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I would disagree, in that it is hardly a disaster. It is a bit of an inconvenience at the present time and, it could have been done a bit better by Toyota. I, and many others have found a workaround for the time being. Yes, it requires a bit of monitoring. I had the 12v battery run out of juice once in one of my 450h+ vehicles and have not had a second one since I started letting the car sit in READY mode for 20 to 30 minutes every two to three days. In the center console I installed a volt meter. The voltage jumps from 12.6v to 14.2-14.4v when in READY model, showing that the 12v battery is being charged. Your car should do the same thing and if not, you may want to make a trip to your Lexus dealer. I believe that Toyota will eventually solve this issue with a change in the algorithm and perhaps, a larger capacity battery.
Yeah def an annoyance and problem, and I'll be sure to chime in if something does happen to mine. So far, after almost 3 months, everything is a-ok though, and I love it so far. The ability to go EV for weeks at a time, then switch to HV when we travel far so no worries at all about range or trying to figure out where to charge is freaking amazing
I also have not heard about it in the news, so how widespread the problem is, is not really known.
After suffering from a dead battery and finding that my 9 year old jump starter was only good for a single start attempt, I started looking for a new portable jump starter. The vast majority of portable jump starters have cables that are very short, and I wanted one with cables that would reach across the engine bay. I had almost given up when I found that Schumacher has a line of portable jump starters with much longer cables. I purchased the Schumacher SL1648 from Amazon and have found that it does indeed reach across the engine bay, so that one can connect to the Lexus-recommended jump points.
It is pricey for its capacity, when compared to some other options, but it is very heavily built and feels very sturdy. It comes with a carry bag and charger. I don't know when I'll have need to use it, but Schumacher is a reputable name, so I expect it will work fine.
Schumacher has other options in the same format, from 1000 amps to 2500 amps.
The bad thing about this is that you even have to think about having to do this for a 2024 car. With the hybrid the jump amperage would be real low so a higher gauge negative jump cable could be clamped on as extension. You could even use smaller clamps on made up extension and attach to bolt for ground near the fuse box.
Hi From British Columbia Canada, Picked up my new RX450H+ March 18th (it replaced my 2019 RX 450H) and suffered within a few days the small battery failing - After I got in the car by jump starting I recharged the totally flattened battery with a new 30 amp quality charger - took 2 days to recharge and then tested okay - two days later it was totally dead - I was out of town on a remote island so I decided to purchase at my own expense a 700CCA Optima yellow top battery and removed the lexus 335 CCA battery. Thought everything was fine until after the dealer 1st service the car sat in my garage for 3 days with the small battery going totally dead - jump started and got it back to local dealer who is a good dealer but they don't seem to know how to trouble shoot this issue. I do run on the hybrid battery 100% of the time so I assumed that when I plug in the hybrid charger power it would charge the small battery - dealer too me that lexus only allows a very small charge to the small battery from the plugged in hybrid and not sufficient to charge the battery - they indicate that the small battery only really charges when you are running the gas engine that seems to negate why would you purchase a plug in hybrid. Cannot find any definitive confirmed how does the small battery charge if you are not running your gas engine. Have reached out to Lexus Canada for response on this question,
I think my key fob and the defective lexus app talk to the vehicle resulting in the 12 volt battery being consumed - Totally flattened the original dealer installed Lexus app and reinstalled which fixed the fact that the digital key was not working on the dealer first installed app- I have now put a trickle conditional charger on the small battery and pulled an extension plug from that charger into the rear seat area so I can plug the trickle charger in weekly with the extension cord being fed through the opened rear seat window so I don't have to have the large hatch cover up. I am hoping that Lexus will update the 12 volt charging system with a vehicle update. I often park for 2 - 3 weeks at the airport so I think it will die during that time without the charge, I also purchased a Coco Booster X GRX75 2500 A lithium jump starter that I now keep in the vehicle under my driver seat - it has saved me several times now.
I have appreciated the other postings on the small 12 v battery dead issue as it helped me realize that I am not alone in this Lexus design failing - they are a good company but I hope all of us can get their attention that it needs some lexus fixing so we don't have this issue
Having watched the 12v battery voltage quite a bit, I see no difference in charging behavior with the engine on or off, or between the different modes, as long as the vehicle is in Ready mode.
