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Rx400H Battery Discharge Overnight, New Battery, Alternator Fine


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Hi all, First post here.

I have a 2006 rx400h purchased with 30k miles 18 months ago. We drive the car a few times a week and regularly on weekends.

The 12V SLI Battery was dead 6 months ago, I figured it was 5yrs old and time for a new one, so i replaced it, this worked for 6 months.

One month ago the Battery was again dead. I Had the car jump started and drove it for a day, the next day it was dead again... bought a trickle charger, took Battery out and charged it in our house overnight, it then worked for a day.. and then was dead again. I took the Battery (6 months old) into Kwik fit, they gave a free replacement. 3 days later the new Battery is dead as well, repeat cycle of jumpstart, drive, trickle charge, etc... dead each morning.

Took car under AA 5-star warranty to a local garage, they looked for 4 days, alternator fine, Battery fine, they cant find a problem.

Have now booked to take it to a lexus for them to look (of course its dead so will need to jump it to get it there). and now its not covered under warranty.

A quick search shows a history of these electronics problems with some ghost draining the Battery overnight... but why all of a sudden after 5 years of no problems and a new 12V Battery? I cant believe that a 'luxury' can needs to be trickle charged with a solar charger each night... never seen a range rover or an X5 with this problem

any help or advice would be appreciated. I'm getting tired of spending my nights unhooking the Battery to bring it in for charge, then the mornings putting it back in so my wife can take the kids to school (parked on public street).

HELP!!!!

Austin

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Hi all, First post here.

I have a 2006 rx400h purchased with 30k miles 18 months ago. We drive the car a few times a week and regularly on weekends.

The 12V SLI battery was dead 6 months ago, I figured it was 5yrs old and time for a new one, so i replaced it, this worked for 6 months.

One month ago the battery was again dead. I Had the car jump started and drove it for a day, the next day it was dead again... bought a trickle charger, took battery out and charged it in our house overnight, it then worked for a day.. and then was dead again. I took the battery (6 months old) into Kwik fit, they gave a free replacement. 3 days later the new battery is dead as well, repeat cycle of jumpstart, drive, trickle charge, etc... dead each morning.

Took car under AA 5-star warranty to a local garage, they looked for 4 days, alternator fine, battery fine, they cant find a problem.

Have now booked to take it to a lexus for them to look (of course its dead so will need to jump it to get it there). and now its not covered under warranty.

A quick search shows a history of these electronics problems with some ghost draining the battery overnight... but why all of a sudden after 5 years of no problems and a new 12V battery? I cant believe that a 'luxury' can needs to be trickle charged with a solar charger each night... never seen a range rover or an X5 with this problem

any help or advice would be appreciated. I'm getting tired of spending my nights unhooking the battery to bring it in for charge, then the mornings putting it back in so my wife can take the kids to school (parked on public street).

HELP!!!!

Austin

It will be nothing whatever to do with what type of car it is, luxury or otherwise and age is a factor, something has failed. However the most humble car can suffer from these problems so that assertion is wrong. It can be a host of things and a dealer is best placed to sort it and will have the knowledge of how to cheque individual circuits to try to pin it down..

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thanks. So does it sound to you that its a short circuit somewhere that is leading to a slow Battery discharge overnight? I have heard that the Sat Nav or instrument panel has had this problem a few times. thus far we have established its not the Battery, dome lights, or alternator... so must be some fault elsewhere.

thanks again.

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It does sound like faulty equipment draining the Battery. It happens across all makes cars. I've seen it all too often. Electronics are electronics.

If you want to diagnose it yourself, you can start by leaving fuses out (do it a bank at a time rather than individual it will be a lot easier and quicker).

Do you have a multimeter? There are more tests you can do and tie it down very quickly.

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  • 1 month later...

Hi all,

to give you an update on this... no resolution. Lexus service has now had the car on and off for 8 weeks! the Battery is intermittently dead every 2 or 3 days, and we are now on the 4th Battery in 6 months. the lexus mechanics have never seen this problem in 20 years. they cannot find what is causing the drain, yet can record that it is happening. they tested it every day for 3 weeks. This is not some joe-blow auto shop, its the proper lexus dealer. Even the guys from Japan dont know what is wrong.

the car was fine for 2 weeks (they didnt know why it suddenly went away) (jan 1-14), and the Battery dying problem has now come back again. something is very wrong. the car has no accident or flood history and has been fully maintained. This is costing me a fortune... £130/hr work, and insurance wont cover it, AA warranty covers only 40£, its basically a chunk of steel.

So i am out £20,000 on a car that wont drive, they cant find what's wrong, it cant be fixed, I cant sell, and cant scrap, and insurance wont cover. its basically scrap.

PLEASE BE WARY OF THIS> the RX400H has major Battery problems we all know about... but mine is an example that it can get MUCH WORSE. The car is totally useless. If you buy an RX 400 you risk losing every penny you have spent on it, with zero residual value.

any other suggestions or advice before i sell for scrap?

thanks,

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This is an issue witha specific car rather than the model and should be seen in that light however frustrating it is to the owner. It does not really relate to the known Battery problems the model has in some circumstances and should not be judged as part of that.

