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... Just bringing the fob near the vehicle wakes it up enough to drop the voltage about 0.2v.
If that does happen, and by definition you need the fob (or smart card, or phone digital key) to start the vehicle, I'd think it would be valid to have the fob with you when making the measurement.
To me the fundamental question is "will the battery have enough voltage/charge when you try to start the car?"
Do you mean charge mode or HV mode? Holding the HV button puts the vehicle in charge mode, not hold charge mode.
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.
My concern was whether or not the 12v battery was being charged in this mode(ice on charging hybrid battery pack). Now when the car is plugged in at home or wherever, the 12v is not charged or maintained during that process.
If that does happen, and by definition you need the fob (or smart card, or phone digital key) to start the vehicle, I'd think it would be valid to have the fob with you when making the measurement.
To me the fundamental question is "will the battery have enough voltage/charge when you try to start the car?"
Depends on what the purpose is.
If one is wanting to track the speed with which the 12v battery discharges while sitting, undisturbed, then waking up the vehicle each time you take a measurement defeats that purpose.
My concern was whether or not the 12v battery was being charged in this mode(ice on charging hybrid battery pack). Now when the car is plugged in at home or wherever, the 12v is not charged or maintained during that process.
Understood. Some people mistake Charge Mode for Hold Charge mode The button is labeled "Hold Charge" because you have to hold it for a second to put it in Charge Mode.
Hello All, I don't have any experience with the plugin hybrid, as mine is a 2023 350h. But what I can tell you is that based on my experience, those who are experiencing dead battery with 350h, probably are having a batch of bad batteries. Me and my friend bought two 350h premium build in May of 2023 and have not had any dead battery issue since then. He uses his daily. I use mine either once a week or once every two weeks sitting in my garage. I have never seen a low battery message or never had dead battery. My conclusion based on my experience is that there have been a batch of bad batteries built during the pandemic and Lexus is suffering from those bad batches. Also as I mentioned in my previous messages, I have set my settings to keep the radio on till i open the door, i do not keep it in ACC mode, and set to turn off the headlight as soon as I open the door. Just have the Lexus dealer replace the battery. It would be crazy to buy a $70 K car and having to have extra charger in the trunk. Again, just sharing my experience.
It could also be a combination of some marginal batteries combined with a suboptimal charging algorithm. Otherwise, I'd expect to see the same issues in all RXs.
It could also be a combination of some marginal batteries combined with a suboptimal charging algorithm. Otherwise, I'd expect to see the same issues in all RXs.
There's always the power distribution from the battery in the back to the ICE in the front (and any fuse boxes up front) - undersized wiring or routing issues (potential cable pinching kinds of things).
Has anyone that had a battery replaced under warranty run into issues a second time?
I suppose, “stretching it” is any period of inactivity that causes a vendors new battery to go flat. As a frequent traveller, leaving a car at the airport for 2-3 weeks has never left me feeling like I better call the Automobile Association for a boost. I don’t know of any car more electrically demanding than my Tesla, but as far back as 2016 when I got the car, it shuts various systems Down to preserve power.
it’s not rocket science nor would it be a successful marketing strategy to offer a trickle charger as an option for those who “don’t drive their car every day”.
I guess ‘reasonable’ is what ever you want to make it, but let us know how it goes if a cold snap hits and you need a jump! 😉
My 2024 RX450h+ was draining the 12 V battery whenever it sat for a few days. I bought a battery monitor on Amazon that tracks battery voltage and downloads data to the phone. I noticed a cyclical draining of the battery when the vehicle was off. I measured fuse voltages (vehicle off, doors latched) and found the drain was thru fuse ECU-DCC No. 3. I put a fuse extender in and monitored the current thru this fuse. (Fig. Below). Something was evidently turning on and off continuously (vehicle off) and drawing a lot of current. One of the items on this circuit is the Bluetooth Digital Key receiver assembly. (The Digital Key system uses an App on the cell phone to lock/unlock doors and even drive the vehicle without the key fob.) By chance I noticed that the cyclical discharging of the battery was triggered by the garage door opener! (See Fig. Below). It seems the Bluetooth Digital Key receiver was responding to the garage door opener, cycling on and off and discharging the battery. When I disabled the Digital Key system in the car (Settings -> Info & Security -> Enable Digital Keys -> OFF), the problem went away! I’m still able to use the Lexus App to unlock/lock the car, and see info about the vehicle (linking to it through cell phone or WiFI, I guess). But beware the Digital Key—it seems to be a source of serious parasitic battery drain.
Last edited by SMartin; 04-02-24 at 01:41 PM.
Reason: Forgot to mention something.
My 2024 RX450h+ was draining the 12 V battery whenever it sat for a few days. I bought a battery monitor on Amazon that tracks battery voltage and downloads data to the phone. I noticed a cyclical draining of the battery when the vehicle was off. I measured fuse voltages (vehicle off, doors latched) and found the drain was thru fuse ECU-DCC No. 3. I put a fuse extender in and monitored the current thru this fuse. (Fig. Below). Something was evidently turning on and off continuously (vehicle off) and drawing a lot of current. One of the items on this circuit is the Bluetooth Digital Key receiver assembly. (The Digital Key system uses an App on the cell phone to lock/unlock doors and even drive the vehicle without the key fob.) By chance I noticed that the cyclical discharging of the battery was triggered by the garage door opener! (See Fig. Below). It seems the Bluetooth Digital Key receiver was responding to the garage door opener, cycling on and off and discharging the battery. When I disabled the Digital Key system in the car (Settings -> Info & Security -> Enable Digital Keys -> OFF), the problem went away! I’m still able to use the Lexus App to unlock/lock the car, and see info about the vehicle (linking to it through cell phone or WiFI, I guess). But beware the Digital Key—it seems to be a source of serious parasitic battery drain.
Thanks, although I haven't had any battery issues, I'm going to disable the digital key system in the car settings. I have no use for the unreliable digital key.
SMartin....You are one sharp guy and I thank you for this info. Another piece in the puzzle. BUT....in both of our two 450h+ models, neither of us opted to use the digital key, yet the 12v battery in my RX croaked about a week ago. All is well now, after I put a trickle charger on it and I will monitor things a bit more closely in the future but, for me....the mystery continues.
Thanks, although I haven't had any battery issues, I'm going to disable the digital key system in the car settings. I have no use for the unreliable digital key.
03-28-24, 07:30 AM
