This comes from another forum source:
"Turn off the automatic light switch. The one that controls the headlights. Our
dealership told us that that has a constant draw on the battery. Since we turned it off, no issues"
I have an SC430 2006 - today with 22,000 miles on (I purchased new). Obviously I dont drive it very much. I've always had battery issues - even at the beginning, when I did drive it at least 3 times a week.
I have NOT yet tried the above suggested remedy.
But I will. Question is: "How to turn off the automatic light switch that controls the headlights?"
Is that the same as the switch on the headlight stick? - I always turn that down to OFF when I am not driving - along with the the A/C to OFF as well.
Good luck all!