400h 12v Battery Questions

[jim_w]

I have browsed the hypbrid forum's search results on 'battery' and found lots of useful information, though some of it seems contradictory (or just confusing to me). I have decided to start a new thread with a summary of what I think I have learned. Hopefully some of you experts out there will verify and/or correct this note.

Background:

Like many others, I have had problems with the 12V battery in the 400h. Like a few others, my first time was the day I left the dealer. Sitting in the car in my driveway, enjoying playing with the wealth of niftyfeatures on the dashboard, plus the power moonroof and probaby the power rear door, suddenly the dash lights blinked and went dark, and I ended up unable to start the car! Normally, I figure if the interior lights are bright, and the horn honks, and for this model, the steering wheel extends when I insert the key, the battery must be okay. Not true! Even the dash lights would come back on when I reintroduced the key, but turning the key to START would not light the READY light, and hence, NO GO! (Happily, the dealer sent out a technician who jump started the car.)

After reading many threads in these informaiton rich forums, my understanding is that the traction battery recharges the 12v battery, rather than an alternator powered by the gas engine. Does this only happen when the key is inserted? Does this only happen in certain key positions?

The technician who came out to jump start the car told me that the gas engine charges the 12v. He also told me that the 12v starts the gas engine as well as handles all the usual 12v features of regular, non-hybrid cars. This seemed rather odd to me - sort of a Catch 22, at least for a hybrid where there is a wealth of charged up electrical power. However the fact that he jump started the car with a 12v jumper battery connected to the 12v 400h battery gave me reason to believe him.

So, is my learning correct (see bold text above)? Or is the technician right? Or is it something in between???

Even if I have learned correctly from these forum threads, I remain baffled by a system that can have plenty of traction battery power to drive the car but still have insufficient 12v power to turn on the READY light so I can actually drive it. The role that the 12v battery plays in this seems misplaced, but maybe that is just my engineering mind working overtime...

Perhaps if I had left the car overnight, in the morning the slow charging of the 12v from the traction battery would allow me to drive my 400h again without a jump?

Thanks in advance for any clarity and advise!

[williz]

I have browsed the hypbrid forum's search results on 'battery' and found lots of useful information, though some of it seems contradictory (or just confusing to me). I have decided to start a new thread with a summary of what I think I have learned. Hopefully some of you experts out there will verify and/or correct this note.

Background:

Like many others, I have had problems with the 12V battery in the 400h. Like a few others, my first time was the day I left the dealer. Sitting in the car in my driveway, enjoying playing with the wealth of niftyfeatures on the dashboard, plus the power moonroof and probaby the power rear door, suddenly the dash lights blinked and went dark, and I ended up unable to start the car! Normally, I figure if the interior lights are bright, and the horn honks, and for this model, the steering wheel extends when I insert the key, the battery must be okay. Not true! Even the dash lights would come back on when I reintroduced the key, but turning the key to START would not light the READY light, and hence, NO GO! (Happily, the dealer sent out a technician who jump started the car.)

After reading many threads in these informaiton rich forums, my understanding is that the traction battery recharges the 12v battery, rather than an alternator powered by the gas engine. Does this only happen when the key is inserted? Does this only happen in certain key positions?

12V battery is charged if the car shows "READY". charging is done from inverter and the high voltage battery.

if the voltage from the 12V battery is below 10,5V it will not be powering up the computer systems and you will not see the "Ready".

if the ignition switch is in "radio" or "drive" position depending on what is switched on (lights, radio, air condition, ect.) there will be between 10 and 40 amps drawn from the 12V battery and depending on the charge condition battery voltage will fall under 10,5 volts in 10 to 45 minutes (battery has a capacity of 45Ah and is very small for this car).

and yes, in many cases it is helping to switch all and every thing off (lights, radio, air condition, seat heating.....) and take off the ignition key and wait for some minutes (5 to 20 minutes is normally enough) and try to start again. very often ready is then coming up because the starting up is not taking many current (there is no engine cranking like in other cars).

