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Rx400H 12V Battery Voltage As Measured = ?


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Recently bought a 2008 RX400h that is 3 years old with 18,000 miles. I had it trucked to me from a Lexus dealer who had been storing it for a couple of weeks in their basement.

The car would not start when the truck arrived at my house. It had to be "jumped". I then charged the battery (the 12V mini-battery) and it again would not start the next day w/o a jump. It did this a total of 3 times in the first day we had it. After each jump, I charged the battery. It came up to charge quickly...an hour or two.

It has been over a month now and the start failure has not repeated.

I recently bought a Solar battery tester and just tested the battery. It reads 12.01 V (consistently, engine off) and 270 CCA. I don't know what the CCA is suuposed to be (no label on battery), but 270 CCA seems low and so does 12.01V. I tested two other batteries I have on my bench (big sealed gel batteries for BMW and MB), one 9 years old and one brand new and both read 12.45 V and >>600 CCA.

I am going to have a Lexus shop check the battery in two weeks. I was curious, however, what voltage reading is normal for an RX400h 12V battery with engine off. Anyone know?

Thanks.

- nopcbs

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The 12V battery in my '08 "went" at 3.5 years and ~25K miles. It had dropped in voltage to high 11V. I had to "jump it" 2 times and when I took it to the dealer, they said it was somewhat unusual for one to go bad that soon, but not unheard of. They also said the electrical system really needs to "see" 12.5V or better to operate properly.

FYI, my vehicle is parked outside and not driven every day. That may have something to do with it.

Imagine my delight when I picked it up and there was NO CHARGE because it was still under warranty.

Sounds to me like yours is failing. My recommendation is to get a new battery if Lexus determines it's "on the way out."

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Do yourself a favor, just replace the battery...Coscto, Sams club, or Walmart...and be done with it. The Original equipment batteries had a terrible reputation for reliability....

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You can revive the battery with a good charger, but your best option is to replace it now.

Been there, done that. When I first got it I had to jump start it three times and charged the battery after each jump...with an excellent charger. It was on intermittant charge after an hour each time. The battery is definitely bad and I am going to get it replaced under warranty. There is some argument in favor of just buying an Advance battery for $85, but there is a principle here. Toyota should not put crummy batteries in a $50,000 vehicle and I do not intend to subsidize bad decisions..

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Make sure you tell the dealer to perform the ISC reset of replacing the battery. Be very specific and firm with them - it HAS to be done if the battery is replaced or run down below 7.2 volts. There is a TSB regarding this. If the dealer plays dumb (or just plain is, as is unfortunately the case a lot of times) print a copy of the TSB from here and hand it to them. You'd be surprised at how many dealers don't know about the ISC reset.

***edit*** Better yet - print a copy from here (there are three pages)

http://us.lexusowner...l=&fromsearch=1

and just take it with you when they replace the battery and ask them to do it.

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  • 2 weeks later...

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