Stupid newbie mistake--how screwed am I??

Are you freaking serious? You're crying over leaving the dome light on for 4.5 hours? I hope you're joking because this is gotta be the st......... never-mind. Dome lights draw about .5 to 5 watts per bulb. On a healthy battery, it would take at least a couple of days to drain the power. I recently replaced my dome lights in my Tacoma to couple of 15watt high power LED dome lights. I left the lights on for 2 days and my Tacoma started right up. The Tacoma needs 200+ amps to start the engine where as the Prius only needs about 20-30 amps to boot. Those people with dead prius batteries were letting their cars sit for weeks sometimes months in parking lots. It doesnt take that much to jump start a prius. You could do it with a drill gun battery.
A regular car battery can't be deep cycled. If they are cycled they can only be charged back to 70-80% of its original capacity. Since original capacity is 200-400% of what a starter needs to start a car, after it's been cycled and charged back up, the engine starts up like a brand new battery even though it lost 20-30% of its original capacity. My parent's 98 Sienna's original Toyota battery had been deep cycled at least 10 times in its life. It lasted 7 years before it couldn't recover enough to hold a charge.

If it makes you feel any better, read this... Prius Startup Current about Gen II 12V battery and some info on the HV battery. Gen III should work the same.

 

I would just add that you may not even have left the light on. If left in "Door" mode, the interior lights come on automatically when you approach the car while carrying an SKS key, in anticipation of you getting in. Neat, huh? But the first time I saw it, I thought I'd left the light on, too.

 

Since it started back up you probably dodged the worst of it. Battery capacity is most likely reduced but not critically...yet. Just keep an eye on it and try not to do it again.

Once the car is successfully started, all 12v power comes from the inverter...it's just the power-up sequence that depends on good current from the 12v battery. THAT can cause wackiness!

 

I killed the battery on my truck once, call the auto club for a boost been running for 3 years no problem
people have to chill out more

 

I'm in accord with WMCBRINE's opinion that you may not have left the interior lights on at all.

That being said, "IF" you clicked the map light switche(s) thinking that you HAD left them on (but really had not) then you may have turned them on when you thought you were turning them off.

You might check it this way:
a. Turn off your car
b. Lock your car.
c. Close the garage door (so it gets card inside of your garage) and go inside the house (this is important so you get far enough away from your car that the SKS doesn't "sense" that the key is near by and turn on the "welcome lights").
d. Wait long enough for the interior lights to auto dim --> and turn off (about 60 seconds).
e. Now, open the house door to the garage and look at the car. Are the interior lights on? No? you're OK. If "Yes", then appraoch the car, unlock it and turn off the map light (or whichever light is illuminated).....and repeat from step "a" until there are no lights on inside of the car when it is locked and the SKS is not near the car.
--> Alternately, you can leave the car unlocked, but leave the key INSIDE THE HOUSE (or just far enough away that the car doesn't sense the SKS) and then go out and see which lights are still illuminated. if there are none, you're good to go!

 

You should be fine. In the worst case scenario you shaved a few weeks off the life of the 12V battery. It's no big deal.

Tom

 

As long as you were able to start it, and drove it awhile to charge that bad boy back up, you are probably good.

 

1) You don't have to drive it to charge it. Just need to put in ready mode and let it sit. The HV will slowly charge the 12V without going anywhere. When the HV gets low, the ICE will start long enough to recharge the HV. Open the garage door so the engine gets air and you don't get CO.

2) Always lock the car with the door handle. It will fail and beep if you've left anything on.

 

My research tells me that there is no tangible reason to believe you have done any long term damage to anything but your own personal psyche...relax.

But when things like this happen, it could be a message from the universe. I'd trade your Prius in immediately before something else happens. You're obviously living in fear and that's not harmony between man and machine...

Really, think it through, while inconvient what was the worst that could happen? Worst case the 12V is drained to the point of unredemable failure (astronomically unlikely given circumstance) and you'd have to purchase a new battery or keep your mouth shut and pretend you have no idea why it failed and see if Toyota would cover it, in either case you'd emerge in good shape.

 

a decent lead acid battery should be able to withstand 10-50 significant discharges with only a minor change in its life. for what you did, you should still have had significantly more than 50% of your capacity left. its only when lead acid hits 65% or 35 % discharge that anything at all happens. (that figure has been debated)

now, with all that in mind. remember any battery has a finite life. proper charge management will help you get most of that life out, but no matter what you do, you have used up a part of your battery's total charge. but as others have stated, you did no real harm

 

Dude, decaf. This is the newbie forum. It's exactly meant for these kinds of questions. Hybrid vehicles with two different types of batteries can be unsettling for many people until they get used to what does what.