[SOMEONE ELSE'S GOT MY NAME]

Welcom Jim w,

After 3 years, we (meaning "she who must be obeyed") finally got stung by the 12v battery issue. We (she) just happened to be using the 400h as an open air market ... supplying info from a parking lot, handing out info flyers, and after several hours with dome lights & the radio on, no start. Only a block away, I brought over a 12v spare (out of our electric party boat) and it started right up. She doesn't remember me telling her to always make sure the dome light is off and/or that the rear hatch is closed (until she found a note from long ago), after several close calls. anyway it's working now and I'm guessing that in 1 1/2 years it'll be time to replace it anyway. We'll be replacing it with a battery that actually was designed to have 'cranking amps' so the issue will no longer exist.

I suppose the ICE does 'run' the 12v auxiliary battery in a remote sense, because the ICE supplies regenerative power to the traction pack, which then supplies the auxiliary. But yea, it doesn't sound like the tech was talking about that. It only took us about 20 minutes with the traction pack on for the auxilary battery to be fine.

[jbtex]

Welcom Jim w,

After 3 years, we (meaning "she who must be obeyed") finally got stung by the 12v battery issue. We (she) just happened to be using the 400h as an open air market ... supplying info from a parking lot, handing out info flyers, and after several hours with dome lights & the radio on, no start. Only a block away, I brought over a 12v spare (out of our electric party boat) and it started right up. She doesn't remember me telling her to always make sure the dome light is off and/or that the rear hatch is closed (until she found a note from long ago), after several close calls. anyway it's working now and I'm guessing that in 1 1/2 years it'll be time to replace it anyway. We'll be replacing it with a battery that actually was designed to have 'cranking amps' so the issue will no longer exist.

I suppose the ICE does 'run' the 12v auxiliary battery in a remote sense, because the ICE supplies regenerative power to the traction pack, which then supplies the auxiliary. But yea, it doesn't sound like the tech was talking about that. It only took us about 20 minutes with the traction pack on for the auxilary battery to be fine.

Optima makes a Yellow Top (I think 51R) that is a direct replacement.

[katzjamr]

i considered the yellow top, its even sold at costco but at three times the cost of a costco battery, and with only a one year guarantee vs the other batteries three years no questions asked, and a longer prorated warranty after, that i thot id go with the costco one.

[Barefoot Bob]

i considered the yellow top, its even sold at costco but at three times the cost of a costco battery, and with only a one year guarantee vs the other batteries three years no questions asked, and a longer prorated warranty after, that i thot id go with the costco one.

I sell battries at my shop and Interstate is the only way to go

[jim_w]

Welcom Jim w,

After 3 years, we (meaning "she who must be obeyed") finally got stung by the 12v battery issue. We (she) just happened to be using the 400h as an open air market ... supplying info from a parking lot, handing out info flyers, and after several hours with dome lights & the radio on, no start. Only a block away, I brought over a 12v spare (out of our electric party boat) and it started right up. She doesn't remember me telling her to always make sure the dome light is off and/or that the rear hatch is closed (until she found a note from long ago), after several close calls. anyway it's working now and I'm guessing that in 1 1/2 years it'll be time to replace it anyway. We'll be replacing it with a battery that actually was designed to have 'cranking amps' so the issue will no longer exist.

I suppose the ICE does 'run' the 12v auxiliary battery in a remote sense, because the ICE supplies regenerative power to the traction pack, which then supplies the auxiliary. But yea, it doesn't sound like the tech was talking about that. It only took us about 20 minutes with the traction pack on for the auxilary battery to be fine.

Thanks for the many responses!

Quick question: You say: "It only took us about 20 minutes with the traction pack on for the auxilary battery to be fine."

For the traction pack to be "on" what position does the key need to be in? OR, is the system able to boost the 12v battery back up to 10.5v without my needing to leave the key in the car (and stay there with it)?

[riwyle]

Welcom Jim w,

After 3 years, we (meaning "she who must be obeyed") finally got stung by the 12v battery issue. We (she) just happened to be using the 400h as an open air market ... supplying info from a parking lot, handing out info flyers, and after several hours with dome lights & the radio on, no start. Only a block away, I brought over a 12v spare (out of our electric party boat) and it started right up. She doesn't remember me telling her to always make sure the dome light is off and/or that the rear hatch is closed (until she found a note from long ago), after several close calls. anyway it's working now and I'm guessing that in 1 1/2 years it'll be time to replace it anyway. We'll be replacing it with a battery that actually was designed to have 'cranking amps' so the issue will no longer exist.

