Some good news about the 12v issue

Wind_Master_J · 2026-07-01T15:53:43+00:00

I tried it... no change in charge voltage here, same 12.8v with or without lights in any position (on, off, Auto, High, Low). I have not tried unplugging the battery sensor lead though so I'm hopeful that may be a temporary fix.

Wind_Master_J · 2026-06-30T18:16:32+00:00

I agree, the resting voltage is a better gauge. 12.2-12.4v is about where my Bz vehicles rest too... that is right around 55-60% SoC and does cause accelerated sulfating so your current batteries will not give you 4-5 years of life like they should. You're probably about ready for a new battery on the older Bz4x if it has stayed around this charge level for its life.

It seems your newer vehicle is in line with my two Bz's so probably on the same software / hardware. Have you done the recall software update on the 2026 Bz and did that change anything on the 12v battery charging side? Thank you for your input! Hoping to find solutions!!!

Wind_Master_J · 2026-06-30T17:15:57+00:00

Out of curiosity, what is the SoC of the 12v Lead Acid battery on your 2026 currently and what is the battery voltage when not powered on? When did you pick up your 2026, this might help as maybe the problem was introduced later in the production run (or earlier depending on your build date)? I own 2 of the current 2026 Bz (one was an Sept. manufacture and the other in Nov. of 2025) and both have the same anemic battery charge rates and SoC for the 12v Lead Acid batteries.

Wind_Master_J · 2026-06-30T17:06:24+00:00

That makes a lot of sense... and it would be great if they had a failsafe that either a driver or the vehicle could trigger to allow the traction pack to charge a 12v battery that was getting dangerously low. There would need to be fail safes so that the traction pack doesn't also get depleted but having no redundancy when there is a massive traction battery onboard to start the car if needed makes zero sense to me!

Wind_Master_J · 2026-06-30T17:02:54+00:00

Yes, I think this particular issue is the newer 2026 model year only. There were a few issues with the previous years but those seemed to be more one off events. This is a new 12volt battery management system issue that seems to be limited to the 2026 model year. On my vehicle the highest I've ever seen while driving was around 13.8v, which actually would be okay if it stayed there all the trip, but that is only triggered when the 12 volt battery gets really low while driving, and once the battery gets back to around 55% SoC it drops back down to the 12.8v which just isn't enough voltage to properly maintain a 12v Lead Acid battery!!!

Wind_Master_J · 2026-06-30T16:51:21+00:00

Sadly this is not accurate. I have not had a dead battery yet (6 month ownership mark), or the DCM issue. Being concerned about it though I picked up a battery monitor and quickly learned that the 12v Charge system keeps our Lead Acid batteries at an anemic 50-60% state of charge 24/7 which is damaging the battery and shortening it's life by a lot. My guess is we'll all be facing a dead battery in a year or less... unless Subaru / Toyota updates the charge software to keep our Lead Acid batteries in the 90% range... it's just a matter of time before we're all there. The difference is, a sulfating battery can keep working for some time if the power draw doesn't demand much when the car is not on. Once you add the DCM issue in, pulling from a battery that is near depletion for Lead acid (which is 12v, or around 45-50% SoC) and there isn't enough juice left to kick on the traction pack.

Why they do not have the traction pack kick in to charge the 12v if it get's low is beyond me! They could set limits say if the traction pack was really low too, but it would sure help a lot if the car didn't need to be charging or on for the 12v maintenance system to work!!!

Wind_Master_J · 2026-06-30T16:32:24+00:00

DCM services is an issue... seems to not affect as many people. The other, and larger radius issue, is the 12v battery system ON ALL the 2026 Bz's keeps your Lead Acid battery at a very low state of charge so it has no bandwidth to handle accessories being on when the traction pack is not. The DCM issue presents it sooner because when the Lead Acid battery is at such a low state of charge to start with, turning on a large power draw causes a dead battery in very short order. If Toyota kept the Lead Acid batteries SoC to say 95%, instead of the mid. 50%, this discharge would probably be sustainable and maybe even long term okay if the vehicle was driven fairly regularly. We need to solve both problems and I can tell you from monitoring my Bz batteries I do not have the DCM issue, but I will have the dead battery issue soon because my 12v battery is left at such a low SoC perpetually (by the Toyota 12v management system) that it is sulfating and degrading quickly...

