12V battery problem

[Mike100C]

Hi all, I have posted on this subject above, but just to add, the Battery problem, in my situation, is pretty much exclusively because I don't drive my car regulalrly enough. If your vehicle is your "daily driver" and cover a reasonable daily journey, say 30 - 40 miles, the chances are that you won't experience Battery issues. Mine started (Previous Car 2021 NX 300h) during the colder months and I was almost daily getting warning messages on the Lexus link app telling me to keep an eye on my Battery and that Battery level was now critical. I was unaware that the 12volt Battery was discharging due to lack of use, this almost leading to a totally dead Battery over the Christmas period - even less driving. The above posts explain how the charging works, no alternator etc... After much searching I found a solution, which was to add a direct connection to the 12v Battery which in turn would connect to a trickle charger when the car was parked up. The messages soon stopped and all was well. I now have the NX450h+ and have added the same connections to my 12 volt Battery and leave the trickle charger on when the car is not in use- so far so  good and don't expect to get any Battery notifications - now using the Lexus link + app. I still carry my jump starter (belt and braces). As I've said before this is not a problem exclusive to Lexus and is common with PHEV and EV's. Personally I think that this important information should be made clear before purchasing either by the dealer or Manufacturer and offer a trickle charger kit (fitted) as an option, or better still charge the 12 volt Battery alongside the main batteries when plugged in! An interesting topic nonetheless.

[ColinBarber]

13 hours ago, Harrier Man said:

I share the understanding of the system as described by Colin and the doctor but why is it then that several people have had problems with the battery? It seems hard to identify the true cause of the drain. Can the battery really be drained so much by having the doors open during valeting or from having a dashcam live when the car is parked or from having the alarm triggered? Shouldnt there be some protection to prevent the battery from draining below a critical level? I can't believe there isn't. Some have had batteries replaced but quality assurance is pretty good these days so the number of genuinely faulty batteries seems high to me. Are they being replaced just because it's an easy thing to do?

I doubt there was anything wrong with batteries replaced under warranty other than they had been deeply discharged and damaged that way - which is technically abusing the Battery and really shouldn't have been replaced under warranty - although almost impossible to prove one way or the other and as you say are probably being replaced because it is easy and shows some good will.

Most posts in this thread are for issues where people have been using accessory / ignition mode rather than Ready mode when sitting in the vehicle. This will drain the Battery very quickly, it is small and the vehicle's electronics, heating/fans, side lights, audio system etc. do take a lot of power. There are at least 10 warning throughout the user manual for this:

 

Auto power off function

• ●  If the vehicle is left in ACC or ON (the hybrid system is not operating) for more than

  20 minutes with the shift position in P, the power switch will automatically turn to OFF.

• ●  If the 12-volt Battery is low with the shift position is in P and the power switch is in ACC or ON (the hybrid system is not operating). The power switch is automatically turn to OFF.

  However, this function cannot entirely prevent the 12-volt Battery discharge. Do not leave the vehicle with the power switch in ACC or ON for long periods of time when the hybrid system is not operating.

 

 

To prevent 12-volt Battery discharge, ensure that the hybrid system is operating while setting up the display features.

 

 

To prevent 12-volt Battery discharge
Do not use the functions when the hybrid system is off.

 

 

To prevent 12-volt Battery discharge
Do not use the functions when the hybrid system is off.

 

 

To prevent 12-volt Battery discharge
Do not leave the lights on longer than necessary when the hybrid system is off.

 

 

To prevent 12-volt Battery discharge

Do not use the USB charging ports for a long period of time with the hybrid system stopped.

 

 

To prevent 12-volt Battery discharge

Do not use the power outlets (12 VDC) for a long period of time with the hybrid system stopped.

 

 

To prevent 12-volt Battery discharge

When the hybrid system is stopped, do not use the wireless charger for longer than necessary.

 

 

To prevent 12-volt Battery discharge, ensure that the hybrid system is operating while setting up the display features.

