starter battery not holding charge

Asked by Jan 04, 2011 at 08:49 PM about the 2006 Lexus RX 400h FWD

Question type: Maintenance & Repair

My son left the dome light on overnight on the Lexux.  We had to jump-start (quite easily) the next day.  Now, we need to jump start the car (again, quite easily) every 3 or 4 days.  I am now using a trickle charger every other night to prevent needing to jumpstart the car.  The battery indicator shows 'blue', which indicates that the battery should be good.

Do I need to replace the battery?

Regards, Rob

13 Answers


The demand on a hybrid starter battery is very heavy - much heavier than a standard car. Since the hybrid system turns the engine on and off multiple times when driving the starter battery has to 'start' the engine more than once per journey. If you are making short trips the starter battery may not have enough time to recharge. But if you have recharged the battery and it is not holding a charge then its time for a new battery. A local battery retailer can test the current battery and tell you if it has failed.

7 people found this helpful.

I've experienced this very issue with the very same vehicle before. Being a Toyota hybrid, the car has TWO batteries you need to take into consideration. The most important is your hybrid battery - that's the thing under your rear bench seats, and the reason there are air vents under the rear seats - those have nothing to do with your climate control. Chances are, that battery in your vehicle is just fine. The one that's causing problems here is the standard 12-volt battery that's present in any conventionally-powered automobile, and serves here to ORIGINALLY start your vehicle when you turn the key, and that's the one you've been jumping. This battery does NOT start the vehicle after you've turned the key - that's where the big hybrid battery takes over. When we experienced this issue with our RX, the vehicle would loose power when run with the key in the accessory position and the engine off after only about 1-2 minutes. The interior lights would flicker, the navigation display would go awry, and the car usually would not start afterward. Even when we avoided ever putting leaving the key in "accessory" it would often fail to start and require a jump. The dealership couldn't figure out the problem, but when they replaced the battery, everything went back to normal. 35K miles later, the car's running fantastically hasn't had a problem since. Good luck!

15 people found this helpful.

I have the very same problem with my 2006 RX400h. It has 65K miles on it so we don't drive it very much, but I have put 6 new batteries in it. This time, I installed a remote start system on it so I can start and idle it for a few minutes each day and I hope this helps. I am desperate and willing to try anything .since I need reliable transportation.

5 people found this helpful.

I have a Lexus 2006 RX 400h and a 2013 RX 450h. I have spoken with different Lexus dealerships about the 2006 400h battery and get different answers. I've had to jump my 2006 400h 3x in last 90 days and the battery has checked out fine both times. Bottom line is this- the 2006 400h has a small battery under the hood. Although bigger than a motorcycle battery, that's what come to mind when I first saw it. My 2013 450h has a normal sized battery in the rear (and I used it to jump the 2006 this morning). Note: I am not talking about the expensive hybrid batteries under the seat; those serve a different purpose. Lexus put such a small battery under the hood in the 2006 RX 400h that it does not last. My current Lexus dealer has no clue that the 2006 has tiny starter battery in it. I am replacing the 400h battery under the hood even though it checks out fine (a false positive reading). It's 4 years old, and my old dealer agrees with me that the small 400h battery does not last long. Keep in mind the 2006 400h was a vintage year hybrid for Lexus. I think they solved the problem by 2013 in the 450h with a normal sized stater battery next to the spare tire in the rear. They just didn't get it right in 2006 so be prepared to replace the battery (under the hood) more often. Other than that, it's a great car. In addition, unless your Lexus service writer REALLY knows hybrids, they might not have a clue that the battery is is ill suited to last long in your 2006 RX 400h.

11 people found this helpful.

