UX300e 12v Battery woes

[rayaans]

So the 12v Battery on the UX300e is tiny. 

I went on holiday for 12 days thinking it should be fine - obviously was discharged on my return. 

It was started by AA and I took it for a 15 min drive thinking that would be enough to sort it out - unfortunately wasnt and 1 day later it discharged itself.

2 questions really - what is the best solution for this? a trickle charger and any recommendations (ive never used one so don't even know where to start and how to set it up) or something else?

[peniole]

Can you turn off communication/ota updates with lexus? That seems to be a common problem with other ev marques draining their 12v.

[Slucky]

I had the same issue as well, and the AA person did say the Battery on the UX was small. 
He did however recommend to start the car and keep it on for an 1 hour when not being used, as the main Battery would charge the 12v Battery and also keep an backup Battery jump starter just in case. 

[rayaans]

1 hour ago, peniole said:

Can you turn off communication/ota updates with lexus? That seems to be a common problem with other ev marques draining their 12v.

Its already off

I had an issue 6 months into ownership where the Battery would discharge every 3 days despite being driven daily. I turned it off an its been fine since.

So the Battery today when AA man came was at 6V. With car locked and key away it was using 0.5V so no parasitic drain as such.

Car was charging the Battery at 16V when it turned on but this went down to 9.5V. 

Ive taken it out for a 20 mile journey to see what happens. 

12 minutes ago, Slucky said:

I had the same issue as well, and the AA person did say the battery on the UX was small. 
He did however recommend to start the car and keep it on for an 1 hour when not being used, as the main battery would charge the 12v battery and also keep an backup battery jump starter just in case. 

Which Battery charger have you got? Im thinking either a jump starter pack or a trickle charger

[Slucky]

2 minutes ago, rayaans said:

Which battery charger have you got? Im thinking either a jump starter pack or a trickle charger

Noco Boost - Most popular on amazon

https://www.amazon.co.uk/NOCO-GB20-UltraSafe-Lithium-Gasoline/dp/B015TKPT1A/ref=sr_1_8?crid=2RTTV1679HDEK&keywords=noco+jump+starter&qid=1704656008&sprefix=noco%2Caps%2C177&sr=8-8

[rayaans]

19 minutes ago, Slucky said:

Noco Boost - Most popular on Amazon

https://www.amazon.co.uk/NOCO-GB20-UltraSafe-Lithium-Gasoline/dp/B015TKPT1A/ref=sr_1_8?crid=2RTTV1679HDEK&keywords=noco+jump+starter&qid=1704656008&sprefix=noco%2Caps%2C177&sr=8-8

Nice one, looks like a good bit of kit and certainly small enough to keep in the car

[hieronymous]

After 12 years of variously owning 2 Prius’s, a Nissan Leaf, a MY2019 Hyundai Kona EV (current) and a MY2021 IS 300h (current), with no 12v problems, my 2 cents worth is:

Your biggest problem is lack of information, on a daily basis you have no idea what your 12v is doing. This didn’t matter in ICE cars with large cranking capacity - it certainly does with EVs/hybrids.

Meter testing only provides a voltage at one point in time, whereas you need Battery history over days/weeks to look for patterns of behaviour.

Solutions such as the Noco are last resort, the “ambulance at the bottom of the cliff”. You still have no idea if/when your 12v is going to fail, and if it has failed once, then it is more likely to again.

As in life, solutions of the “primary care at the top of the cliff” sort, are the way to go. The one I use is the BM2 Battery monitor, usually widely available on amazon, eBay etc. It runs 24/7 on the 12v terminals with minuscule drain, records full voltage history for months at least, provides 1 day / 7 day charting, and feeds all this to an Android/IOS app via Bluetooth. It is widely discussed on many EV/hybrid forums.

I have 1 of these for each car, for daily perusal over breakfast. So EASY.. Both have been continuously running since 2021, totally reliable.

Highly recommended!!

 

[ALAW]

Sorry to hear this Rayaan if you remember i put a thread up about the 12v Battery discharged on return from hol with the UX parked at airport i think i named it 12v Battery anxiety. See if you can find it i had some good replies. I found also lexus do a solar charger that you plug in under steering wheel/dashboard area  there's a proper usb i think to connect to then the solar trickles to the 12v. The other option is to carry a jump starter. That raises a few questions in itself where to jump from.  

[SH20]

Hadn't given a lot of thought to the demands of a 12 v Battery in all 6 Lexus hybrids I've owned until yesterday when my LS500h went flat totally after 5 weeks of ownership.  The car was a pre owned Lexus approved car but all previous 5 hybrids never once went flat regardless of how long they were left unused.   