 

 

To prevent 12-volt Battery discharge, ensure that the hybrid system is operating while the changing the settings of the head-up display.

 

 

To prevent 12-volt Battery discharge

• ●  Turn off the headlights and the audio system while the hybrid system is off.

• ●  Turn off any unnecessary electrical components when the vehicle is running at a low speed for an extended period, such as in heavy traffic.

 

 

Charging the 12-volt Battery

The electricity stored in the 12-volt Battery will discharge gradually even when the vehicle is not in use, due to natural discharge and the draining effects of certain electrical appliances.

If the vehicle is left for a long time, the 12-volt Battery may discharge, and the hybrid system may be unable to start.

(The 12-volt Battery recharges automatically while the hybrid system is operating.)

 

 

[RONNIE W HODGEKINSON]

On 9/30/2023 at 9:14 AM, David Williamson said:

Good morning, I have a NX450 h+ delivered in April and has 5500 miles on the clock. Yesterday whilst sat in the vehicle, waiting for my wife to come back from shopping, I had the DAB radio on listening to the Ryder Cup. After about 30 mins the 12v battery went flat, cut the power and locked me in the car! I was in a covered car park so the headlights were on Auto.
 

I called for AA assistance who came with 40 mins and discovered the battery was down to 7v. He got me restarted and we were able to proceed on our journey. Anyone else experienced problems with the 12v battery? Thanks

Get Yourself a NOCO GB 40 Battery booster iDEAL FOR THIS VERY SITUATION.. Carry it in the car always... So Easy To Use..

[bgb]

Aagh, happened to me this morning.  I was only in the car because I was sorting the dreaded profile error for the wife before she set off for a 250 mile road trip.  Can only have been 5 mins.  No jump leads so had to wait for the AA. Wife not happy as 1.5 hrs late setting off!  So many little things spoiling the experience of this car.

[Hayzee]

1 hour ago, bgb said:

Aagh, happened to me this morning.  I was only in the car because I was sorting the dreaded profile error for the wife before she set off for a 250 mile road trip.  Can only have been 5 mins.  No jump leads so had to wait for the AA. Wife not happy as 1.5 hrs late setting off!  So many little things spoiling the experience of this car.

Has the car not been used very much recently Jon?

[NemesisUK]

1 hour ago, bgb said:

Aagh, happened to me this morning.  I was only in the car because I was sorting the dreaded profile error for the wife before she set off for a 250 mile road trip.  Can only have been 5 mins.  No jump leads so had to wait for the AA. Wife not happy as 1.5 hrs late setting off!  So many little things spoiling the experience of this car.

Did you have the car in the Ready state?

[bgb]

4 hours ago, Hayzee said:

Has the car not been used very much recently Jon?

Constantly in use, just a combination of me being stupid (i've read all the posts in this thread!) and the circumstances of quickly trying to fix something before the road trip (obviously I'm blaming the profile error for this!!)

[bgb]

4 hours ago, NemesisUK said:

Did you have the car in the Ready state?

Nope, hopefully won't make that mistake again, was literally 5mins tho....

[Husky125]

Two weeks ago I would have only glanced at this post but after being stuck for nearly fours hours with a flat Battery it's not funny. Went to a motorcycle event and left car unlocked so the others could get in, but ignition off and no radio on. Can only assume the opening and closing doors drained Battery and when I tried to start, seat went forward but no ready light. Thinking it was just playing tricks got out locked and tried again, lights then flashed, alarms beeping but no start. Called Lexus assist and given an 70 minute wait, this increased every 15 minutes, then went to 4 hours after the first call. Someone came from home with jump leads and started it ourselves. Car in for a check, but they told me it will only give a flat Battery code, no faults will show up.

Lexus customer service reply to my email is that they use the AA and have no control over there call outs !

A few things to be learnt 

The car default is to lock all doors when Battery flat, so keep one open.

Open bonnet at once so you can get to the jump start connections.

Keep a power pack with you at all times.

