Behaviors Changed After Battery Replaced

[08rx400h]

Hi, All:

I'd like to share this with you, especially Lexus has failed to give me explanations.

On a 2K+ trip in December, the small battery was dead a day before heading home after parked for abour 4 hours. Mine is '08 model with less than 15K miles.

Car was jumped start (Lexus sent a locksmith who can't even locate the battery, to rescue me through AAA, but that's another story), and I made an appointment with the deal right after the car was back home.

The diagnosis was "Battery will not hold load, replace battery to solve", with this replacement on top of 15K service, it took the dealer more than 5 hours to finish. I was given a loaner naturally.

Then, when the car was picked up, I noticed the differences right away. The hybrid system is not working the same anymore. On "Energy Monitor" screen, MPG numbers start jumping all over the place. I always pull out gently by just allowing the battery to work, after the ICE kicked in, the MPG always show above 10, not it shows 3, 5, 7. It used to that when I backed up the gas, the MPG would show 99 right away, not it shows 55; 45; 60, the, eventually 99. On high way, set on cruise control (65 or 70 MPH), MPG numbers changed anyway from 11 to 40MPG, it used to be changed between 23 to 28. The system becomes, let me put it this way, very sensitive.

Brought it back a week after, the dealer arranged a very nice guy claimed to have with Lexus since the beginning to drive with me. We took term driving for about 20 miles and I did my best to explain the differences I discovered. His conclusion was everything seems perfect, but "keep your eyes on the average". My average is 26.5 so far (40% highway), down about 1 mile from before.

Has anyone else here every encourtered this situation? I really would like to know.

[400h08]

Interesting. I understand there is something (don't remember where) in Lexus that can learn your habit of driving over time. May be they have reset the database, and you are back to square one as if you just bought the car.

[katzjamr]

some 400h owners have found that after a dead battery, or after body shop service where they often disconnect the battery for safety and to keep from running down with the doors open, that the dealer has to recalibrate the ISC in the hybrid ECU. as mentioned here already alot of otherwise knowledgable service reps have no idea why that is important, just tell them for your piece of mind to do it. they will get a reading that the system is set correctly or that they need to reset it in either case they can fix it.

some owners were reporting decreased mpg after a battery failure as you are 08rx 400h, and after the system was reset everything returned to normal for them.

i also ran this by my service rep and it was his feeling that any system that needed to be reset would result in a check engine light signal continuously on. at the same time i think some of these things can get out of setting without tripping the check engine light. please keep us posted, dave

[kikogirl]

Yes It happened to me too, and only couple day for it to be normal. It seemed like the gas engine need to run more than normal to charge the new battery.

Hi, All:

I'd like to share this with you, especially Lexus has failed to give me explanations.

On a 2K+ trip in December, the small battery was dead a day before heading home after parked for abour 4 hours. Mine is '08 model with less than 15K miles.

Car was jumped start (Lexus sent a locksmith who can't even locate the battery, to rescue me through AAA, but that's another story), and I made an appointment with the deal right after the car was back home.

The diagnosis was "Battery will not hold load, replace battery to solve", with this replacement on top of 15K service, it took the dealer more than 5 hours to finish. I was given a loaner naturally.

Then, when the car was picked up, I noticed the differences right away. The hybrid system is not working the same anymore. On "Energy Monitor" screen, MPG numbers start jumping all over the place. I always pull out gently by just allowing the battery to work, after the ICE kicked in, the MPG always show above 10, not it shows 3, 5, 7. It used to that when I backed up the gas, the MPG would show 99 right away, not it shows 55; 45; 60, the, eventually 99. On high way, set on cruise control (65 or 70 MPH), MPG numbers changed anyway from 11 to 40MPG, it used to be changed between 23 to 28. The system becomes, let me put it this way, very sensitive.

Brought it back a week after, the dealer arranged a very nice guy claimed to have with Lexus since the beginning to drive with me. We took term driving for about 20 miles and I did my best to explain the differences I discovered. His conclusion was everything seems perfect, but "keep your eyes on the average". My average is 26.5 so far (40% highway), down about 1 mile from before.

Has anyone else here every encourtered this situation? I really would like to know.

[08rx400h]

Thanks for all the responses.

Just came back from 600 Miles trip and found out what kikogirl decribes - ICE runs more than before (battery replaced), therefore MPG is lower. Speed was set at 70MPH most of time and the overall MPG is 23.5 compared to similar trip before, it's 25 (all flat highway, temp around 60 - 70).