I suppose the ICE does 'run' the 12v auxiliary battery in a remote sense, because the ICE supplies regenerative power to the traction pack, which then supplies the auxiliary. But yea, it doesn't sound like the tech was talking about that. It only took us about 20 minutes with the traction pack on for the auxilary battery to be fine.

Thanks for the many responses!

Quick question: You say: "It only took us about 20 minutes with the traction pack on for the auxilary battery to be fine."

For the traction pack to be "on" what position does the key need to be in? OR, is the system able to boost the 12v battery back up to 10.5v without my needing to leave the key in the car (and stay there with it)?

Only when the "READY" light is lit is the traction battery "on". This is for safety of emergency responders and others as well as some operational reasons.

[riwyle]

You may find this link interesting as it shows a one-line wiring diagram of the high voltage system. Notice the n.o. relay contacts in the power lines from the traction (HV) battery. (pg 14) The 12v relay coil to close these contacts and place the HV battery in service is energized by the 12v battery. Therefore, if you have drawn down the 12v battery, you cannot close these contacts and therefore cannot charge a low battery with the HV battery without a jumper from another battery or charging the battery by other means.

http://www.lexus.ca/images/designtechnology/RX400hERG-e.pdf

[HybridDon]

I have had my auxiliary battery replaced twice in my 2006 RX400h at about a 2 year interval. Before replacing it, I tried to charge it myself, but it would only charge for 10 minutes on the charger, then the charger indicated a charged state, and then the battery would die soon after that. I had to reset the windows, seats, and navigation computer too.

Both times, the dealer tested the battery and said that the battery did not pass the load test and needed to be replaced. The battery is rated for 84 months and when you replace the battery, it is suppose to be prorated, but their idea of prorating is that it is covered 100% for the first 2 years and then only 50% after that. They charged me $145 to replace it a second time because my battery was 2 years and 9 months old. I think that this is outrageous especially considering that I was stranded and because this is an expensive car. It is too bad that Lexus will not just admit that this is a bad design and fix it. I think there should be a recall and a fix for this because it really becomes a safety issue if people are being stranded in places that are unsafe (from weather or criminals).

[RX400h]

Mmmmm, our RX400h has its original battery and it is now 5 years and 3 months old. It starts the car like it is brand new. I suspect those who have batteries that fail early were unlucky. Most Toyota batteries last well over 5 years from what I've seen.

The Costco Kirkland battery is an excellent battery, especially for the very low cost.

[katzjamr]

There is no doubt the oem battery is small on the 400h and does not have alot of reserve, mine would not hold a charge after three years, and i drive mostly on the freeway. Like the previous poster i went to costco, their battery that is the same size replacement for our 400h has more power, and i believe they will give you a new battery at any point in the three year warranty, not prorated. it was $59.oo and i installed it myself. remember, when you disconnect the battery for any reason, the dealer has to reset the icu ( i hope i have the term correct) or your mpg will suffer.

[vinovelo]

There is no doubt the oem battery is small on the 400h and does not have alot of reserve, mine would not hold a charge after three years, and i drive mostly on the freeway. Like the previous poster i went to costco, their battery that is the same size replacement for our 400h has more power, and i believe they will give you a new battery at any point in the three year warranty, not prorated. it was $59.oo and i installed it myself. remember, when you disconnect the battery for any reason, the dealer has to reset the icu ( i hope i have the term correct) or your mpg will suffer.

Is there a way for the owner to reset the ICU?

/Steve

[Jim Nazium]

There is no doubt the oem battery is small on the 400h and does not have alot of reserve, mine would not hold a charge after three years, and i drive mostly on the freeway. Like the previous poster i went to costco, their battery that is the same size replacement for our 400h has more power, and i believe they will give you a new battery at any point in the three year warranty, not prorated. it was $59.oo and i installed it myself. remember, when you disconnect the battery for any reason, the dealer has to reset the icu ( i hope i have the term correct) or your mpg will suffer.

Is there a way for the owner to reset the ICU?

/Steve

Yep! Here you go...

ISC learning procedure

Cheers,

MadloR

[RX400h]

Uh oh, it looks like you'll need a Diagnostic Test Kit and a CAN Interface Module Kit to do the relearn procedure.

[riwyle]

Uh oh, it looks like you'll need a Diagnostic Test Kit and a CAN Interface Module Kit to do the relearn procedure.

