Anyone experienced this particular peculiarity? Monday morning it was -20F here and I started the car to let it warm up for 20 minutes. I have in the past in extreme cold let it "warm up" for up to an hour knowing the motor would shut off once it got warm. This time however I got in to drive and the turtle light (warning light) came on and I knew this was a warning to drive slowly because the main battery is discharged or overheated or something so I checked the energy monitor and the battery showed empty and no power flowing. as soon as I started driving the battery started charging and was soon up to full and the turtle light went out. The last time I know that the car ran normally was after Christmas it warmed up and shut off and no warning lights. I have an appointment with the Toyota dealer on Monday to check it out plus the 90k mile checkup. I hope this isn't a sign of major failure? This is 5 days later and I have been watching the energy monitor for a change but still not charging unless the car is moving.

 

"Monday morning it was -20F here and I started the car...and the turtle light (warning light) came on..."

This is normal in cases of extreme cold. The turtle light also indicates that the battery coolant system is operating inefficiently due to the cold. According to the manual you should avoid rapid acceleration while the light is on. The coldest morning last week my turtle light was on the whole way to work, about 15 minutes. My battery was not discharged, so it did not indicate charge while standing still.

The battery system in a 2002 Prius has its own coolant system, noticable by the black vent near the rear door on the driver's side. I have noticed that in extreme cold conditions it takes a lot longer for the battery to warm up so it can charge efficiently. Also, sometimes in cold weather, the engine will run at a stop light even if the battery has sufficient charge because the fuel emissions system is not warm enough to run efficiently. Everything returns to normal when above zero weather returns.

 

That's what the dealer said. I shouldn't worry about rabbits or turtles but watch for the exclamation point.