Guess I will have to bring up this issue to Lexus again. It really bothers me.

[SOMEONE ELSE'S GOT MY NAME]

Any time you disconect the aux battery you'll reset settings to factory default, so you may notice windows roll up differently, mfd settings / map defaults / seat / mirror adj is funky etc . . . outside of that stuff, there shouldn't be anything different. It may be your mpg's are down simply due to winter temps. That'll always kill averages.

[08rx400h]

Yes, everything has been reset, but, that's what we all expected. It's the Hybrid / ICE engines runs different now (and I got this confirmed by others on this board, it's not my imagination) that concerns me and I live in usually warm (if it's not hot) S. Florida. My previous 2K+ miles to colder states (all below 40), the MPG was about 24 (with 3 passenger and a cargo box on top). I am pretty sure there's some issues here with the system. I will keep you gals / guys updated after I contact with Lexus again.

[jbtex]

Yes, everything has been reset, but, that's what we all expected. It's the Hybrid / ICE engines runs different now (and I got this confirmed by others on this board, it's not my imagination) that concerns me and I live in usually warm (if it's not hot) S. Florida. My previous 2K+ miles to colder states (all below 40), the MPG was about 24 (with 3 passenger and a cargo box on top). I am pretty sure there's some issues here with the system. I will keep you gals / guys updated after I contact with Lexus again.

I replaced the 12v battery on an 08 RX400h - repleaced with Optima 51R. Battery was disconnected during install for about 30 minutes. Other than having to reset windows, sunroof, rear door and some other settings (radio, etc.) there has been no change in the way my car performs - mpg pre and post are the same.

[Gryphon]

I have had around 5-6 dead battery incidents in the two years I have owned my 400h. In some but not all cases I had to reprogram the power windows, power roof, and rear door. Otherwise nothing changed in terms of performance, ICE participation, fuel economy, etc.

Tom

[BillyShaft]

I replaced the 12v battery on an 08 RX400h - repleaced with Optima 51R. Battery was disconnected during install for about 30 minutes. Other than having to reset windows, sunroof, rear door and some other settings (radio, etc.) there has been no change in the way my car performs - mpg pre and post are the same.

I am a huge fan of the Optima batteries since I have a Jeep Rubicon with winch. The Optima will take deep cycling like no other battery out there.

That said, I was wondering how the 51R fit into your RX400? Was it an exact fit and did the terminals line up correctly and all that?

When/if the battery goes out in my RX400, I will definitely go with the Optima.

Thanks in advance!

[jbtex]

I replaced the 12v battery on an 08 RX400h - repleaced with Optima 51R. Battery was disconnected during install for about 30 minutes. Other than having to reset windows, sunroof, rear door and some other settings (radio, etc.) there has been no change in the way my car performs - mpg pre and post are the same.

I am a huge fan of the Optima batteries since I have a Jeep Rubicon with winch. The Optima will take deep cycling like no other battery out there.

That said, I was wondering how the 51R fit into your RX400? Was it an exact fit and did the terminals line up correctly and all that?

When/if the battery goes out in my RX400, I will definitely go with the Optima.

Thanks in advance!

Exact fit - even the Lexus plastic battery frame fits. 51R has the correct postioning of the terminals.

[BillyShaft]

Exact fit - even the Lexus plastic battery frame fits. 51R has the correct postioning of the terminals.

Awesome news! Thanks!

BTW, I always get my Optima batteries from Costco. Their return policies cannot be beat.

[jbtex]

Exact fit - even the Lexus plastic battery frame fits. 51R has the correct postioning of the terminals.

Awesome news! Thanks!

BTW, I always get my Optima batteries from Costco. Their return policies cannot be beat.

51R is probably not a commonly stocked size - had to order on-line from Batteries Plus.

[dadcat]

Yes, everything has been reset, but, that's what we all expected. It's the Hybrid / ICE engines runs different now (and I got this confirmed by others on this board, it's not my imagination) that concerns me and I live in usually warm (if it's not hot) S. Florida. My previous 2K+ miles to colder states (all below 40), the MPG was about 24 (with 3 passenger and a cargo box on top). I am pretty sure there's some issues here with the system. I will keep you gals / guys updated after I contact with Lexus again.