As the car is presumably second hand can you not return to the supplying dealer as not fit for use? These issues will surely not have started suddenly so surely someone knows more than is being revealed to you.

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The intermittent nature of this issue makes it very difficult to find the root cause. As Geoffers has suggested, removing fuses to narrow down where the problem lies is probably the best approach.

It could be possible to data log the drain on the Battery. The amount of current suddenly being consumed could give a clue to what is causing the issue.

Monitoring the vehicle on CCTV could also be useful to determine if any lights are intermittently coming on during the night and if audio is available then you could check for hybrid/brake pump operation, alarm, horn etc.

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i would also seek legal advise regarding your warranty.

My understanding is that if a fault is reported within the warranty period it doesn't matter if it then goes out of cover, they are still obligated to resolve the issue. If this wasn't the case then warranty companies would purposely delay fixing issues until cover ran out.

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i would also seek legal advise regarding your warranty.

My understanding is that if a fault is reported within the warranty period it doesn't matter if it then goes out of cover, they are still obligated to resolve the issue. If this wasn't the case then warranty companies would purposely delay fixing issues until cover ran out.

Indeed so the critical issue is to report it during the warranty validity. After that liability is fairly open ended as long as the fault is continuous.

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Just read for a similar problem (Although not RX, but IS was affected) - the solution was removal of the fuse for headlights washing.

Which now means you would fail the MOT - remember to put it back in before going for the pointless inspection!

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Just read for a similar problem (Although not RX, but IS was affected) - the solution was removal of the fuse for headlights washing.

Which now means you would fail the MOT - remember to put it back in before going for the pointless inspection!

I didn't say he should leave it off, just a hint of where he might start looking. If it is the headlight washer module - it can be replaced or bypassed easily. As it is described here: http://www.infoarena.com/lexus/HWMod/

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  • 2 weeks later...

Every time you lock the car up (at night helps) check to see if the window switches are illuminated (they shouldn't be). We had one that had a intermittant short in the drivers wiring loom as water was getting in.

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  • 1 year later...

hi all, I am the orig poster here. thought I would give an update.

well after many many months of frustration, about 7 trips to the local lexus dealer, many weeks without a car, etc, etc... the service technicians decided to put a new OEM 12V Battery in the car. This is after we had used several different off the shelf store bought batteries, which kept draining and dying as described above.

And I am happy to say that after more than 1yr now, the problem has not recurred and its been all but forgotten.

So the lesson learned here, is that perhaps one should spend the extra 30£ to buy an OEM Battery rather than a cheaper one from a local car shop.

thanks to everyone for your replies and views.

safe driving.

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Confused - what is the possible difference between an OEM Battery and an 'off-the-shelf' Battery (unless it was a real bargain bucket battery)? The OEM will just have a different sticker on it - if there really was a difference, the dealer would have been the first to tell you (they love blaming problems on non-OEM parts).

I seriously can't believe that was the issue - my guess is water somewhere causing a short, which finally dried out and the new Battery was just a coincidence.

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  • 6 years later...
On 2/28/2014 at 11:04 AM, austin brown said:

hi all, I am the orig poster here. thought I would give an update.

well after many many months of frustration, about 7 trips to the local lexus dealer, many weeks without a car, etc, etc... the service technicians decided to put a new OEM 12V Battery in the car. This is after we had used several different off the shelf store bought batteries, which kept draining and dying as described above.

And I am happy to say that after more than 1yr now, the problem has not recurred and its been all but forgotten.

So the lesson learned here, is that perhaps one should spend the extra 30£ to buy an OEM Battery rather than a cheaper one from a local car shop.

thanks to everyone for your replies and views.

safe driving.

Hi we have been having a similar issue with the same model. Was this really the issue?? And was it a long term solution? Thanks

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4 minutes ago, LondOz said:

Hi we have been having a similar issue with the same model. Was this really the issue?? And was it a long term solution? Thanks

As stated, it wasn't an issue other than faulty batteries that couldn't hold a charge.

If you suspect you have a problem then get an auto electrician to measure the parasitic load of the vehicle after it has been locked for 20 mins. You shouldn't see more the 50 mA being consumed. If it is more then the circuits will have to be diagnosed to determine what component is consuming power.

Make sure you Battery is clean and dirt free.

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1 hour ago, ColinBarber said:

As stated, it wasn't an issue other than faulty batteries that couldn't hold a charge.

If you suspect you have a problem then get an auto electrician to measure the parasitic load of the vehicle after it has been locked for 20 mins. You shouldn't see more the 50 mA being consumed. If it is more then the circuits will have to be diagnosed to determine what component is consuming power.

Make sure you battery is clean and dirt free.

Thanks a lot. It is actually now at an auto electrician and they are stripping the whole boot to check the issue. I will ask them to try this as well. 

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