Had a dead 12 volt battery twice after 4 day stay at airport p-lots. A quick jump got it going. Lexus says they don't know why and that they haven't heard of other 400h's having same problem.

Saw a post about the auto light having to be shut off. Does anyone know anything about this?

JIM

 

bring it to the dealership. i havent heard or seen anything like that go wrong. but i have seen bad cells in the hv pack. maybe u leave soemthing on. but ur best bet is to take it to the dealership to have it fixed

 

I think he's talking about the 12V battery.

Well, the precautionary measure is to turn everything to the OFF position.. so that includes the headlights, visor lights (if there's a switch) just to minimise drain on the battery, that's all.

 

I was referring to the 12 volt. How much drain occurs from the auto head light mode? What else could I do to minimize the drain?

JIM

 

I'm not actually sure, I've never measured. I'm not that familiar with the RX's tiny details since I've only test driven it once and didn't have time to take note.

On my Prius, if I were to leave it parked for a while, I'd also turn off my dome lights to the OFF position, and the same goes for my vanity mirror lights and my cargo light, all of which have switches to turn them off. We also have the option of turning off our Smart Key System (which, surprisingly, the other Toyota/Lexus cars don't have). This way, the car won't send out signals, searching for the smart key.

Speaking of which, make sure your smart key isn't too close to the car when you're at home. I don't remember the exact distance off the top of my head but if it's closer than said distance, the car and key will be in constant communications. I know this will drain the key's battery and it *may* drain the 12V too.

You're not alone, since I've also experienced a dead 12V battery before back in January 2005 but it has never happened again and I never found out why.

 

As previously recommended, have the dealer check out the charging system and the 12 volt battery. They are the only ones trained on the hybrid systems.

 

Anyone have any recent experiences with this?

Our 400h for some reason seems to be having a dying 12 volt for some reason. It was fine for a week but then again this morning the car wouldn't start. I jumped it and drove it around a bit. Noticed that the engine kept running even at low speeds. Debating whether to remove that battery and have it charged somewhere or to call the dealer. Seems weird though, the 12 volt is only 3 years old.

 

To the two posters with dead 12 volt batteries. What year are your vehicles?

To the last poster - if your RX is a 2006, you have to do the "ISC learning procedure" if the battery is removed, or drops below 7 volts. Lexus has a TSB regarding this. If it's not done, you'll find the ICE runs more often, you'll hear clunking from the tranny when idling, and you'll go bald.

See here - http://us.lexusownersclub.com/forums...howtopic=58930


I just replaced my 12 volt battery (2006 model, on the road in April 2005), so my 12 volt lasted about 5 years, which seems to be in the normal range for a wet cell 12 volt.

Good thread here - http://us.lexusownersclub.com/forums...howtopic=59673

In my case, the battery wasn't leaving me stranded, but I did leave the ignition on, but not in READY mode for about 5 mins while I was tinkering with something, and the battery didn't have enough power to start the computers (the 12 volt does not turn a starter motor like in a normal car, just powers the computers and runs the accessories). So I decided that wasn't enough reserve power for my liking. Took it in to get it tested, and while it had 12 volts, the CCA amps were down to 200 or so, and they're supposed to be 450. Now, as I said, the Cold Cranking Amps mean nothing for us, because the battery doesn't do any cranking, however, the fact that they were low indicated the battery was obviously on it's way out.

By the way, I put another wet cell (traditional 12 volt battery), but I'll be replacing it with an Optima yellow top deep cycle, just because I can get one way way below cost.

 

We brought our newly-purchased cpo 2007 rx400h home from the dealer last July, and within a couple weeks the battery had failed to start [er, "Ready"] the car 4 times. Dealer replaced the battery.

 

Its very simple, have the battery load tested. The 400h seems to have more of a draw on the battery than other vehicles. They even tell you to start it every so often if you leave it undriven for awhile. So if you battery is not in good shape you will have this problem. Also the battery on the 400h is very small not only in CCA but also in reserve due to it not needing to start the engine.

 

the battery in our 2006 has been dying often..
so we just got a new battery from costco. $59.99 (same specs/warranty as the $85 one at autozone)

the car "feels" faster now, too

this sounds REALLY dumb.. but i am thinking about doing the following to save the 12v battery.. (i figure since the 12v doesn't "recharge" as much, this MIGHT help):

1. turn off the DRL those bulbs run at what? 25w or so, FULL TIME
2. LED fog lights. 5w vs 55w (at night only)
3. LED interior lights 2w vs 1w? (i probably WON'T do this one)

 

I think it's more the draw on the batteries when the car is off that you need to worry about (and there's probably nothing you can about these draws). When the car is off, power is still needed to keep computer memory, clocks etc. For some reason this power off draw seems to be higher on the 400h (or maybe as someone mentioned, it's just the fact that the D51R battery is just too small (most have a reserve capacity around 50-70mins) and perhaps the fact that it's not a deep cycle battery. The constant charging and discharging causes the regular wet cell battery to die sooner. Too late for you now, but you might have considered a deep cycle battery like a yellow top Optima as a replacement.

When the car is running, the 12 volt battery will be charging to make up for powering the DRLs, fogs, radio etc. etc. so changing those probably won't do anything. Mind you, it won't be charging via an alternator since we don't have one. Instead (if I remember correctly) it charges via the traction battery (which of course charges via MG1 via the engine). Complicated, no?

 

damn.. should've gotten the 350..

 

If your 400h is a 2006, don't forget that the ISC learning procedure has to be done when you replace, disconnect or run the battery below 7 volts.

 

My 2006 battery lasted about 3.5 years. I live in Florida so that's considered pretty normal with the heat here. Lexus replaced it a competitive price vs local shops.