Just ordered a small Jump pack from Machine Mart which I will now carry with me.  The AA came out within 40 mins and spoke of the huge number of ECU's and Modems cars have now and the very high spec of this car makes me wonder just how many electrical systems are powered up each time you press that start button.    My Battery went down to 3 volts so total power loss and despite the AA getting it running with a jump pack and I gave it a 40 minute run out I'm not sure the Battery can be saved.  If it starts tomorrow I'll be amazed.  The AA had to clear a large number of error codes due to multiple warning lights flashing away after he started the car and eventually the car returned to normal.   I'm ringing the dealer first thing to test the Battery under the 12 month warranty I got with the car.      

[RONNIE W HODGEKINSON]

8 hours ago, rayaans said:

So the 12v battery on the UX300e is tiny. 

I went on holiday for 12 days thinking it should be fine - obviously was discharged on my return. 

It was started by AA and I took it for a 15 min drive thinking that would be enough to sort it out - unfortunately wasnt and 1 day later it discharged itself.

2 questions really - what is the best solution for this? a trickle charger and any recommendations (ive never used one so don't even know where to start and how to set it up) or something else?

Get a Noco Battery Jump start Unit..What you NEED for this very Situation..You won,t need to call out the AA Because this little piece of Kit Will start your car ..Would,nt leave home Without One I Have the Noco 40 GB.....GET ONE..!!! Check that you haven,t got something switched on that will drain your Battery Ie dashcam OTA Updates etc.. Battery should not deplete within that short space of time 12 days...Could also be a Defective Battery. Garage can check that out for you...Hope that helps..!!!

[stepppy]

I use this one and it works a treat, had it over three years now.

Smart Charger

Whenever I am on holiday I put it on a smart plug and have it doing eight hours 'charge/maintaining' three times a week.  I am still on my original 12V Battery from new (2017).

I also carry a small jump back in the centre console... just in case..

[Jim1977]

I have a Noco Boost GB40. It fits in the glovebox. I can confirm it jumps a totally dead 300e.

You just connect it to the positive and negative terminals on the 12v Battery. Turn it on. Press the boost button if the 12v is too dead for the Noco to detect (I had to do that). Start the car. Then with the car still on, turn off the Noco, then disconnect.

NB positive first, then negative when connecting. 
Negative first, then positive when disconnecting.

 

 

 

 

[rayaans]

1 minute ago, Jim1977 said:

I have a Noco Boost GB40. It fits in the glovebox. I can confirm it jumps a totally dead 300e.

You just connect it to the positive and negative terminals on the 12v battery. Turn it on. Press the boost button if the 12v is too dead for the Noco to detect (I had to do that). Start the car. Then with the car still on, turn off the Noco, then disconnect.

NB positive first, then negative when connecting. 
Negative first, then positive when disconnecting.

 

 

 

 

Great stuff - have one on order

Im just wondering, do any of you have something to prevent the Battery from discharging in the first place? 

[Jim1977]

2 minutes ago, rayaans said:

Great stuff - have one on order

Im just wondering, do any of you have something to prevent the battery from discharging in the first place? 

Something like Stepppy recommends above will do the job. I have one from Aldi which I suspect is a rebranded version of Stepppy’s as the display screen is identical.

I used that overnight in the garage once I’d jumped my 300e to get the Battery back to a full charge and balanced. If not using the car for a while I would put it on again, once full it will just sit and occasionally condition the Battery, it’s designed to be left attached. 

I used mine on our Kia EV and our Honda during the pandemic when the cars were often not used for weeks and weeks. About once a month I would put them on a float charge and never ran into any issues.

One of these, plus the Noco, covers you with prevention and if the worst happens cure. No need to worry about the 12v letting you down then 👍

[Yorkshire Lexus]

Hi well I’m on my 3rd Battery on my Lexus Uxe, mine wouldn’t start yesterday AA came out, said Battery was absolutely shot and needs a new one, the AA WONT recover you to a Lexus Dealer, all they do is jump start the car , they also WONT fit a new Battery in cars that are currently under warranty. The problem is the Battery will show charge when I drive it to a Lexus Dealer ? 

It’s very frustrating this Battery issue especially as I’m going to be on my 3rd Battery after 19,150 miles. 😅

I use the car every day so I don’t understand.

[steve2006]

Has the “parasitic current” drain been checked I.e. what amperage the Battery is using when the car is “asleep” Does it have an aftermarket immobiliser or other non OEM device fitted?
The AA normally connect some computerised gubbins to the Battery on arrival to check its charge level and voltage, could they not perhaps provide you with a printout, report or even just the figures to show your dealer?

