Parasitic Load


I own a 2004 Toyota Sienna XLE.

The battery died so inasmuch as the vehicle was three years old I justI replaced it without a second thought. Then after a few days the new battery died.

The alternator checked out to be good so I decided to find out if there was a parasitic load.

The ammeter read zero until I opened a door; with all the lights out and everything turned off.

Within 30 seconds of the door being opened the ammeter jumped to a 10 amp drain: Not 10 milliamps but 10 AMPS!.

The new battery probably died because I left a door ajar, so I have been diligent in making sure every door is closed tight at night and have not had any more dead batteries.

Does anyone know if that 10 amp drainage with an open door is normal and to be expected?

If not normal, what do I do about it?

I would appreciate any thoughts or suggestions.


How many lights come on when you open the door? You’d have to add up everything to see to total load.


Ten amps is about 120 Watts. That seems high for interior lights alone. I wonder what else may be going on. I would suspect it be be about a quarter of that.


You could probably figure about 25 watts for each courtesy light that is on inside the vehicle. It sounds like something came out of the sleep mode when the current jumped up so high. I would guess this is normal if things are working ok but I couldn’t tell you what is causing the draw. You didn’t state what the difference was in current from when the door was first opened and then later. I would guess the lights would draw at least 5 amps of the total current draw.


I had all lights turned off.


In my original post please note that all lights are off.
Everything is turned off.
I appreciate your interest.


Good point: When the door is closed the ammeter goes back to zero. When the door is reopened, within 30 seconds the ammeter jumps to 10 amps. Remember, everything is turned off. There are not lights on. The radio is off. Everything is turned off.
I do appreciate your interest and assistance in this matter.