This is my first Lexus and really enjoy the car, but at times find it bewildering, I have had a sponge on fuel flap to keep it open, stood holding door handle trying to get in on cold days and now the Battery !

Lastly I find it most upsetting that faults that you high light to Lexus Customer service are ignored, both the fuel flap and door handles I have had to request with my dealer after seeing solutions on here.

 

 

 

 

[DBIZO]

3 hours ago, Husky125 said:

Two weeks ago I would have only glanced at this post but after being stuck for nearly fours hours with a flat battery it's not funny. Went to a motorcycle event and left car unlocked so the others could get in, but ignition off and no radio on. Can only assume the opening and closing doors drained battery and when I tried to start, seat went forward but no ready light. Thinking it was just playing tricks got out locked and tried again, lights then flashed, alarms beeping but no start. Called Lexus assist and given an 70 minute wait, this increased every 15 minutes, then went to 4 hours after the first call. Someone came from home with jump leads and started it ourselves. Car in for a check, but they told me it will only give a flat battery code, no faults will show up.

Lexus customer service reply to my email is that they use the AA and have no control over there call outs !

A few things to be learnt 

The car default is to lock all doors when battery flat, so keep one open.

Open bonnet at once so you can get to the jump start connections.

Keep a power pack with you at all times.

This is my first Lexus and really enjoy the car, but at times find it bewildering, I have had a sponge on fuel flap to keep it open, stood holding door handle trying to get in on cold days and now the battery !

Lastly I find it most upsetting that faults that you high light to Lexus Customer service are ignored, both the fuel flap and door handles I have had to request with my dealer after seeing solutions on here.

 

 

 

 

Others will tell you the same: the Achilles heel of hybrid Lexus (and Toyota) cars is the small starter Battery. Like many of us, I too learned the hard way. Consider yourself lucky, because it happened to us at Stansted airport, after coming back, cold rainy night, and similar 4-5 hours of wait for AA who almost gave up because couldn't start the car at all then suddenly and miraculously started the computer and the hybrid system. It was clearly just a 12V Battery in poor condition the Lexus dealer should have swapped out before selling it after months on the forecourt, but clearly either they don't have that in the protocol or ignored it.

Because your car is new and what you described doesn't read like something that would drain the car, something is amiss. Also, from my experience, the car protects itself as much it can from draining the 12V rather than the much bigger traction by shutting itself down. At least my 2015 IS300h switches off from Accessory mode after a while. Also, it switches of internal lights etc after a period of inactivity. So I wonder what load could have that been...what opening the door does to a switched off car? It turns the internal lights on, that's all. That can't be it, can it. There must be a system in the car that was left on...

Is there a chance you left the car unused for a couple of weeks before? Deep discharge damages lead-acid batteries, they prefer being kept nearly full at all times. If I were you, at this point I would get a new 12V Battery for peace of mind and have it replaced by a garage that knows Toyota/Lexus hybrids. A simple Battery swap can upset downstream electronics, many people report issues with the amplifier afterwards.

Re Lexus service, mostly good experience, but it's a rich mix on these forums. Personally, I'm leaving the Lexus network behind (including Lexus branded insurance) because I lost my trust that the name guarantees premium service. Sometimes you get the premium services, sometimes it's a headache, sometimes you are just ignored. That's not good enough. I admit I have a very low tolerance for things not going smoothly, particularly when the thing costs me dearly, like a service plan.

[Husky125]

Car used most days and has covered 16000 miles since new April 22. Lexus Reading are going to  check it over and also make sure no drain from towbar. Car used monthly with trailer, but always locked, indeed it's now back to normal and left event this Saturday under its own steam !

[rayaans]

You guys really need to try turning the Lexus Link off entirely and seeing how it goes - its very likely its causing drain and its a well known cause of the drain too (as are all car connective apps). 

My UX300e was draining batteries out within a week until the connected services were turned off. Hasnt missed a beat since.

[DBIZO]

17 minutes ago, rayaans said:

You guys really need to try turning the Lexus Link off entirely and seeing how it goes - its very likely its causing drain and its a well known cause of the drain too (as are all car connective apps). 