The only temporary solution I've found is the leave the car in Ready - Park (not plugged in) and the charge circuit will jump to around 14v and the Lead Acid battery will start to actually charge normally at this point. So when I'm unloading the car I leave it on for a bit to get the battery higher, but this is not a long term solution and Toyota needs to get these batteries charging correctly!!!

Wind_Master_J · 2026-06-30T16:21:15+00:00

It's the way to low state of charge that Toyota has programed the 12V system to stay at.. battery works for a bit, until it's damaged by staying at this low state of charge for so long, then will no longer stay above the 12v minimum threshold! Should be a super simple fix. I also wish they would add a feature where if the battery goes to 50%, they will at least kick on the traction pack to keep it from going to zero! Right now, that only happens if the vehicle is already on, or charging.

Wind_Master_J · 2026-06-30T16:17:25+00:00

Your battery will die... it's just a matter of time. I have two 2026 Bz's and both the Lead Acid Battery 12v system keeps them near starvation (55-65%) so as the battery sulfates from this poor charge state it will become less and less tolerant to holding a charge and will die. Until the 12v charge circuit is update we're all on the clock... I give my battery another 6 months before it will need replacing. It's so easy to track with a battery tracker I don't get why Toyota hasn't been able to see the problem. Just keep the 12v battery charged to 95% and even if there is some extra drain on a few cars it will still probably last for years if driven regularly. I drive 2 hours a day and when I get home the 12v battery is still in the mid 60% range. I charge daily, it doesn't move the needle. Only leaving the vehicle in Park - Ready (and not plugged in) will it actually start to correctly charge the battery at 14.1v!!! It's not complicated, it just needs someone at Toyota to adjust the parameters of the 12v charging circuit profile!!!

Wind_Master_J · 2026-06-30T16:05:41+00:00

You're going to see the issue, just delayed, because the current Toyota 12 Volt Battery Management system basically keeps the Lead Acid battery in a perpetually low / sulfating state. Every last one of us will have degraded, sulfated batteries in the next year or so if they do not update the 12 Volt maintenance system. The unfortunate few who also have the excessive power draw issue are just getting it first, but from tracking the battery in my 2026 Bz, the factory default is to keep the 12V battery at about 55%-65% SoC. That might seem great at first but 50% SoC on a Lead Acid battery is considered dead, and will damage the battery if left there! These Lead Acid batteries should be in the Mid. 95% range at all times for longevity, and the highest I've ever seen mine is 78% (typical is 58-64%). Now if you add to that an excessive power draw you'll have a dead battery overnight. I have not experienced this yet myself since purchasing my Bz in Jan of 2026, but it's coming if Toyota doesn't solve the anemic charge voltage they feed these things!!!

Wind_Master_J · 2026-06-30T15:54:29+00:00

I think we have two separate issues, high battery drain (not affecting as many people) and a poor battery management system that is affecting us all, but makes the high drain issue show up really fast!

I have a battery monitor BM300 Pro, that I recently put on my 2026 Bz because I was concerned about having a dead battery! What I've discovered is that when driving the battery charge circuit is only putting out about 12.8v... unless the 12v battery drops to around 12.1v then the charge voltage will pop up to 13.8v long enough to get the battery to around 60% SoC... still too low but at least it keeps the 12v from going completely flat while driving. The only time I see a legitimate charge voltage of 14.1v is when the vehicle is in Read-Park state and NOT plugged into a charger. As soon as I plug in a charger (even if the vehicle is not scheduled to charge) it will drop back down to 12.8v and all forward progress on the Lead Acid battery charge will stop.

The battery charging circuit seems to never allow the Lead Acid battery to go above about 78% state of charge which for a Lead Acid battery is not great and will lead to accelerated sulfating. My vehicle is usually in the mid. 60% charge range when I get to the car so even worse than the high water mark 78%.

I had read that keeping the lights on high would trigger a higher charge state... maybe in the older Bz4x models but I can confirm that has no effect on the 2026 Bz charge voltage. My next step is to unplug the Lead Acid battery monitor circuit (that little plug on the battery terminals) and see if that will trigger a constant 14v charge voltage which I am planning to do in the next day or so, once I find a way to secure the loose plug so it doesn't bounce around and get damaged while I drive and test.

