My Lexus GS300 is struggling to start and eventually dies. These past three months I have replaced the battery with a brand new one three times. I finally thought I found the source of the battery drain, my aftermarket amps; however, turns out it's not the problem. After fully disconnecting, and shutting off, the amps my car is still struggling to start. Each day, it takes the car longer to start. It's already been inspected, and tested, several times. The alternator is in great condition and the starter does not need to be replaced. So what is causing my car to struggle with starting and eventually draining the battery? It takes approximately two weeks for the battery to fully drain and the car can no longer start. Weirdly, after getting it to start the first time, and letting it sit for several minutes, it will start up instantaneously the second time. It's when I let it sit for several hours that the car struggles to start. I drive it around constantly but it still struggles to start and eventually dies after two weeks like clock work. Any ideas as to what can be the source of the problem? We have tested the car with a volt meter and discovered there is a short somewhere, but it's not any of the fuses. I'm getting desperate and cannot afford to take the car in for a full inspection just to have a shop claim a false problem, such as it's the perfectly good alternator, so they can charge me a ridiculous price. Please, I need advice!

 

You're going to have to do a parasitic load test across your fuses. Something has to be staying on. There are many tutorials on the Web, and YouTube on this.

 

Other than the amp, everything is stock on the car. Could a stock part be draining the battery?

 

Yes, it could be anything.

http://automedicsafrica.com/cause-of-car-battery-drain/

 

Thank you, I'll start researching how to search for the drain!