Just bought a 2008 400H with 41,000 miles and got to looking today and found the original 12 volt battery. In my past two vehicles they just barely made it 3 years and failed without warning. How many years are folks getting on the factory battery? Should I just go buy a new one and not take any chances?

 

My battery was replaced at about 5 years. I stopped for gas and when I turned the key I had a warning "Place vehicle in park etc." I checked I am in Park went through Park to Brake and back to Park tried it nothing then it finally started. Mentioned it to my son we thought no more of it had no issues till I went to the local hand car wash. The man made motion to me he could not start it. I thought typical "He cannot start a hybrid" nothing new with these guys. well I could not start it either the scangauge www.scangauge.com showed 9 volts got a jump and left it run till I got home called Lexus no warranty went to the local parts store with my son and put in an Optima Yellowtop.

 

3-5 years. Mine is 3 1/2 and tests well.

 

yeah the 06-09 rx400h had it worst with the small 12v battery, if you constantly drive the rx400h, you shouldn't experience any dead battery problem and should last you about 6 years. most common problem with the rx400h dead battery is because the owner doesn't drive the car periods, lets it sit in the garage, and if they do, they only drive it to get groceries and back. you should have lexus do a battery check on it since you bought it. the small 12v battery only takes two dead battery occurences on it to kill one of the cells in the battery.

 

My 2006 went on the road in may 2005 and I replaced the battery in 2009 I think (might have been early 2010). I couldn't leave the door open for 5 minutes with the dome light on without draining the battery. As someone already mentioned, if you get 'place in park to start etc. when you're already in park, that's a good sign that the battery is on it's way out.

The battery group size is also used in 4 cylinder Honda Accords if that helps show how ridiculously undersized the battery is.

 

+1 one of the employees at the lexus i work at...his honda died..and he bought the rx400h 12v battery, and we stuck it in...fits like magic

 

2007 rx400h, bought cpo in June 2009 at 32k miles: 12 volt failed twice in the next 2 weeks. Dealer replaced with no charge (perhaps under warranty, perhaps as an effort at goodwill after delivering vehicle with several other problems). I'll swap it out in another year or so, just as insurance against problems.

 

Battery went dead on my 2006 RX400h, five years old.
Battery replaced at non-Lexus dealership because I was out of town.
Now right side passenger power windows do not work and sunroof controls are inconsistent. Any ideas to avoid an expensive dealership visit to check the electrical system?

 

You need to recalibrate your windows and sunroof, it should be in the manual whenever you disconnect the 12V or it drops below. I think for the windows u roll each window down 1/2 way by using each individual switch and roll it fully up and hold for 5 seconds. Do for all windows and it should work again. Sunroof I think u open it fully open and closed again? can't remember the details.

 

The battery is small because the car no longer relies on that one to start the car. One of the generators does that when it's needed.

 

The answers to how to reset windows/sunroof and (sometimes it's needed) the rear power hatch are all in your owner's manual.

 

True, the 12-volt battery is not actually used to provide power to run the engine or hybrid system.... BUT, it still seems to be 100% necessary to allow the hybrid system to start operating, i.e. when the 12-volt is dead, so is your $40K+ hybrid vehicle. Looks like they would have found a way around that little problem by now...

 

Of course the 12V battery is necessary to get the car to "READY" status, but once it is, the 12V battery is constantly kept charged by the traction batteries.
The reason why many people think it's undersized is that they think it should cope with all sort of 12V requests like keeping the internal light on, ML stereo running, possibly together with the headlights and wipers, while the car is stopped - also for a long(ish) period of time.
It's not meant to work like that. The 400h is supposed to stay on "READY" at all time, while it's being used.
Just do that, and the 12V battery will last MORE than a bigger battery on a non-hybrid car.

 

A business friend of mine just had their original battery from their 06 die, vehicle had about 70K on it.

 

As Lexmex said, drive it and it might last 7 years...whoopie....