OLDchrisf

I bought a new interstate battery for my 2004 RX330. Got in my car about a week ago and it wad dead. Figured I left a house light on. Jumped it and went on my way. Two days later it was dead again. Brought it to local mechanic where I got the battery. Ran test. Battery and alternator show fine.

Something in the car is drawing more power than it should?

mowmow

Do you have an aftermarket alarm of sorts or other 3rd party toys that require constant power and drain the battery ?

txt

.
If you have a multimeter (MM) that can handle up to 10 Amps, you can measure the parasitic current draw.
The parasitic current draw should be less than 20 miliamps after the car is off for 30 minutes with all interior/exterior light bulbs turned off.
Anything higher than 20 miliamps means some device is drawing excessive current.
You can unplug the fuses, one by one, to narrow down the likely suspect.

My minnivan had a 400 miliamps parasitic current draw across a fuse that connected to all the doors.
I couldn't pinpoint the root cause to the specific part, so I brought van to the dealership.
The technician traced it to a bad door lock cylinder.