Flat Battery On 400H Despite Lexus Renewals

[daviddavid]

I am thoroughly disappointed with my 400H as Lexus seem incapable of resolving the Battery problem. The car is always dead after two weeks standing, despite new Lexus supplied batteries.

Please can someone petition Lexus, maybe via publicity in The Press, to issue a recall to resolve the problem.

This Battery problem totally spoils the pleasure of owning this otherwise great car. Thank you. David

[DanD]

Have you tried a larger capacity Battery?

Could it be that the batteries are not actually at fault, but that there is a "leakage" somewhere?

[daviddavid]

There is no larger Battery that Lexus will fit. Or that can be found to safely fit. The problem is inherent in the system itself. David

[DanD]

I agree that the problem is inherent to the design of the car, but do not agree with your comments about the non existence of a larger capacity Battery.

If you do a search in this forum, you will find that it is well documented and that a number of RX drivers have successfully switched to it. I seem to recall that one was fitted by Lexus at a customer's request.

I do not have the time to dig out links for you, but the Battery is made by Bosch. Maybe do a search on that and see what comes up... good luck...

[ISJason]

hello, i have never had a problem with my RX400h Battery. Are you leaving on any lights or anything extra while your away from the car?

[daviddavid]

Hi Jason,

Thanks for suggestion, but no, everything correctly switched off, as proved by Lexus own tests.

It's been repeatedly happening, despite full Lexus check over and new Lexus batteries.

Lexus agent confirms that it is a real common problem, for which there is no known fix!

I have been advised to carry a spare Battery and use jump leads, or phone RAC/AA if leaving unused for a week or two.

Apparently, once it happens, you can never solve it, however many new Lexus/ Toyota batteries you keep buying from them.

HELP neded from someone who owns a 400H, and who has repeatedly had the same problem- and solved it!

Thanks,

David

[daviddavid]

Dan. Thanks indeed to Dan re Larger BOSCH Battery.

Thanks Dan- I have asked my Lexus but they will not agree to it.

I will try to find the Bosch reference, but would really appreciate anyone letting me know its reference number.

Thanks all.

David

[teejaybee]

Bought one from euro parts, stick in your reg and hey presto. It's best just to get one and forget any Lexus Battery.

[nelmo]

Please can someone petition Lexus, maybe via publicity in The Press, to issue a recall to resolve the problem.

...er...why don't you do it?

How many times has this happened? To be honest, if I was you, I'd change the car - it's obviously not fitting with your lifestyle ie. being regularily away for 2 week periods. It's a known problem which will affect a very small number of people (like you) and is never likely to be resolved, for that reason.

[daviddavid]

Please can someone petition Lexus, maybe via publicity in The Press, to issue a recall to resolve the problem.

...er...why don't you do it?

How many times has this happened? To be honest, if I was you, I'd change the car - it's obviously not fitting with your lifestyle ie. being regularily away for 2 week periods. It's a known problem which will affect a very small number of people (like you) and is never likely to be resolved, for that reason.

I only go away two or three times a year, so my expectations are hardly unreasonable.

But leaving it for only a few days at home is also unreliable for starting. Lexus fitted their own Toyota Battery, again, and checked out all the circuitry all OK. They recognised it as a problem, from other customers too - uniquely to the 400H model.

They had no fix to offer, only DIY bodges such as suggested fitting new wiring/ sockets to enable solar charging and/ or night charging. Hardly a professional answer to the problem from a top price, prestige car!

Anyway, assuming no one has a fix, can anyone please identify which models of Bosch Battery which has higher capacity, that can be fitted in. Several folk have found that as being the best practical solution, but have not provided the model reference.

Thank you.

David

[Bluesman]

I have had this happen to my LS400 a couple of times and the Battery was not at fault. On both occasions the car was parked up for two weeks whilst on holiday. Jumper leads got her going and a good run home and everything was back to normal. Mike

[ISJason]

Maybe the answer is to take the car for a good drive for a good few miles before you go on hols. Maybe that will be enough to keep

the Battery alive.

[j8pfc]

A quick google found this....

http://www.lexusownersclub.co.uk/forum/topic/78597-cost-of-new-normal-battery/

[ColinBarber]

yes just get the Bosch one in the link above. Euro car parts normally have a sale every few days/weeks, expect to pay £50 for it when on sale.

It is only slightly larger in capacity, so don't expect miracles, but being left two to three weeks without an issue is achievable.

[CJHYBRID]

Just been on first holiday since I purchased my 2005 Rx400 h se nav. After leaving her at Stansted for 13 days with AA solar trickle charger plugged into ODB2 socket she started first time no issues.

Relieved though as it had been playing on my mind

[Surfbum]

I had the same dead Battery prob on my 2007 400H,I got lexus to permanently power up the socket on the floor and bought a £28 solar charger and leave it plugged into the socket when my car is parked up for vacations and have never had any more dead batteries.

[daviddavid]

Thanks Derek, for your help - much appreciated.

By the way, using fellow group members kindly advice, I bought a new Bosch S4/58 Battery, which did seem an improvement compared to Lexus/Toyota’s own Battery replacement.

I found my local Lexus agency totally unhelpful/ unsympathetic, saying it was a common/ inherent and unsolvable problem for certain owners with the RX 400H model. And that I should plug it into a mains charger every week- really convenient and professional - and impossible at airports.

So, in desperation, my local car electrical whizz kids, Creative Car Sounds in N21, who did as you suggested, and rewired that same floor lighter socket to be permanently in circuit.

