months (plus) just for yucks, and try the phone restart to verify or nullify the usefulness after ionic timeout. If no good I'll try activating the ionic before three months to avoid issues.