My UX300e was draining batteries out within a week until the connected services were turned off. Hasnt missed a beat since.

There you go, makes perfect sense, and an example of how making things more complex undermines core reliability / availability. I even turned off keyless entry in part for this reason, but also for the added security against theft, although the car now hitting 8 years, I don't think it's in demand by thieves.

[Warthog001]

I stumbled on this thread a couple of days ago  after collecting my new 450h+ on Thursday and I am very glad to know that the power drain on the 12v Battery is potentially a problem if not managed.  I only drive short distances and have had the same issue on my last 2 cars. I, like many others, thought that the power from the wall socket would charge the aux Battery - wrong!  

My solution is to connect an LED voltage meter that plugs into the 12v outlet in the cubby under the phone charger (about £6.50 from amazon).  When the car is in 'accessory' mode it will show the voltage from the aux Battery and in 'ready' mode the system voltage (not of interest here). Slide back the charger drawer and the display can easily be seen.  If the reading is 12v (my comfort level) or below, it's time to use an external charger to boost the Battery.  It doesn't matter if the cheap voltmeter is inaccurate and reads too high or low as it can be 'calibrated' by using a multimeter reading from the Battery when its first installed, the error is likely to be fairly consistant - mine reads 0.2-0.3v higher so I take that into account.

After only 4 days of ownership my Battery was down to 11.7v and needed a serious charge.  Probably due to dealership demo and initial setup accessory mode. 

Thanks to all contributers as your info has saved me from being stuffed with a flat Battery only a couple of weeks after taking ownership of what seems to be a great car.

 

 

[hintonwood]

I did the same as Neil and purchased the voltage meter for £6.49.

After 2 x 20 minute drives yesterday it showed 11.8v. I took my multimeter and tested across the Battery terminals and the reading was 11.94 so the device was showing .14v light.

Today I again did 2 x 20 minute journeys. The Battery voltage at the terminals is 11.96v. The voltage when charging is 14.4v

I am concerned that a normal voltage for a fully charged car Battery is 12.8v. Lexus had the car for a day last month after I had to call the AA out when the Battery went flat sitting on my drive for 8 days over Christmas. Lexus said the Battery is perfect and everything is working as expected and no unexpected drain occurring.

I am interested to learn if anyone thinks this can be considered normal voltage for a supposedly ‘healthy’ Battery?

[ColinBarber]

1 hour ago, hintonwood said:

I am interested to learn if anyone thinks this can be considered normal voltage for a supposedly ‘healthy’ battery?

It is either severely discharged or faulty - you should expect to see between 12.6 - 12.8 v when fully charged. I'd certainly expect it to read higher after 80 mins of charging, but that might not be enough to fully charge it, depending on how flat it started out at.

I assume you don't have a Battery charger to fully charge it up? If not you don't actually need to drive the vehicle, you can just leave it in 'Ready' mode for it to charge the Battery - turn off the heating system so the petrol engine doesn't fire up all the time to keep the cabin warm.

[hintonwood]

7 hours ago, ColinBarber said:

 

I assume you don't have a battery charger to fully charge it up? If not you don't actually need to drive the vehicle, you can just leave it in 'Ready' mode for it to charge the battery - turn off the heating system so the petrol engine doesn't fire up all the time to keep the cabin warm.

Yes, Colin, I do have a trickle charger I used to use for my motorcycle batteries on the basis that they were ridden infrequently. I wouldn’t expect to have to use it on a £50k+ car that is driven over 10k miles a year… In any case, my car is too far from the house to plug the charger in.

As advised by the AA and others on these forums, I have been putting the car into ‘Ready Mode’ when hoovering the floor mats or loading / unloading the boot - something I have never had to do with any other car! 

I have raised the matter with Lexus again.

[RXtoNX]

13 hours ago, hintonwood said:

 

As advised by the AA and others on these forums, I have been putting the car into ‘Ready Mode’ when hoovering the floor mats or loading / unloading the boot - something I have never had to do with any other car! 

