UX300e 12v Battery woes

[schroder]

23 hours 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.

 

 

 

 

 

I was told not to do this .. connect the NOCO positive to the Battery positive BUT connect the negative to some bare, unpainted bodywork or a convenient bolt, anything that gives a good earth.

Apparently, if you connect both directly to the Battery it can cause issues with electronic circuitry.

[Jim1977]

3 minutes ago, schroder said:

I was told not to do this .. connect the NOCO positive to the battery positive BUT connect the negative to some bare, unpainted bodywork or a convenient bolt, anything that gives a good earth.

Apparently, if you connect both directly to the battery it can cause issues with electronic circuitry.

Was that specific Lexus advice, or jumping 12v in general? I just had a look at the Noco instructions and it does say you can connect to the chassis or the negative terminal. The leads would be long enough to find a suitable connecting point if necessary.

[rayaans]

1 hour ago, Jim1977 said:

Was that specific Lexus advice, or jumping 12v in general? I just had a look at the Noco instructions and it does say you can connect to the chassis or the negative terminal. The leads would be long enough to find a suitable connecting point if necessary.

The handbook suggests using the bare metal piece roughly in the center of the engine bay for the UXe

[schroder]

2 hours ago, Jim1977 said:

Was that specific Lexus advice, or jumping 12v in general? I just had a look at the Noco instructions and it does say you can connect to the chassis or the negative terminal. The leads would be long enough to find a suitable connecting point if necessary.

No, it wasn't advice from Lexus, more 'in general' although copious posts in the Toyota forum regarding this.

[ALAW]

I see that from Thursday Lidl are selling a jump starter £44

[Yorkshire Lexus]

Gents, I suggest…..you should not have to jump start a £55,000 car that is 18 months old , missing the point …..

[Malc1]

18 minutes ago, Yorkshire Lexus said:

Gents, I suggest…..you should not have to jump start a £55,000 car that is 18 months old , missing the point …..

one shouldn't have to do anything to an 18 month young car save servicing regularly and properly .......  whatever the make Marque of car let alone a LEXUS

Malc

[rayaans]

So Ive hooked up the Noco Genius 2A (good discount from Halfords) and it took about 2 hours to fully charge. Currently on maintenance mode but doesnt appear like there's anything majorly wrong with the Battery itself.......

The Battery is tiny though - 32ah standard 12v

[Dedra]

On 1/9/2024 at 6:51 PM, rayaans said:

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

Hi folks, reading these threads seems ludicrous that you buy from Lexus for reliability- well this is why we do, but you can’t go away for a weeks holiday and expect your car to drive.!!! Surely rather than buying chargers and jump start equipment as a back up you should be going straight back to Lexus to say this isn’t fit for purpose. Love my UXe but the 12v has drained twice already!! The reliability selling point is wearing off. This is my 5th Lexus- and first ev, so disappointed!!

 

[SH20]

While the issue of the 12v Battery going flat due to lack of regular use (Time running not distance matters when getting a Battery back to full charge)  the problem exists for conventional petrol or diesel cars too.   It's not just Lexus self charging hybrid vehicles but any car that has multiple electronic control units that require either a constant low amperage supply or more power when booting the car into life.   All exotic models like Bentley, Aston Martin, Jaguar, Mercedes etc always recommend a CTek charger for conditioning the Battery when not in use.   CTek is recommended by all the British Manufacturers even to the point of the car's logo on the unit.   First signs of low Battery voltage in these expensive cars are multiple waring lights on the dash.

I admit my current Lexus car is the only hybrid Lexus out of 6 that let me down with a flat 12v Battery in the last 5 years.   Never gave it a second thought that my car would not start when I press that button.      The traction Battery does all the charging of the 12v Battery but it's the 12v Battery that needs to initiate the starting process to get you in the READY mode to move off. 

There doesn't appear to be any options other than use the car regularly or get into the habit of using a CTek conditioner every 3rd or 4th day if you know the car won't be used for extended periods.  I can't get my car into my garage so run a lead out from the garage to the boot of the car on the drive and connect the CTek.   I lock the car up and just leave it till the CTek shows fully charged even if that takes 4 or 5 hours.   I know then I will be able to move off without an issue.   