My 2006 Lexus 400RXh has the identical issue as jpsartin. After 10 years, I've only driven 65,000 miles. It's in great condition. Except for the battery. If I don't drive it every other day, it needs to be jumped. And, yes, the battery has been replaced 6 or 7 times now. It is helpful to read that the vintage year of the Lexus RX400h designed the car with a puny battery which does not hold an appropriate charge for starting the car. Had they told me this in the beginning, I would not have spent nearly $70,000 (including finance charges) on the Lexus Lemon. Sorry. It's my opinion. As nice as it was hyped up to be (and the fact I received the coveted Bamboo color in this car) it has turned out to be a big disappointment. I've spent hours and hours driving to and from the dealership, waiting at the dealership, on the phone with the service department troubleshooting issues. The AAA guy who jumped my car a month ago said the battery was at 0%. The dealership could not find any issue. They did not offer to replace my engine battery because "it was not under warranty." I was shown my service records and that it was time for my major tune up. Yes, I shelled out over $900 for this tune up. My AC is still not working, by the way. That will be another, what?, $1000? Three weeks later, the subsequent AAA guy who jumped my car said the battery is dead and is not a good battery. I explained that my service tech said the battery he tested was not under warranty. He went back to the battery and returned to me stating "Oh no, your battery is warranted for 8 years." Really? Seriously? He asked me to recharge it by driving for an hour. Bonus side is that we had Christmas Lights to view. Two weeks later, stopped at the airport to unload a friend's luggage. Kept the back door up. Stayed longer than expected (30 minutes). When pushing the rear door hatch electronic button (this seems it may be a common issue) I was unable to start the car. AGAIN. Really? After sitting for 20 minutes trying to find AAA roadside assistance (which I'm rapidly using up my benefits) I decided to try the car again. Said a quick prayer. The car started. This time I'm driving directly to the dealership. AGAIN My RX400h has been at the dealership for over a week. They have tried to recapture the scenario that I have experienced. They say it's all good and they don't have luck trying to replicate the issue. I am very unhappy. That's putting it at G-rated mildly. So, now I wait to hear the outcome of the latest testing with management supervision. I was sold a lemon. Lemon. Lemon. Why do I need to be told NOW that I need to drive it for at least 15-20 minutes each day to keep the battery in good condition. If I was told that from the beginning, I would have kept my Mercedes Benz 300E which drives beautifully. I bought the AWD for the snow where I moved to. If anyone has any tips on what I can do to replace this car at the dealership's expense since I was never warned about the need to drive constantly, I'm all ears. Thank you.

1 people found this helpful.

my '06 400h ,got it 2 1/2 yrs ago,,just turned 100k miles.had always started fine ,until 3 weeks ago. it needed a chg/jump. The 1 yr old rebuilt batt. we thought, needed to be replaced.Wrong...I got another batt. 2 weeks later same thing .. After disconecting the neg. term, and everything off, key out door sparks every 6- 10 sec.. Something in the elec. sysrem is draining the batt.

6 people found this helpful.

I am having the same problem with my 2006 Lexus 400h. I just put my third battery in, under the hood... what could be causing it to drain the battery... which, by the way is fine, once it got a quick charge....

3 people found this helpful.

Same thing here. 2006 400h now on third battery in the 2 months. First battery was a 7year Lexus battery that was just 1 year old. 2nd battery was 2 weeks old from local parts store. Brought to lexus 2x now and both times they said it was a bad battery. So we had Lexus put in their battery as suggested.....lasted 2 weeks and car dead again. Just had towed to Lexus for them to try again. My bet is that the battery is not being recharged by the converter. These cars do not have alternators.... Could be the invertor/convertor doo-whoppie that recharges the battery is bad. Will let you know what happens

2 people found this helpful.

don't know whether someone has been posted this before, to me I havenot seen such post. feel a necessary to write it down. the day found the battery out of order when I sat in my 2006 rx400h listened radio for half hour, I decided to move chair back to make a little comfort, during the chair movement, suddenly the power went out, radio stopped, then I couldn't start the engineer, got err: "shift to P when starting", so jumped start with help. second day morning, would not start engine, jumped, afternoon it was good to start. third day, same story, so I followed some friend's advice to start the engine, disconnect the 12V battery positive pole connection to see what happen, everything sounded normal without that battery, so I thought the alternator was good to support the engine and car's electricity requirement, after I reconnected the battery, I had three warnings, scary, 1: shift to P when starting 2, check VTC system 3. check hybrid system all of them disappear after I replaced the 12 V battery.

5 people found this helpful.

After having my battery replaced in my 2006 RX 400h, now the key fob, and master switch to the windows will not work, is this because I did put a Lexus battery in it?

1 people found this helpful.

This is the best explanation of how the battery works in our hybrids. This article helped me make an educated decision on buying a new starter battery. Other than the starter battery being replaced over the years (and I live in Florida, which burns thru batteries) and the headlight condensation issue, my RX400h is the BEST car I've ever had. 2006 still going strong.

2 people found this helpful.

I've had identical problems with our 2007 RX400h (which is an otherwise fantastic vehicle). Starter battery dies easily (after kids watching DVD in car for 10 minutes, while packing the car with all doors open for 20 minutes etc. - all of which are not a problem on "normal" cars). My solution was this dandy Red Fuel Portable Jump Starter and Battery Charger, which I picked up two weeks ago. It's already saved us twice, and is a charm to use. $40 at Mallwart. The odd thing is that the car doesn't "turn over" when you jump it, but rather it just clicks on and the 'ready' icon comes on. The engine doesn't even start running for a few seconds afterwards. Which makes me suspect that the problem is not the battery, but something inherent in the electrical system, wherein the jumping process shocks/resets the car into turning on.

1 people found this helpful.

I gave up on my vehicle and bought a new RX. I was never able to solve the battery problem, but still love the Lexus brand.

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