I have seen on this or another site a procedure to follow which doesn't require the test equipment. I have no idea if it works. Someone else may have a reference to the info.

Also, although the TSIB does mention possible reduction in fuel economy if not programmed for optimal idle speed, unless you have many cold starts each day I sure don't see more than a very minuscule change in fuel use. How often is the ICE idling when warm in a hybrid car? It is either off or at higher speed helping to propel the car. In neither case is the ISC in the loop.

[lemon]

Uh oh, it looks like you'll need a Diagnostic Test Kit and a CAN Interface Module Kit to do the relearn procedure.

No you don't. That link is for the Lexus TSB, just to explain that the ISC reset needs to be done.

This link explains how to do it without hooking up the Lexus computer (I've done it and it works - trust me)

http://us.lexusownersclub.com/forums/index.php?showtopic=58930

[lemon]

Uh oh, it looks like you'll need a Diagnostic Test Kit and a CAN Interface Module Kit to do the relearn procedure.

I have seen on this or another site a procedure to follow which doesn't require the test equipment. I have no idea if it works. Someone else may have a reference to the info.

Also, although the TSIB does mention possible reduction in fuel economy if not programmed for optimal idle speed, unless you have many cold starts each day I sure don't see more than a very minuscule change in fuel use. How often is the ICE idling when warm in a hybrid car? It is either off or at higher speed helping to propel the car. In neither case is the ISC in the loop.

It actually made about 2 l/100km difference for me when I did it (from 10 l/100km to 8 l/100km per the vehicle trip computer). One thing I found prior to doing the reset was that it was very hard to keep the vehicle in electric mode, no matter how light on the throttle. After doing the reset, it was much easier with a light throttle application to accelerate and cruise in electric mode only.

You ask "How often is the ICE idling when warm in a hybrid car?" That's just it - it shouldn't idle much when the ICE is warmed up. Prior to doing the reset, I found the vehicle idled quite often, even when stopped and fully warmed up. That went away after doing the reset. There's a reason it's called the IDLE speed control. The transmission clatter that is mentioned in the TSB was also reduced (I noticed that clatter on the very first cold start of the day (almost like some switch in the tranny was turning on and off).

As the TSB states, the following may occur if the ISC reset is not done:

Engine runs too long or more frequently than normal

Reduced fuel economy

Transmission gear “clatter” noise at idle is more pronounced

[Jim Nazium]

I have had my auxiliary battery replaced twice in my 2006 RX400h at about a 2 year interval. Before replacing it, I tried to charge it myself, but it would only charge for 10 minutes on the charger, then the charger indicated a charged state, and then the battery would die soon after that. I had to reset the windows, seats, and navigation computer too.

Both times, the dealer tested the battery and said that the battery did not pass the load test and needed to be replaced. The battery is rated for 84 months and when you replace the battery, it is suppose to be prorated, but their idea of prorating is that it is covered 100% for the first 2 years and then only 50% after that. They charged me $145 to replace it a second time because my battery was 2 years and 9 months old. I think that this is outrageous especially considering that I was stranded and because this is an expensive car. It is too bad that Lexus will not just admit that this is a bad design and fix it. I think there should be a recall and a fix for this because it really becomes a safety issue if people are being stranded in places that are unsafe (from weather or criminals).

The "auxiliary" battery is warrantied for 48 months (I am assuming you made a typo), not 84 months. Mine died two days ago (well, not true, it was dieing all the time in the 50 months or so of ownership. I complained at every service interval, and was told "oh, it's normal, alot of hybrid customers complain about this"). Anyhoot, two months out of warranty, and the dealer wanted $250 for the factory battery (with a 1 year warranty replacement warranty).

I said, thanks, but no thanks. I went to a popular auto parts store, and found there "house brand" battery (they only had one choice) for about a $100 bucks or so. The battery came with a 3 year replacement warranty, and an additional 6 years pro-rated warranty. At time of purchase, they offered a $9.99 insurance plan, which converted the additional 6 years pro-rated warranty into an additional 6 years replacement warranty. Can't argue with that.

There is no way I was going to shell out for an Optima spiral type battery, given the outrageous cost and very marginal warranty (as well as, good luck finding someone local to actually honor the warranty). Imagine, having to pay freight to ship the battery back to Optima for a warranty claim?

Cheers,

MadloR