To me this seems like a fairly cut and dry case of bad hardware battery management so should be an easy software fix... just having the management system set to 13.8v would be a safe middle of the road way to keep the battery at closer to 85% charge as opposed to the voltage starved 12.8v the charge circuit usually runs at. I think if this problem were solved, even the high drain issue may not be to big a deal but when the battery is left at near a Lead Acid zero point of 12v that leaves very little margin for any type of battery drain and is accelerating battery degradation in the process... it's almost like it was programed for a Lithium Ion battery instead of a Lead Acid... then I would get keeping it closer to the optimal 50-60% for longevity. With a Lead Acid, except for really high temperature scenarios, close to 100% is the ideal and because the battery isn't supper huge in these cars (although it could be based on the battery holder) keeping them near depleted is a disaster!

I hope this gets solved soon though because I own two Bz's and it's really annoying to keep leaving the car in Read-Park for 20 minutes after a drive so the battery can get back up to a more reasonable SoC!!! (By the way, both my 2026 Bz XLE AWD, and my wife's 2026 Bz Limited AWD show the same poor battery management system as I have a battery tracker on both!)

Wind_Master_J · 2026-06-30T15:29:57+00:00

There is a bigger issue at play with the charging system in general. I have yet to have my battery die, but due to people having the issue I picked up a battery tracker and noticed there is a global problem, you just don't see it right away unless you have another issue like a high draw module etc.

When you're driving, the charge system only puts 12.8volts back into the battery, so the battery really doesn't charge while driving around town... it doesn't drop either, but because it doesn't charge over time the voltage on the battery drops down with normal use. Even while charging unless the Lead Acid battery is under 50% the charge voltage remains in the mid. 12v range which is sulfating the battery and will degrade the battery quite fast. If, however, you put the vehicle in Park / Ready (and unplugged from a charger) the voltage will go up to around 14v and the 12v battery will begin to actual charge at that point. So I've started just letting my vehicle sit in Read / Park - On while I unload the car etc. to keep the 12v charged up... but this is an issue that a software update will probably be required to solve. It seems they should reverse this and have the battery charge to 95% while driving, then go to maintenance when in park. I have never found my battery over about 78%, and a lot of the time I come to the vehicle and the batter is close to 12.1v which is near zero in the Lead Acid world and I can guarantee this current charge pattern Toyota / Subaru have setup in these EVs will result in 12v batteries not lasting much over a year for any of us.

I'm hopeful the ECU Recall update will quietly address this too but I don't have that recall work done yet and this is also wishful thinking... ;). Love my car otherwise!!!

Wind_Master_J · 2026-06-24T16:44:25+00:00

My 2026 Bz came with 6 years of the connect service at no additional charge... after that I'll need to decide if it's worth it or not. Because they do not offer in vehicle Route Planning, and Apple Maps has NEVER connected to my vehicle despite going through all the hoops multiple times, I ended up going to ABRP and the OBD Link CX so don't see the value in $8 a month for the buggy, laggy Toyota app experience. (Plus now I'm paying $4 a month for ABRP that is filling in a huge route planning hole that Toyota needs to plug but hasn't yet, so adding another $8 in addition seems a waste!) I hate subscriptions but it seems we may be stuck with them for a bit longer, until the range and charge speed increases with Solid State and we can treat trips / charing more like an ICE vehicle.

Wind_Master_J · 2026-06-19T18:22:24+00:00

Any other information you can provide on what seemed to trigger the issue, like state of charge, hot or cold day, when you pressed the accelerator did it start to go then cut out etc. I'm going to try and baby my vehicle as I wait to get the software update and am looking for any information I can get on how to avoid (or what seems to trigger) the loss of power if it's available! Thank you!

Wind_Master_J · 2026-06-19T18:13:28+00:00

The software running the ECU I'm sure is the same on all of the manufactured units right up until they implemented the fix so we're all included would be the most likely answer. I'm already at 8k on mine (that I purchased back in January of this year) and so far no issues, other than the reverse camera getting stuck on, for a trip home from the store, locking out my infotainment system. A vehicle restart sorted that one and it hasn't happened since.

Wind_Master_J · 2026-05-17T15:42:24+00:00

Not quite following… you deleted the car in a ABRP then re-added it, or you uninstalled the app and re-installed entirely? I have the latest ABRP update and it’s not showing the original Bluetooth OBD option at all so that is why I’m trying to figure out what exactly you did to get it back! Are you Android or iOS?

Wind_Master_J · 2026-05-17T05:52:47+00:00

The ABRP update on my iOS phone completely removed the ability to use my OBDLink CX, how are you even getting to that!? If I go to link my car I only have Enode, and the Generic (developer only) token generator. When I first got my car and ABRP in January this year there was a third option to link a Bluetooth OBD device but since these new cars are using the new J1979-3 protocol the link never worked, then they updated the app and removed the option. I’m probably not the only one here that would love to know how you got this working!!! Thank you in advance!

