RGSW

I had Lexus replace my 12V battery in my 2022 RX450h as I could not get the door to unlock. Also the manual key would not trigger the driver's door. The dealer charged the battery (only 18 months old) and it tested "Dead Cell" and they replaced it under warranty. Later, I fixed the driver's door manual key release with some WD-40, it now works as it should have when the battery died.

jrobe

I have never had any clear warning that a battery is going to fail. It usually just finally gives you the "click- no start" sign when you try to start it the next time. The shop probably ran it pretty low with whatever they did and that was the final straw. I wouldn't blame them though for this. Frankly, if there is any blame it would be not knowing that your battery was 8 years old till now. Luckily it didn't die in the middle of nowhere a long way from home. I have had that happen when I didn't stay on top of my maintenance.

chuyrobles

I find it bizarre Goodyear sid not load-test the battery. They would have only checked the voltage with a volt meter. It is very possible it shows 12 volts, but put a load on it and the voltage will drop. It could also be that your starter is kaput. That’s why one would load-test the battery. If it shows good, you move on to the starter or a bad connection.

AA2016

Do you happen to have a dash cam installed? My battery also recently went out after it was in the shop for some work and I thought it was suspicious as well, but after viewing the footage, I saw how the camera would turn on abruptly due to the motion detection feature while the car was off. My battery was 3.5 years old so it was on its way out and the excess drain caused by my dash cam pushed it to failure.

jeff32113

They claim to have a new type of "digital" test that "calculates" battery condition without a traditional load test. True? BS? I have no idea.

jeff32113

A reasonable hypothesis but I don't have a dash cam.

jeff32113

Regarding ONLY the 4th Gen RX (2016-2022), if the battery is disconnected for an extended period of time, say longer than 10 minutes, are any CRITICAL SETTINGS (i.e., settings that effect the engine or other critical systems) lost in the computer? I don't care about trivial settings like clock time, mirror positions, and the like. Why is this not a simple, straightforward, black and white issue? I don't know a lot about cars. I do know a lot about computers and electronics so I can't comprehend why, in the automotive world, an issue that should be straightforward and completely predictable has 10,000 differing opinions.

Browsing through forums on this issue I see everything ranging from "I just dropped in a new battery old school and had no problems" to "you absolutely most maintain some power to the car's computer during the battery swap or unpredictable results will follow because some important settings will be lost". So far nobody has advised waving dried chicken bones over the computer to ward off evil spirits, but I still expect to see that at some point.

Please don't merge this into the other DIY battery thread, that thread has so much conflicting and off-topic material it's impossible to glean anything useful from it.

Thanks! Responses from folks that know the answer to this question with confidence (as opposed to speculation lol) ARE HUGELY APPRECIATED!

ravenuer

I'd go with BS.

15RX98422

when Lexus changed my battery last year on my 2015 RX F, it did come back with lost settings in my Nav. I did watch a Youtube video, where the mechanic used a portable charger/jumper and piggybacked to the battery leads. That way, the car never lost power. Most mechanics will not spend the time to do this, I believe.

jeff32113

Thanks for taking the time to reply but you are in the 4th gen (2016 and later) forum, I don't think your 2015 3rd gen computer behaves the same way as my 2016. I live in an area with no great service options and anyway the techs working on batteries are usually the least experienced and least knowledgeable so I am trying to understand the worst case scenario where a careless tech leaves my car with no power for some extended period of time.

coolbrazz

I agree with your concerns about losing critical settings. Have you tried calling a Lexus Service Dept and ask them. I've done this with my 2015 Chevrolet and daughter's 2022 Hyundai with questions and received helpful answers from both dealers. I even ordered the recommended part from them. You will receive many opinions on a forum just like an Amazon review with hundreds to choose from.

I never replaced my battery in any of the Lexus vehicles I've owned, but replaced in my other cars with tech in them. All these cars have computers in them and just like any computer they all have a backup power source to protect critical settings. I had them disconnected for 1-2 minutes, how long in your year and model I have no idea.

Lex2000TL

According to Toyota/Lexus mechanic, all latest generations of Toyota/Lexus (quite possible this applies to just any modern car as well) learn you driving stile to adjust transmission shifts accordingly. Disconnecting car battery for extended period of time will reset this to factory original setting.

coolbrazz

A bad cell in a battery isn't easy to find. When you test the voltage with engine off and then while running. Your voltage may be in an acceptable range. The only warning you get with that is sometimes it won't crank. A weak battery will start slow, lights will dim and key fob won't always work along with other strange issues. Normally a charge can squeeze a little more life out of it before it becomes too unreliable.



As for the oil question, it should throw a code or the oil light will come on if something is seriously wrong. If they used the wrong oil or filter you may not know for sure unless you changed it yourself or car will let you know by codes and gauges.

When I don't have time to change my oil, I'll bring it with me with filter. Brand names are very reasonable at Walmart.

jrobe

If I insisted on advice only from qualified automotive experts who are sure of the technical answer, I probably wouldn't ask it on an internet forum.

jeff32113

Not how I phrased it but sorry you took such offense.