I have a 2001 LS430 with 81,000 miles The battery is 3 years old. If I don't drive it for 5-6 days, the battery will be discharged. I had the battery checked out today and the load was good. The charging system was also good. They said it must be an electrical drain. What is the most common cause of an electrical drain?

JN

 

Non OEM electronic add ons, lojack, remote starter, amp/audio, butchered up wiring from previous device, etc. can be common cause of parasitic draw. If it is a used car sometimes the current owner doesn't even know the device is there. What changed in last 6 months on your car? If nothing changed and the car wasn't discharging the battery when it was new, I'd replace the battery since it is 3 years old.

 

You can test for a drain with a test light. Just disconnect the negative wire from the battery, then connect the clamp of your test light to the negative wire, and finally, touch the end of the test light to the negative terminal of the battery. The light on the test light should not light up, or if it does, it should dim and turn off within 1 to 2 seconds. If the light stays on, even if it's extremely dim, then you have a short somewhere.

 

What kind of test light should I buy?

JN

 

Any 12V test light should work. Just make sure you don't buy a LED type, as LED types will not work for testing drains.

 

I did connect a non LED 12V test light to the Neg cable and Neg post on the battery . The light did light up. I was told at lexus that the LS430 had 20 computers that would drain current. Could this be my problem? I have 2 more days to see if the disconnected battery can start my car when it is connected.

JN

 

Might not be applicable to you, but I had battery issues a few months back. My connectors had a ton of build up.. Used a Baking Soda/Water/ Metal brush bath to clean it up and haven't had issues since.

On a second thought, any chance the rear seat heaters were left on?

 

I leave my UL with smart key for one - three weeks often at long term covered parking and never have any issues with the battery.

 

I had this happen recently. Dealership said battery was fine but it kept draining. I followed my gut and replaced it anyway and haven't had an issue since.

 

Sears told me to disconnect the battery for 5 days and connect it and try to crank the car. The car started with out problems. I did an amp test on the battery. I used an amp meter to connect one probe to the disconnected neg. cable and the other probe to the neg. terminal on the battery. After about one min., the amp meter read 450ma -500ma. Does any one know what the current drain should be on a 2001 LS430 ? Is this too much?

JN

 

This is a good basic procedure to follow:

 

I left my Amp meter connected to the neg. pole of the battery and the neg. cable for 30 min. The reading decreased from 450-500mA to 30mA. The past video was excellent.

JN

 

RA40, great video that answered lots of questions!

 

I left the battery in the car for 5 days and did not use it. After 5 days, The car started with out any trouble. The battery is good. I guess that a light was left on and that drained the battery. Thanks for all of the expert advice. As Paul Harvey used to say "Now you know the rest of the story" about batteries.

JN