12V battery problem

[ColinBarber]

On 3/14/2024 at 2:30 PM, Simpson Iain said:

Is there a critical voltage below which the car will not go into ready mode?

probably around 11.8 V but ideally you don't want it to drop that low as it will be quite heavily discharged at that point, causing damage to the Battery in a reduction in usable capacity. Even at 12.1 V it means the Battery has discharged over 50% which isn't good and it only taking 2 days to fall that low probably indicates it has lost some of its capacity already.

[Simpson Iain]

After monitoring the resting Battery voltage for two weeks I changed the Battery this morning. It was a fairly straight forward job. No error codes or messages after the change. The old Battery was a Panasonic the new Battery is a Yuasa YBX5027 sealed Battery from the local GSF car parts depot.

[Mike100C]

3 hours ago, Simpson Iain said:

After monitoring the resting battery voltage for two weeks I changed the battery this morning. It was a fairly straight forward job. No error codes or messages after the change. The old battery was a Panasonic the new battery is a Yuasa YBX5027 sealed battery from the local GSF car parts depot.

Hi Iain, good to know that the change was completed without any issues, always a potential problem in today's vehicles. Keep us up to date with future progress please. Mike

[Solihullman]

Hi David

How did you (or the AA) manage to get to the Battery? With no, or low, Battery the boot can't be opened as there is no mechanical system (as there is for the doors). I have had the same problem and the AA man had to wiggle his way via the back seats.

[Husky125]

There is a charging point to jump start them in the engine bay, no need to gain access to Battery.

Details are in the handbook ,showing the correct places for each lead.

[Muff12]

I have an RX450h+, I have the same issue that I have taken up with Lexus several times. I have had to buy a jump start unit to carry around with me.

I recently had it serviced (first service) and booked it in to check the 12v Battery and its capacity. They had it for 3 days. When I collected it I had a lenghthy discussion with the service manager about it. He said they had done a full discharge and recharge, how best to prevent it etc. I got home, put a bettery tester on it - 65% charge!

 

[hintonwood]

17 hours ago, Muff12 said:

I have an RX450h+, I have the same issue that I have taken up with Lexus several times. I have had to buy a jump start unit to carry around with me.

I recently had it serviced (first service) and booked it in to check the 12v battery and its capacity. They had it for 3 days. When I collected it I had a lenghthy discussion with the service manager about it. He said they had done a full discharge and recharge, how best to prevent it etc. I got home, put a bettery tester on it - 65% charge!

 

I seem to recall that on the US owners forum someone said that testing the Battery will not give a valid reading unless it is completely free of all leads, i.e. bare terminals only. I don’t want to risk losing settings so have never isolated mine.

I called the AA twice last year and Lexus had it for testing twice. The second time, they said everything is fine but had found a parasitic drain from the dash cam that they fitted. Now corrected, they said.

I now leave the car in ready mode when loading it with luggage or washing it. I also carry an emergency booster in the actual car rather than in the boot - the boot doesn’t unlock electrically if the Battery fails. 

Not ideal on a £50k+ car but that’s where we are.🤬

[Muff12]

On 10/2/2023 at 10:10 AM, JayWales said:

It really does seem to be a tiny battery! 😞
I've had issues with it from having the car valeted, doors open long enough drains it.
Also my Blackvue camera in parking mode killed it, even with the option to turn it off with low battery. I think it just drops too quick for the camera to sense it and turn it off.
So had to turn that feature off which is a shame.

I became an expert at the manual unlocking of the doors, and now have a battery pack in the glovebox just in case - Don't put it in the boot, can't get in if battery dead 😄

I have the same issues as you, I have a new RX450h+, the 12v Battery is only 345amps, I have also been locked out on 3 occasions and now carry a Battery pack. I have had several discussions with my local dealership about the problem, but Lexus aren't bothered, they keep their showroom cars on trickle charge and have suggested I do the same if leaving the car for any length of time. They also suggest when washing the car that I start it and leave it running on EV whilst doing so. I have a Nextbase camera, but do not use parking mode for that reason. I have just relocated my Battery pack from boot to glovebox - thank you.

[Warthog001]

I'm a 3k miles a year driver and do all of the Battery 'management' stuff like using 'ready' when cleaning etc. and, yes, I can keep the Battery at about 12.5v with the help of a Battery momitor - fantastic!!  The point is that why should we have to do this on a £60k car !!!!!!  Toyota/Lexus Battery management system isn't fit for purpose.  Its's a shame as the car is brilliant in almost every other respect and I love the drive quality.