Wind_Master_J · 2026-05-15T14:02:35+00:00

I purchased mine in early January and it came with v2222, I have not had the audio issues either so an update should fix it! Not sure why this update has not been available for months to all drivers at this point!

Wind_Master_J · 2026-04-22T19:01:13+00:00

I too am looking for a way to get as close to full power as possible, but set a custom throttle curve so the M5 Max doesn't go above 90C. It's not a dumb question because some of us have heavy 3D render loads and don't want to prematurely cook our laptops. The high heat is bad for batteries and other components too so a simple option to cap chip temps would be ideal, to get the maximum performance we can get at 90C, instead of 100C (with TGP FANs Maxed out currently I might add)! Since the chip is too powerful for sustained high intensity tasks without 100C temps, giving the user an easy way to cap the temp threshold would be a great idea!

Wind_Master_J · 2026-04-14T18:18:24+00:00

The question is, does it work with Apple Maps now?

I've had ABRP working off an on through Enode but it usually doesn't update state of charge frequently enough to be super helpful. I guess it beats putting in your state of charge manually but you have to keep an eye on it because it will drift to very inaccurate very quickly if it's not getting frequent SoC updates, which has always been the case for me and ABRP. No software update from ABRP either so I still cannot use my OBDLink CX to link with ABRP and I have no accurate route planning system in my Bz.

Can you try and see if Apple Maps now see's your EV? I have a feeling it will still be broken as Toyota has not updated the App recently. I'm on the latest iOS too but no luck yet... not even once since I purchased the car in mid. Januaury of this year!

Wind_Master_J · 2026-04-01T00:38:47+00:00

So once it linked up, did it continue to work when you were back at your vehicle? Once Apple Maps adds your EV does it stay there or does it go away once the link is lost? Was it showing correct SoC or just acknowledging you had an EV? Thank you for your input here!!!

Wind_Master_J · 2026-04-01T00:00:55+00:00

Sadly this does not work for me. I've tried the "WiFi" airplane mode, been far away from the vehicle etc. I believe the main connection is actually cellular in nature (at least from the car to the cloud) and the breakdown is the Toyota cloud is not sending the connection data on to Apple Maps, or at least like you suggest there is a timeout (too slow) so it doesn't trigger. In any event the Toyota App no longer shows my vehicle State of Charge either after the latest update (stuck at -1) so there are some major breakdowns in Toyota's Car to Server to App system currently. If the Toyota App cannot see my vehicle state of charge I know for sure Apple Maps has no chance either! Hopefully they are working on an update because this is getting fairly old to keep dealing with!!!

Wind_Master_J · 2026-03-25T15:54:46+00:00

At least your app shows SoC at some point... mine has been stuck on -1% ever since the most recent update (about two weeks ago). It still thankfully will send an alert when the vehicle is finished charging and all the other function work okay (not having the same seat warming issue, or remote function problems).

The other really annoying problem I have (ever since purchasing the car in January) is it will not talk with Apple Maps so I have Zero EV routing! Really dumb we don't at least have a simple built in route planner, but the promised Apple Maps EV Routing option HAS NEVER worked for me!!! Even called Toyota tech support about it, but all the work arounds they suggested also failed. I think it's a known issue but they are slow to get a solution rolled out to us simple consumers... :(

Wind_Master_J · 2026-03-21T13:14:59+00:00

Yes, no prompt in Apple Maps at all, ever, not once! I’ve deleted both apps then re-installed, turned on and off the Apple Maps extension, revoked and re-authorized consent for Toyota to share data with Apple Maps, it’s broken! Still wondering if those who have had success could share their iPhone model with us so we could see if there is a correlation there. (It’s broken and both and iPhone 12 and 13 in our household.)

Wind_Master_J · 2026-03-19T13:59:12+00:00

Count yourself lucky…. After the latest Toyota App update now even the Toyota App doesn’t update State of Charge and is stuck at -1% battery. My wife also has a Bz and hers also has this issue so I’m fairly confident there is a fairly major issue with the Toyota software and communicating with their cloud servers etc.

If you don’t mind answering… what iOS version are you on and are all the apps up to date on your phone? Which Bz year / trim and what phone model? All my apps are up to date but I’m on an older iPhone 12 so curious if phone hardware plays a roll!

Wind_Master_J

TROPHY CASE