[Malc1]

8 minutes ago, steve2006 said:

Has the “parasitic current” drain been checked I.e. what amperage the battery is using when the car is “asleep” Does it have an aftermarket immobiliser or other non OEM device fitted?
The AA normally connect some computerised gubbins to the battery on arrival to check its charge level and voltage, could they not perhaps provide you with a printout, report or even just the figures to show your dealer?

when I recently called out the RAC for Battery issues an email followed specifying ALL the Battery checks and itemised isssues therein

Malc

[Yorkshire Lexus]

The AA have said I will receive a copy , I’ve rang them 3 times and the engineer and I still have not got it , they are useless .

Customer services said it could take 28 days,YES 28 days !!!!

unbelievable, especially as he did the report on my drive and asked me to sigh a PDF report and asked for my email, it should be bloody instant .

[steve2006]

Probably instant if you buy a new Battery off them, 28 days if you decline 😀

[ColinBarber]

On 1/7/2024 at 7:30 PM, rayaans said:

So the battery today when AA man came was at 6V. With car locked and key away it was using 0.5V so no parasitic drain as such.

Car was charging the battery at 16V when it turned on but this went down to 9.5V. 

Sounds like you need a new Battery - that one has probably been discharged too much, it will be damaged and will struggle to hold a charge.

 

18 hours ago, rayaans said:

Im just wondering, do any of you have something to prevent the battery from discharging in the first place? 

If you have mains near the vehicle then a small intelligent trickle charger will stop it discharging. Something like this, possibly with an extension cable if your mains supply is more than a metre away from the vehicle:

https://www.halfords.com/motoring/battery-maintenance/battery-chargers/noco-genius1-1-amp-battery-charger-230262.html

 

Alternatively a solar charger that plugs into the OBD port will prevent, or at least slow down, discharge - although probably not much use at this time of year with lack of sunlight.

[rayaans]

9 minutes ago, ColinBarber said:

Sounds like you need a new battery - that one has probably been discharged too much, it will be damaged and will struggle to hold a charge.

 

If you have mains near the vehicle then a small intelligent trickle charger will stop it discharging. Something like this, possibly with an extension cable if your mains supply is more than a metre away from the vehicle:

https://www.halfords.com/motoring/battery-maintenance/battery-chargers/noco-genius1-1-amp-battery-charger-230262.html

 

Alternatively a solar charger that plugs into the ODB port will prevent, or at least slow down, discharge - although probably not much use at this time of year with lack of sunlight.

Will have to see. Car is under 3 years old so wouldn't expect a Battery to die on any car during that time. 

Solar charger wont be any good as the car is garaged. There is a mains about 3m from the vehicle so will have to use an extension lead. 

[Malc1]

3 hours ago, Yorkshire Lexus said:

The AA have said I will receive a copy , I’ve rang them 3 times and the engineer and I still have not got it , they are useless .

Customer services said it could take 28 days,YES 28 days !!!!

unbelievable, especially as he did the report on my drive and asked me to sigh a PDF report and asked for my email, it should be bloody instant .

P’raps the RAC is consummately better than the AA …… 

I’ve been an RAC member since 1967 ……. get free full membership now it seems …… maybe my longevity plays a part in quality service from them, the RAC 

Malc 

maybe you should dump the AA and join the RAC  🤔

[ColinBarber]

1 hour ago, rayaans said:

There is a mains about 3m from the vehicle so will have to use an extension lead. 

In that case you can use a normal mains extension lead, rather than needing an extension cable on the charger output 👍

[Yorkshire Lexus]

Can’t dump the AA, Lexus Assistance is contracted to them unfortunately, they are very poor , the service is appalling 

[rayaans]

8 hours ago, steve2006 said:

Has the “parasitic current” drain been checked I.e. what amperage the battery is using when the car is “asleep” Does it have an aftermarket immobiliser or other non OEM device fitted?
The AA normally connect some computerised gubbins to the battery on arrival to check its charge level and voltage, could they not perhaps provide you with a printout, report or even just the figures to show your dealer?

All it's got is a dash cam which is 12v socket powered. It's taking 0.5amp when asleep so not much. 

Weirdly after the 20 mile drive on Sunday, it started first time today so took it for another 15 mile spin and left it on for 60 mins after. 

I've found my starter pack jump set so I could use that potentially. Used to use it for the lawnmower and for emergencies so should be fine.

I'm going to get a trickle charger though as well and give it a full 2 days on there just to get the Battery up if possible. Just been sent a Halfords 15% off code so why not