Total loss of power after 1 day?

This sounds familiar. My new car went dead in the water in less than 15 minutes on acc. It turned out to be a bad aux battery and it was replaced under warranty. I'd recommend having the dealer test it. I believed (along with most people apparently) that if the car was plugged in, the battery won't go dead. Not true.

There are other possibilities of course. You may have a drain on the 12V system. A good mechanic should be able to trace the leak for you.

 

I suspect being plugged in will only charge the traction battery, not the 12V battery. If some 12V electrical load was left on (interior lights are a good suspect) The 12V battery will be totally drained in about 24 hours. Recharge that battery ASAP, as sulfation damage will destroy the battery fairly quickly.

 

It's been a controversy on here whether Toyota should have engineered a way to protect the 12V auxiliary battery from going dead, especially when there is abundant power available from the traction battery. Some claim such a system would endanger the traction battery, and others maintain it could be designed to protect both from over-discharge. For myself, it's less of a risk, knowing that the acc mode will time-out long before the aux battery will go dead, if it's in reasonably good condition. I'm not sure about interior lights, but I'd be surprised if they didn't time-out as well.

 

Recharge the 12v aux battery, start-up the car after a few minutes. Then you will have to trickle charge the same aux battery for a couple of days until it stabilize itself.
The surface charge to start up the vehicle will not be sufficient to render it fully usable in a long term; better yet, have it replaced under the vehicle warranty.

 

dealer proxy deep sixed it before selling it to you. they tend to do that when on the lot or in the showroom. it's a small fragile battery compared to what they are used to.

 

Toyota may be squandering their stellar reputation just a little. A dead 12V battery is easy to blame on the customer, justifying a visit to the service department, and the subsequent opportunity for up-selling other repairs.

 

nah, this has been going on for years.

 

Can leaving the charger door opened but not plugged in cause significant drain on the 12V battery? I accidentally forgot to close it one night, and have been double checking ever since. I assume it's a small LED so it shouldn't be too much of an issue.

 

It's a safeguard that works with a reasonably good battery, but it fails if there are repeated draw cycles without recharging. Such was the case in the showroom of the dealership where I bought my Prius Plug-in. Apparently people were opening doors and leaving lights on all through the day, for day after day for 2 years. The battery was destroyed when I got it.

 

It's possible, if it never shuts off. The aux battery isn't very large, and if it's in poor condition, it may not take much to drain it.

 

It doesn't turn off on it's own. I thought that was pretty stupid on behalf of Toyota's engineering.

 

Yes, stupid engineering, if your 12V battery has a slow drain on it indefinitely, when the door is open while the charger is plugged in.

 

Note that you don't need a lot of peak amps since the 12v battery isn't actually starting the engine. All the 12v battery is doing is booting up the hybrid system. Now if you own another vehicle that requires the amps, that's a different story.

 

That's on the plus side, but on the negative side, below a certain voltage, you can't turn the system on, rendering the car:
Dead in the water.

 

Others point out that a complete shutdown and disconnection of the high voltage system is necessary for the safety of crash responders. Most of them won't touch a hybrid or EV without very strong assurance that they won't be electrocuted.

 

I have one of those, but here's the one I carry in the car:
Stanley Tools Simple Start Battery Booster: Decor : Walmart.com

But it's no good without one of these:
http://keysandsigns.com/image/cache/data/caraccessories/poloi-500x500.JPG

When the battery is dead, so is the 12V socket, therefore you have to go straight to the boosting terminal on the fusebox.

 

Very serious overkill, that peak capacity is meant to help turn the starter motor of a traditional nonhybrid.

The Prius 12V battery should not be charged faster than about 4 amps, easily with the capacity of much smaller chargers. At actual startup, the power brake system may briefly pull 50-ish amps.