 

       

[rayaans]

16 hours ago, Dedra said:

Hi folks, reading these threads seems ludicrous that you buy from Lexus for reliability- well this is why we do, but you can’t go away for a weeks holiday and expect your car to drive.!!! Surely rather than buying chargers and jump start equipment as a back up you should be going straight back to Lexus to say this isn’t fit for purpose. Love my UXe but the 12v has drained twice already!! The reliability selling point is wearing off. This is my 5th Lexus- and first ev, so disappointed!!

 

It's inherently an EV problem. My hybrids were never as poor Battery wise and could be left for weeks without issue.

AA man said 50% approx of callouts now are EV 12V batteries discharged as they keep putting smaller and smaller batteries in. Porsche Taycan seems to be a regular.

[Gregory Z]

Hey all 

 

I bought UX back in July 2023 and already had flat Battery issue twice. First one  has been direct result of dash cam settings but last friday upon return from holidays Battery was dead again (after 2 weeks of car parked at gatwick) and this time its defo not cameras fault (been replaced and correct settings applied)

 

Today afeter speaking to Twickenham Lexus been told that due to very low milage - 2600 the warranty will not cover it should they have to replace it. I'm amazed by such reaponse .. any one has got similar reponse/ experience ? 

Many thanks 

[ColinBarber]

1 hour ago, Gregory Z said:

Today afeter speaking to Twickenham Lexus been told that due to very low milage - 2600 the warranty will not cover it should they have to replace it. I'm amazed by such reaponse .. any one has got similar reponse/ experience ? 

That is a far from ideal response but I can understand the logic. The Battery will be discharged through lack of use, which would affect its capacity and ability to maintain a charge - 12v lead acid batteries do not like being deep discharged. In the eye of the Battery manufacturer, this isn't a warranty issue because it isn't a manufacturing defect, it has inadvertently been user damaged.

I'd argue that a vehicle isn't fit for purpose if you cannot go on holiday for two weeks, so you will have some recourse if you wanted to threaten or take up legal action. However, just replacing the Battery with a new one doesn't solve the issue, and I doubt there is room to fit one with a larger capacity.

[ivancrx]

I have just purchased a UX300e and don’t want to be stuck with a flat Battery.

I understand that it shouldn’t happen with a new car but don’t want to chance it, so I have been looking at boosters, the Noco 20gb and the Noco 40gb. Can’t see a massive difference in them just wandering if any one has the smaller 20gb and how it copes?

[ColinBarber]

4 hours ago, ivancrx said:

I have just purchased a UX300e and don’t want to be stuck with a flat battery.

I understand that it shouldn’t happen with a new car but don’t want to chance it, so I have been looking at boosters, the Noco 20gb and the Noco 40gb. Can’t see a massive difference in them just wandering if any one has the smaller 20gb and how it copes?

The smaller one is fine for any Lexus hybrid or EV because the 12v Battery isn't used to start the petrol engine and therefore it won't draw much power.

You have want a larger one to support other petrol/diesel cars you might own or help out other people's cars.

[RadicalCoupe-Fuji]

I work with these cars & i can confirm that the majority of them need jump starting all the time. Im not sure about UXE but the RX 450+ can die if you jump it wrong, needs a new ECU. 

[ivancrx]

47 minutes ago, RadicalCoupe-Fuji said:

Im not sure about UXE but the RX 450+ can die if you jump it wrong, needs a new ECU. 

That isn’t good news, what is the correct way if you don’t mind me asking? 

[Duggie B]

49 minutes ago, ivancrx said:

That isn’t good news, what is the correct way if you don’t mind me asking? 

Smart chargers are reverse polarity protected ...they won't charge if wrongly connected.

[RadicalCoupe-Fuji]

The rz & bz4x don't have the issues with the Battery, seems like a design issue with the uxe, the cars we get don't even have the dome fuse in so it can't be a drain. You just have to drive it frequently I guess.

