I was waiting in a parking lot to pick up my wife and left the car in Drive with Auto-Stop active for about 6-10 minutes. It drained the battery all the way down, and when I went to drive the car, it used 100% gas engine only and was extremely sluggish without the aid of the electric engine for a while until the batteries charged.
FYI to those of you who might think you are saving gas by leaving the car in gear and auto-stop while you wait, it WILL drain those IMA batteries quickly and cause gas waste.

 

Why would you let the car sit,doing nothing ,with the ICE running? Turn it off and conserve, I believe that is why you purchased a hybrid, is it not. Hal

 

His ICE wasn't running; the car was in auto-stop.

I find it strange that auto-stop drains the IMA battery so much after only 5-10 minutes, and have experienced this myself to some extent. If idling for a while I usually shift to neutral and turn the key to position II (accessory). Only downside to that is the radio/nav system having to reboot when you restart the car.

 

Normally the ICE will restart when SOC hits the four bars? My point is, why leave a car in this state? All kinds of things could happen! Hal

 

Was the Air Conditioning running? That'll do it.

 

Yeah, A/C was turned on. Maybe in Auto mode though. I don't remember.

 

So AC use (it runs off the IMA battery during Auto Stop) drained the battery, but:

This is not supposed to happen. If the IMA battery's state-of-charge drops low during AutoStop, the car should start back up, in order to prevent over-depletion of charge. I'd:

1. Shut down whenever you stop the car for protracted time, and/or shut of AC.

2. Run it by the dealership. Be careful though, it might be an out-of-warranty issue.

 

This happened to me as well, about 3 months ago. I was sitting for 10 minutes or so in auto-stop. AC was off. After about 10 minutes, battery dropped from 5 bars directly to 0 and went into forced regen. It was odd...

 

My hunch: it's not drain, just recalibration.