[Muff12]

12 hours ago, Warthog001 said:

I'm a 3k miles a year driver and do all of the battery 'management' stuff like using 'ready' when cleaning etc. and, yes, I can keep the battery at about 12.5v with the help of a battery momitor - fantastic!!  The point is that why should we have to do this on a £60k car !!!!!!  Toyota/Lexus battery management system isn't fit for purpose.  Its's a shame as the car is brilliant in almost every other respect and I love the drive quality.

I do about 5k a year and totally agree with you. At the very least they should upgrade the software to monitor the 12v Battery and output to the App

[RONNIE W HODGEKINSON]

On 10/2/2023 at 10:10 AM, JayWales said:

It really does seem to be a tiny battery! 😞
I've had issues with it from having the car valeted, doors open long enough drains it.
Also my Blackvue camera in parking mode killed it, even with the option to turn it off with low battery. I think it just drops too quick for the camera to sense it and turn it off.
So had to turn that feature off which is a shame.

I became an expert at the manual unlocking of the doors, and now have a battery pack in the glovebox just in case - Don't put it in the boot, can't get in if battery dead 😄

Really Sensible Thing To keep it in The Glove Compartment..WHY would you want to put it in The Boot when you can,t Access it Easily if the 12v Battery Fails....My Opinion Only Of Course !!!

[Warthog001]

On 5/18/2024 at 7:56 AM, Muff12 said:

I do about 5k a year and totally agree with you. At the very least they should upgrade the software to monitor the 12v battery and output to the App

Technically, easy to do but I guess that would be like admitting that there is a real problem and then they would have to work on a fix or face legal action, particularly in the US!  Far easier to fob it off as a product of low-mileage usage.  To be fair, the same issue exists for many EV and PHEV cars from other manufacturers - just not quite as bad as reports from Toyoya/Lexus forums.  Maybe, we are just a picky lot as not much else goes wrong with our vehicles that is worthy of a good moan - the Government, Royal Mail and the NHS being outside the scope of this forum!

[RONNIE W HODGEKINSON]

On 9/30/2023 at 9:31 AM, Scotlex said:

I'm not sure if you constantly run on battery (no petrol engine) the 12v "engine battery" will eventually go flat.

You would think that "the car" would monitor everything and run the engine when required or at least give you some sort of warning.

You Would Think So Alister.. But I Don,t Think It Does Warn You... Crikey It Warns You About Everything Else..Have you Gone on You Tube Or Google and you Might just find the Answer....Imagine Heaven Forbid if the car had gone on fire That would have been potentially Deadly....  It Would be a Steak Pie Situation...Oh.. Check your Manual and see if that comes up with The Answer....!!!!!

[Hayzee]

7 minutes ago, RONNIE W HODGEKINSON said:

You Would Think So Alister.. But I Don,t Think It Does Warn You... Crikey It Warns You About Everything Else..Have you Gone on You Tube Or Google and you Might just find the Answer....Imagine Heaven Forbid if the car had gone on fire That would have been potentially Deadly....  It Would be a Steak Pie Situation...Oh.. Check your Manual and see if that comes up with The Answer....!!!!!

The 12v Battery is charged by the traction Battery when the car is in ready mode. There is no alternator on the car so you can run in EV mode all the time and still charge the 12v Battery. The main issue is that you need to be in ready mode regularly so e.g. not using the car for several weeks can lead to a flattish 12v Battery.

[RONNIE W HODGEKINSON]

2 minutes ago, Hayzee said:

The 12v battery is charged by the traction battery when the car is in ready mode. There is no alternator on the car so you can run in EV mode all the time and still charge the 12v battery. The main issue is that you need to be in ready mode regularly so e.g. not using the car for several weeks can lead to a flattish 12v battery.

Thanks for that info Colin.. BUT does it warn you that the Battery is running low IF you are NOT in Ready Mode Think Thats What Alister Wanted to Know I,m Just Guessing That it Does not......

[Hayzee]

38 minutes ago, RONNIE W HODGEKINSON said:

Thanks for that info Colin.. BUT does it warn you that the battery is running low IF you are NOT in Ready Mode Think Thats What Alister Wanted to Know I,m Just Guessing That it Does not......

No it doesn't Ronnie. Some on the RAV4 forum have bought cheap ammeters that plug into the 12v socket in the dash but this will only show the state of the 12v Battery when in Accessory or ready mode. But at least that may give forewarning of a depleting Battery.

[DavidCM]

There is a Bluetooth Battery monitor available from eBay for about £12.Made or sold as Vgate.It is a small plastic box,about the size of a matchbox,but 1/2 the thickness .It connects to the Battery terminals with a ring fixing and when you activate Bluetooth from your phone using the app, it gives you the voltage.

