Hey everyone, I have a 2000 RX 300. It’s been a really good car over the years. Within the last year, I’ve been having dead battery issues. I have put two different alternators in it and put a new battery in recently. If it sits for more than 3 days, the battery dies. Sounds like there’s a parasite drain somewhere. Has anybody else had this issue and how did you resolve it? Thanks.

 

If your car completely stock? I'll take a guess and say you've been buying alternators at the local auto parts store if so that's likely your problem.

 

Are you saying the aftermarket alternator could be causing the drain?

 

No I'm saying the battery may not be getting a proper charge so it keeps going dead. You can test power draw when the car is off fairly easily if you have a test meter.

 

Before you embark on next part replacement, please determine what is wrong.
a) Battery
b) Charging system
c) Infrequent and short engine run time with multiple starts.
d) Accessory-load left on
e) Parasitic draw ... but then what is causing the draw. [Please do a search on parasitic draw and you will find a lot of discussion. Again, don't pick and run with the first hit as your problem may be due to some other item. Trust and follow, evidence based diagnosis.]

Replacing any time by hunch may cause further problems specially if the replacement was made with sub-par item. That will lead you into a position worst than where you started from.

Salim
PS: little things like auto headlight may overburden a weak system.