I have raised the matter with Lexus again.

As others have pointed out, the 12v Battery does not have the capacity that one would have fitted to ICE cars. I found this out the hard way when fitting front & rear dash cams during which I found myself locked inside the car on 2 occasions.
Yes, before the Battery fully depletes it goes in to “protect” mode and locks the car. Not fun having to climb from the front seat through to the boot to be able to use the manual release. 
The low capacity 12v Battery works fine though after leaving the car for 3 weeks at an airport so I guess it does what it is designed to do & now I know what its limitations are I plan accordingly, it doesn’t really present any hardship.

[dts439]

I was surprised/annoyed to discover that the traction Battery did not keep the 12V Battery charged, especially as I always left it plugged in. Has happened a couple of times, locking me out of the car when its been left for 3+ weeks.  Manually opening the car and putting it on charge or attaching a Battery pack eventually got it going again.

Looking at this thread on Club Lexus 450h charging question it shows the car was trickle charging the 12V whilst its charging the hybrid Battery but not when it completes charging.  I'll be manually trickle charging the 12V Battery every so often from now on.

I'd seen a similar type of issue reported on a Kia eNiro EV where software controlled when the 12V Battery was charged from the main Battery but the algorithm it used was flawed and ended up locking people out of their cars as the 12V slowly discharged.

[Mike100C]

12 hours ago, dts439 said:

I was surprised/annoyed to discover that the traction battery did not keep the 12V battery charged, especially as I always left it plugged in. Has happened a couple of times, locking me out of the car when its been left for 3+ weeks.  Manually opening the car and putting it on charge or attaching a battery pack eventually got it going again.

Looking at this thread on Club Lexus 450h charging question it shows the car was trickle charging the 12V whilst its charging the hybrid battery but not when it completes charging.  I'll be manually trickle charging the 12V battery every so often from now on.

I'd seen a similar type of issue reported on a Kia eNiro EV where software controlled when the 12V battery was charged from the main battery but the algorithm it used was flawed and ended up locking people out of their cars as the 12V slowly discharged.

Hi Dave, I too have a 450h+ and I did ask my dealer if when plugged in did it charge the 12V Battery. I was told a definite no! I have fitted a Noco trickle charger with an extension (Noco) directly wired to the Battery. As my car use is relatively irregular I plug my car in when not in use. No issues to date. (Note: I did own a 300h previously and was always getting Battery warning via the app) . It seems to be a common problem with most PHEV and EV's. - See my earlier posts. Picture shows wiring to my 300h Battery, I now use this on my 450h+. Mike.

[rafarules]

Happened to me once after 7000miles of ownership…all down to me sitting in the car doing stuff, when the car was NOT in READY MODE.

Not happened since, but I do now carry a NOCO GB charger just in case I slip up. Fortunately, I had watched a guy have the same issue in his Taycan, and he didn’t know how to get out of the vehicle (he got really panicky). Double pull on the door handle folks😉

[malcolmw]

My firm supplies jump start units to the AA and we have it on good authority that the major reason for call outs on BEVs and Hybrids is the 12V Battery being flat. The manufacturers have been just too penny pinching with the Ah capacity of the 12V (or to save weight).

[Pm4]

Thanks for the Interesting advice, a couple of questions 

1) will the door double pull work on a 450h with a flat Battery? 

2) if I keep a Battery pack in the car, how do I  connect it inside the car?

[ColinBarber]

1 hour ago, Pm4 said:

Thanks for the Interesting advice, a couple of questions 

1) will the door double pull work on a 450h with a flat battery? 

2) if I keep a battery pack in the car, how do I  connect it inside the car?

1 - Yes

2 - Don't. To 'jump' the vehicle, connect your Battery pack directly to the Battery once you open the bonnet.

[Pm4]

4 minutes ago, ColinBarber said:

1 - Yes

2 - Don't. To 'jump' the vehicle, connect your battery pack directly to the battery once you open the bonnet.

👍👍🙏🏻