Lexus 12v battery issue - any satisfactory resolution?
If I leave the windows down overnight (car is in garage) does that cause any of the systems to fail to fall asleep? I've read some info that it does, and some that it doesn't. Any thoughts or facts on this matter?
BTW, I did get the car back. I hooked up my Multimeter and the battery was at like 12.3 and dropped to about 12.1, then held steady. I know the system was active as I had the hatch open and a few minutes before had the car running.
When the car was on\READY, the MM jumped up to just over 14V indicating the battery was being charged properly.
But the "open window" will be a thing as my wife does like to keep the windows down in certain temps, and it will get parked in the garage with the windows down....unless I give ten or fifteen reminders to NOT do that.
But if it has no effect on the car's system, she can continue her habits.
Thanks.
Last edited by DaveinPA; Apr 19, 2026 at 09:07 AM.
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https://presale.alwaystart.com/
Anybody going to try one?
https://presale.alwaystart.com/
Anybody going to try one?
I already have the Ionic Emergency Start so habe no need for another solution.
So, I clamped the amp-clamp onto the positive battery terminal, then using a $20 TAPO camera set to record 24\7, I videoed the milliamp draw under certain "Actions".
Just after closing the hatch at 9:35, the system was drawing 3,360 Milliamps or 3.36amps. "Normal" from what I've researched is 30 to 60 milliamps. So, it took the car about 26 minutes to go from the draw of 3,360 MI to 50 MI....or what should be normal.
Now, at 10:17, the system suddenly drew 450 MA. I did nothing to make this occur. But one minute later the system went back to 50 MA. At 10:45 I went to my kitchen, retrieved the FOB and went to the car to just open and close the door. As you can see the system then drew 3,690 MA. I then shut the door, and went to the Laundry room placing the key where I usually place them for 20 years. As you can see it took the car about 20 minutes to shut down (or put to sleep) the systems that awoke when I opened the door. That was a bit shorter than the first time of 26 minutes when I took the FOB "far away" to my kitchen.
At 11:19 I then moved the FOB from the dryer to the kitchen....farther away....and nothing significant occurred.
So, it appears that my original suspicion that the FOB was keeping systems awake because if it's placement close by. Well....the evidence doesn't support that.
My next "test" is I'm going to open the door, get in, start it, shut it down, and leave the FOB in the car.