[ColinBarber]

22 minutes ago, RadicalCoupe-Fuji said:

The rz & bz4x don't have the issues with the battery, seems like a design issue with the uxe, the cars we get don't even have the dome fuse in so it can't be a drain. You just have to drive it frequently I guess.

Really?

 

[TonyElyod]

On 1/8/2024 at 6:59 PM, 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.

 

 

 

 

Connect Negative to Earth of car and NOT to Negative of  Battery.

You can do allsorts of internal damage

[ColinBarber]

5 hours ago, TonyElyod said:

Connect Negative to Earth of car and NOT to Negative of  battery.

You can do allsorts of internal damage

Doing so is recommended to minimise the risk of igniting any hydrogen that may be produced from the Battery. Makes no difference otherwise. 

[Herbie]

12 hours ago, TonyElyod said:

Connect Negative to Earth of car and NOT to Negative of  battery.

You can do allsorts of internal damage

No, no and thrice no. You cannot do any damage by connecting to the negative Battery post rather than an unpainted bolt/nut/screw/bracket etc., etc., apart from one caveat.

Under certain conditions a Battery can emit hydrogen gas and so create a risk of explosion if a spark were to ignite it. This is why the advice is to clip to an earth point away from the Battery itself, so that any sparks generated will not be in close proximity to the gas cloud (if there is one*).

However, from an electrical point of view, there is no difference whatsoever whether you connect to the Battery terminal itself or to some unpainted nut/bolt etc., etc., at the front, back, top or bottom of the car. Not one jot of difference at all.

*In more than 40 years of hobby spannering I have never personally seen or heard of an explosion being caused in this way, nor have any family or friends.

[Dedra]

On 3/24/2024 at 12:28 PM, Dedra said:

Hi folks, reading these threads seems ludicrous that you buy from Lexus for reliability- well this is why we do, but you can’t go away for a weeks holiday and expect your car to drive.!!! Surely rather than buying chargers and jump start equipment as a back up you should be going straight back to Lexus to say this isn’t fit for purpose. Love my UXe but the 12v has drained twice already!! The reliability selling point is wearing off. This is my 5th Lexus- and first ev, so disappointed!!

 

Hi folks, my issue well and truly sorted. can I suggest that you back to Lexus- they have fully restored my faith in Lexus reliability. Software update and 12v Battery drain sorted!! No more issues back to enjoying my UXe!

[Herbie]

On 7/5/2024 at 3:50 PM, Dedra said:

Hi folks, my issue well and truly sorted. can I suggest that you back to Lexus- they have fully restored my faith in Lexus reliability. Software update and 12v battery drain sorted!! No more issues back to enjoying my UXe!

Hmm...but is it?......Really?

The problem with the 12V Battery drain is that it isn't really a fixable problem, more a design fault that shouldn't ever have got off the drawing board. I don't know what capacity the 12V Battery is in these cars but I'll assume a couple of things for the sake of this example.

All batteries will exhibit some level of self-discharge anway, but we also need to take into account the quiescent current draw when the car is 'asleep'. This is the amount of current drawn for things that need to be kept alive, like the intruder alarm, the radio presets, the seat memory and so on. Modern cars take around 50 milliamps (50mA or 0.05A).

So, let's be generous and say that the 12V Battery has a 50Ah capacity. This means that it can supply 50A for one hour, or 25A for two hours, or 12.5A for four hours and so on. Let's also assume that it's brand new and fully charged, so that:

50Ah divided by a draw of 0.05A = 1,000 hours from fully charged to fully discharged. That's 41.66 days or 5.95 weeks. However, the Battery will not be capable of starting the car well before it's fully discharged, so in reality you'll get a lot less than that 1,000 hours and remember that I assumed a 50Ah Battery. If the capacity is lower then you'll get less again. Also remember that as a Battery ages, its capacity will drop so again, shorter time between charges if it's not used enough.

This is how the car was designed, so you could say it's a design problem or you could equally say that hybrids and/or EVs are just not suited to some people's driving habits. They need to be used on a regular basis or kept on a trickle charger when not being used.