The cold cranking Amp capacity of the battery is fairly meaningless in this application. The Amp-Hour or Reserve Capacity means much more. Your 700cca Optima likely has the same A-H or Reserve Capacity as the OEM battery, and even a substantially larger capacity battery (that still fits) would probably only give you 25% more time before the battery goes dead.
Ours recently was dead on a Wednesday afternoon, after a weekend where the vehicle was driven in Hybrid Mode for a period of several hours on a Saturday followed by a short EV mode drive on Sunday.
I've since installed a Bluetooth battery monitor so I can easily check it every day.
I'm also planning to purchase one of these, or something like it;
One of its functions is to disconnect the battery before it is completely dead.
matell DC 12V 500A Remote Battery Disconnect Switch Smart Voltage Control Battery Kill Switch for car Anti Theft Battery Shut Off Switch https://a.co/d/grkCQoS
I don't really see the harm in jumping at the battery itself. I have seen these distant posts usage for charging the battery, because of the requirement to charge while including the battery management system. But not for a jump start. Schumacher makes good stuff, I have one of their chargers.
Its crazy that you basically need 3 devices for all contingencies with this. A charger, a battery maintainer/tender for long term connections, and a jump pack for jump starting. I guess you can use the maintainer/tender for charging, but they are slow for that so I have a charger also.
matell DC 12V 500A Remote Battery Disconnect Switch Smart Voltage Control Battery Kill Switch for car Anti Theft Battery Shut Off Switch https://a.co/d/grkCQoS
While preventing against full battery death, would this not also lead to the car losing all its settings/preferences when the relay cut-off happens ? Or are the settings stored in persistent memory/storage - from my readings it seems persistent storage is not the case, since users have reported that new battery changes require ODBII adapter while switching over, to keep the settings ?
I don't really see the harm in jumping at the battery itself. I have seen these distant posts usage for charging the battery, because of the requirement to charge while including the battery management system. But not for a jump start. Schumacher makes good stuff, I have one of their chargers.
I have witnessed two lead-acid battery explosions. I prefer to minimize the chance of a spark near the battery.
While preventing against full battery death, would this not also lead to the car losing all its settings/preferences when the relay cut-off happens ? Or are the settings stored in persistent memory/storage - from my readings it seems persistent storage is not the case, since users have reported that new battery changes require ODBII adapter while switching over, to keep the settings ?
One would see all the same issues that happen with a dead battery. My experience is rhat some preferences are persistent and some are lost with a dead battery.
Just to be clear, my intention is not to use the manual battery disconnect feature, but use the automatic disconnect that kicks in at 20% State of charge.
One would see all the same issues that happen with a dead battery. My experience is rhat some preferences are persistent and some are lost with a dead battery.
Just to be clear, my intention is not to use the manual battery disconnect feature, but use the automatic disconnect that kicks in at 20% State of charge.
Hmm, given some preferences are persistent, I wonder if that has to do with the actual voltage of the battery - in other words, at 8 V - some subsystems have persistent voltage, some less subsystems persistent at 6 V, and none at ~ 0 V. I guess what might happen at the automatic cutoff in the gizmo would be telling, as that would be equivalent to ~0 V for the subsystems.
The interesting thing is - for the OEM Lexus battery in my 450H+ at least - I have measured ~ 11.9 V (i.e. just above ~11.9 V, say 11.93 V) at multiple points with the car operating still and not dead - so it might happen that the automatic cutoff, if happening at 11.9 V as advertised in the example link, might lead to a battery cutoff even though the battery is not fully dead yet... It would be useful to have a customizable cutoff of 11 V or 11.5 V
The first time our battery died, I believe it was in acc mode and the voltage was around 8v when I connected the charger. No settings or preferences were lost. This time, the battery was at about 2.5 volts after sitting for 3 days and some preferences were lost, but most were not.
The battery has degraded a bit more with the last discharge, but still shows 92% of new internal resistance with 70% being considered end of life. Deep discharges like that are playing Russian roulette though and can result in unrecoverable batteries. I feel that 20% state of charge is a good place to disconnect as even that puts a battery in the sulfation zone.
05-11-24, 06:21 PM
. Been thinking of getting one of these for the wife's vehicle. Thanks for the link.