The following link has the TSB to perform whenever the battery is disconnected. As katzjamr said, it involves the ISC (idle speed control) learning. Some of the possible symptoms of not performing the ISC learning procedure include engine runs too long or more frequently than normal and reduced fuel economy.

http://autozone.kiev.ua/files/Lexus%20400H/Battery/data.pdf

[skyfish400h]

The following link has the TSB to perform whenever the battery is disconnected.

http://autozone.kiev.ua/files/Lexus%20400H/Battery/data.pdf

Thanks for posting this. And thanks to Autozone for making it available.

I believe you can do this on the '06 version of the NAV without needing the special equipment list. The "secret access code" to the DIAGNOSTICS screen is posted on here somewhere.

I think it was INFO, VOLUME, upper left, upper right, upper left, upper right... until the secret screen comes up with OVERRIDE on it so's you can disable the nagging "I agree" button and use the NAV at any speed.

But once you are in this secret screen, you should be able to find the submenus mentioned in the TSB and answer the question "is our cars learning?"... he he he. (God, I"m glad he's gone...).

[silvercorvette]

I have had around 5-6 dead battery incidents in the two years I have owned my 400h. In some but not all cases I had to reprogram the power windows, power roof, and rear door. Otherwise nothing changed in terms of performance, ICE participation, fuel economy, etc.

Tom

I probably had more than that, I am in the habit of rolling down the windows and listen to the radio while I work in the garage but the 400H has an undersized battery. I traded the 400H for a 450H and it has a bigger batter which is located in the trunk. The battery in the GS450H did go dead right after I got the car but it was due to a defective battery. The battery was replaced back in July or Aug of 08 and I haven't had a problem since even though the car sits in the driveway for a week or longer. To give you an idea how little I use the car. I got the car mid June of 08, the car has made 4 (nine hundred mile each way) round trips between SC an NY plus a few one hundred mile trips between Long Island and Stamford CT which total somewhere around 4,000 miles. I hace a little over 5,000 miles on the car since June so between June and now I have only put on a bit over 1,000 miles on the car. If I only put on about 150 miles a month the car sits in the drive way a lot but even with such little usage the batter does not run down after sitting for a week or more without being used

[Gryphon]

Yes, everything has been reset, but, that's what we all expected. It's the Hybrid / ICE engines runs different now (and I got this confirmed by others on this board, it's not my imagination) that concerns me and I live in usually warm (if it's not hot) S. Florida. My previous 2K+ miles to colder states (all below 40), the MPG was about 24 (with 3 passenger and a cargo box on top). I am pretty sure there's some issues here with the system. I will keep you gals / guys updated after I contact with Lexus again.

The following link has the TSB to perform whenever the battery is disconnected. As katzjamr said, it involves the ISC (idle speed control) learning. Some of the possible symptoms of not performing the ISC learning procedure include engine runs too long or more frequently than normal and reduced fuel economy.

http://autozone.kiev.ua/files/Lexus%20400H/Battery/data.pdf

My service manager, who quite likely could be either wrong or lazy, says that this only applies to 2006 models but not 2007 on.

Tom

[skyfish400h]

I believe you can do this on the '06 version of the NAV without needing the special equipment list. The "secret access code" to the DIAGNOSTICS screen is posted on here somewhere.

I think it was INFO, VOLUME, upper left, upper right, upper left, upper right... until the secret screen comes up with OVERRIDE on it so's you can disable the nagging "I agree" button and use the NAV at any speed.

Nope.

No DIAGNOSTICS buttons on the secret screen.

And its MENU, VOLUME, upper left, lower left, upper left, lower left to get to the screen.

[riwyle]

My service manager, who quite likely could be either wrong or lazy, says that this only applies to 2006 models but not 2007 on.

Tom

I do not know for sure, but since this TIB is dated early 2006, I would be very surprised if Lexus did not, in subsequent model years, fix this glitch . It would not be difficult to do and it would not make sense not to.

[SOMEONE ELSE'S GOT MY NAME]

I believe you can do this on the '06 version of the NAV without needing the special equipment list. The "secret access code" to the DIAGNOSTICS screen is posted on here somewhere.

I think it was INFO, VOLUME, upper left, upper right, upper left, upper right... until the secret screen comes up with OVERRIDE on it so's you can disable the nagging "I agree" button and use the NAV at any speed.

Nope.

No DIAGNOSTICS buttons on the secret screen.

And its MENU, VOLUME, upper left, lower left, upper left, lower left to get to the screen.

. . . and this only works if your NAV DVD version is older than rev 6.1 ... unless you hack your disk with a new loading file.