I then bought a solar charger - but it is a bit of an embarassment/ inconvenient to use/ store away, especially when taking friends around! Embarassing having to explain that such an expensive car has a design fault and will not start. Also, the solar charger also only worked if I parked in open space, not under an awning.

So, Creative Car Sounds then also fitted a spare Jump Battery in the boot, which they connected directly to the car's own 12v Battery via an isolating switch under the dash.

Now, life is perfect (almost).

If the car won't start, I just flip the isolator switch under the dash, and the car powers up as normal.

Another vital bit of kit is a little LED voltage indicator that sits in the lower lighter socket, (now permanently hard wired in.)

By looking through the car window, I can see the actual voltage in the Battery. Magic.

If it drops below around 10 volts, then I know the car will not start, meaning it is time to instantly recharge the car Battery, using a mains charger, before all windows, alarms, and back door fail. Recently, the voltage dropped to 0.8 volts after standing for 10 days at airport, which can not do my new Battery any good. Slightly worrying that alarms fail too by that time.

As a professional engineer/ scientist, I enjoy solving problems, but not one due to an inherent car design fault.

I still can not believe that Lexus will not recall cars with the problem!

Am I really alone in thinking that this problem is acceptable?

I hope the above notes will help others with a similar Battery problem with their 400H.

Kind Regards.

[Duncan Roberts]

The problem that Lexus faces is that there is simply insufficient room to install a bigger Battery so a recall would not achieve anything.

[daviddavid]

Thanks Duncan. Totally agree. Yes - If only there was room, a much bigger capacity Battery would certainly be a great bonus to hopefully solve the problem 100%.

I notice that the 450H has a huge 70/75 AH Battery which would be lovely. But no under bonnet space in the 400H.

I considered trying to find space in my 400H for an additional Battery. As you say, Definitely No room under the bonet, so I ended up strapping an auxilliary jump Battery inside the boot on the right side, tied in with bungy straps to two most convenient anchor points.

But there does seem to be space inside/ beneath the boot platform flaps, for an auxilliary Battery in parallel, but it would mean Lexus commissioning a custom size Battery to suit. That can not be beyond their resources.

Alternatively, perhaps Lexus could sort out their Battery management system. There is a huge drain on the Battery for about quarter hour when you switch off. And then a high permanent residual drain, presumably running a computer/ security or something?

Or, maybe they could use power from the BIG underfloor Battery, converted down to 12v, to provide that quiescent power.

Seems such a great shame that so many 400H owners have this embarassing situation.

It has cost me several hundred pounds in trying to by pass the problem, by paying for new Lexus batteries/ re-wiring sockets/ heavy cables from boot to bonnet/ solar chargers/ emergency call out at airport/ rescue taxi etc.

I see that some owners have sold up, and gone back to their previous 300/350 models to get over the problem.

What a let down.

I did love my RX300 but, after 100,000 miles and many happy untroubled Lexus years, it was time to change and upgrade to the RH. An otherwise great car- but of no use if not dependable to start.

Drat! I just dread the day in winter, when even my own "best endavour" measures fail to start the car, when away from home.

[Duncan Roberts]

David

Whilst I agree with the principle, it only seems to be a minority who are adversely affected. I am into my second Mark 2 RX - a 400 and have not experienced this issue once with either car. I recall that most threads have failed to reveal numerous users.

[malcolmn5143]

Hi All,

I had this problem some time ago. It turned out to be the fan bearing on the pre-amp (under the back seat) had dried up. For whatever reason the pre-amp was still on after taking the ignition key out. I changed the pre-amp and haven't had any trouble since, even on short journeys.

Hope this helps.

Malcolm.

[daviddavid]

Thanks Malcolm- Most useful info. But however did you find that was happening??

I had sort of wondered whether my car has an unknown drain, but Lexus checked it over in an hour, charged me £50, and then said the current drain was as expected.

But my own in-line current meter proved the Battery would be flat in 2 weeks! I sort of feel that your own drain may be a clue to my own drain. I am off hunting... Thanks again. David.

[j20]

You know, surely many cars, not just the RX 400h will prob have flat batteries after two weeks sitting around... just a thought.

Why not just take the car on a good old run before you intend to leave it sitting to charge the Battery?

[Surfbum]

Hi Ja,

You obviously haven't read all the other posts regarding the dead Battery issues on the RX400H.Its a common fault due to the small Battery and the drain down caused by the electronics security when the car security alarms are activated and the car not run for a week or two.Lexus are aware of it but do not have a fix other than to keep one happy by changing the batteries every time they get a call out.They cured the problem by installing a bigger Battery on the RX450H.

I have finally decided to change my '57 plate 400H in for a new 450H Advance this Saturday...no more solar charger sitting on the dashboard.....YES!!!

[daviddavid]

Thanks Derek- Glad you found a solution to the same problem - albeit by buying a 450H. I assume that was not a reason for purchase.

I see that Lexus.com have a question and answer to this topic on their 450H web site- as below.

Interestingly, it seems from Lexus that you can start a 450H directly from the petrol engine- but not an option possible with the 400H. Unless someone knows otherwise .... Anyone know how?

Enjoy your 450H. Sold your solar charger yet? David.

CAN I LEAVE MY LEXUS HYBRID DRIVE VEHICLE FOR AN EXTENDED PERIOD OF TIME, WHILE ON HOLIDAY FOR EXAMPLE, WITHOUT HAVING TO RECHARGE THE Battery?

Answer. "As with all vehicles, if left for an extended period of time without use, especially in severe weather conditions, it may need recharging. However, in the unlikely event that the Battery discharges completely, the petrol engine will start the car".