This morning, I found my TCH unresponsive after being parked for about a week. I had left my Garmin Nuvi plugged into the cigarette lighter so that may have contributed to the problem. I hopped into my old car which I still haven't gotten around to selling yet and got groceries after stopping by Sears and buying a $30 battery charger/maintainer. It's not a rapid charger but a rapid charger or jump starting was exactly what I wanted to avoid.

A voltmeter indicated my battery was at 5V before I started charging. Three hours later, it was at 11V and I disconnected the charger and was able to start the car.

I don't get it... My 12v outlets are all switched power. Yours stay on?

Also the correct state of charge for that battery is 12.6-12.8 volts. You may want to put the charger back on it for a while.

It is good news though that such things are easy to recover from with this car.

I hope your first trip in that TCH after recharging that battery was to your dealer, since your electrical system must have a short circuit somewhere.

It could have been some light inside left on. I also found out that if you leave the car in gear and shut it off, the dashboard goes blank but the 12 V battery was still powering radio etc. I would assume after the car was started it was taken for longer ride to fully recharge 12V battery. I would keep checking that battery voltage and would ask dealer to run test for short, on the next oil change, but there are many ways to run battery flat so it doesn't have to be some fault with the car itself.

I had a similar problem. Battery was dead and was able to jump start it. I found that the kids had turned the reading lights on in the backseat. When the engine is off, these stay on and after a weekend of little use, they drained the battery. With all the computer technology, I would have thought they could have turned off ALL interior lights when the car is powered down.

IMHO there is no excuse for any car, especially a Toyota (which I have 3) to allow you to leave a light on for extended periods and drain the battery. The same issue exists on my Sienna. I have the habit now of double checking the dark garage at night to see if the kids left a reading light on. It is so simple for the microprocessor to figure out that the car is powered down for x period of time so it should shut the lights off. I wonder if this is something that can be reprogrammed by the dealer? I'll ask next time I'm there.

A little update...I have not had the problem repeat itself but I no longer leave the GPS plugged into the cigarette lighter.

Eric, I think you had a light on. Maybe a door was ajar, or something? Should be no power to the plug when the ignition is off. H

I left an XM plug and play unit plugged in all the time (until I got Toyota XM installed), and never had an issue. I left a Garmin unit plugged in all the time on my last Toyota, and never had a problem. Something else had to have been the cause.

"When you get to the fork in the road, take it." --Yogi Berra

I don't think any lights were on. All my interior lights are LEDs so it would take a bit longer for them to run down the battery.

I could conduct an experiment and measure the battery voltage daily with the GPS plugged in.