There is also a mode to show the voltage on startup..you need to force it to start the engine by going into drive and that usually starts the engine.

I can check my voltage from the living room with the car in the carport.. at about 40..50 feet away,easier than  getting the multimeter out,going up to the car,opening the Battery compartment and poking the Battery with the probes.

[RONNIE W HODGEKINSON]

27 minutes ago, Hayzee said:

No it doesn't Ronnie. Some on the RAV4 forum have bought cheap ammeters that plug into the 12v socket in the dash but this will only show the state of the 12v battery when in Accessory or ready mode. But at least that may give forewarning of a depleting battery.

Thought As Much Colin But Wasn,t Really Sure To be Honest..!!!

[RONNIE W HODGEKINSON]

On 3/14/2024 at 6:04 PM, ColinBarber said:

probably around 11.8 V but ideally you don't want it to drop that low as if will be quite heavily discharged at that point, causing damage to the battery in a reduction in usable capacity. Even at 12.1 V it means the battery has discharged over 50% which isn't good and it only taking 2 days to fall that low probably indicates it has lost some of its capacity already.

Gosh My Indicator for the 12v Battery voltage on the DB2 Tracker is only Stating the Battery level at 12.1 However i have NEVER had any Battery Problems since i bought the car and the Battery looks in Pristine Condition...You,ve got me thinking now Colin.....!!!!!

[Hayzee]

On 5/20/2024 at 1:54 PM, RONNIE W HODGEKINSON said:

Gosh My Indicator for the 12v Battery voltage on the DB2 Tracker is only Stating the Battery level at 12.1 However i have NEVER had any Battery Problems since i bought the car and the Battery looks in Pristine Condition...You,ve got me thinking now Colin.....!!!!!

Ronnie.....I just checked mine using a Voltmeter across the Battery terminals and it's at 12.2v which means about 60% charged. My NX is used every day spending at least 30-40 mins in ready mode so I expected the Battery to be in a better charge state than that. I understand (correct me if anyone knows otherwise) that the vehicle will charge the 12v Battery to a maximum of 80%. The car will be idle soon for at least 7 days so I've decided to charge the 12v Battery using my CTEK charger beforehand.

[Muff12]

14 hours ago, Hayzee said:

Ronnie.....I just checked mine using a Voltmeter across the battery terminals and it's at 12.2v which means about 60% charged. My NX is used every day spending at least 30-40 mins in ready mode so I expected the battery to be in a better charge state than that. I understand (correct me if anyone knows otherwise) that the vehicle will charge the 12v battery to a maximum of 80%. The car will be idle soon for at least 7 days so I've decided to charge the 12v battery using my CTEK charger beforehand.

I have just done to very same thing with my RX after finding yet again that my %age was down to 50 so using my CTEK charged it to 95%. Given that you also have a CTEK, I have installed the ring connectors that came with it permanently to the 12v Battery, so now I just plug it in when I want to charge it, much easier and guaranteed a better connection.

[Hayzee]

13 minutes ago, Muff12 said:

I have just done to very same thing with my RX after finding yet again that my %age was down to 50 so using my CTEK charged it to 95%. Given that you also have a CTEK, I have installed the ring connectors that came with it permanently to the 12v battery, so now I just plug it in when I want to charge it, much easier and guaranteed a better connection.

Michael....how often are you having to charge the Battery?

[RONNIE W HODGEKINSON]

Small Point Of Interest If you have a Noco boost Power unit..!!!!! DO NOT Leave it in The Boot.. Put It In Your Glove Compartment..!!!!

[Muff12]

23 minutes ago, Hayzee said:

Michael....how often are you having to charge the battery?

Difficult to say, however during the winter months I do every few weeks due to poor Battery performance in cold weather. However it has just been serviced (last week) and as I have been complaining about it sice I had the car they had it in for a few days and whilst there reconditioned the 12v Battery. I recharged it yesterday as it was down to 50%. When I tested it the following morning it was up to 95%, so I can only conclude that reconditioning it does improve its capacity. CTEK do recommend it done annually, I have been reluctant to do it with my previous Mercedes, but I will be reconditioning this one in future.

[Muff12]

On 2/16/2024 at 6:29 PM, Ken R said:

Anybody willing to share what they are achieving in m/KwH and fuel consumption when using the ICE on their RX450h+ to see how it compares with the equivalent NX?

 

On 2/29/2024 at 10:24 AM, Andy B said:

The only slight issue with connecting to Lexus' suggested jump starter terminals under the bonnet (notably point D as referenced in the manual) is that the jump leads provided with most jump starter packs are notoriously short so may not stretch that far.