Prius 2011 wont start

Dead 12v battery

 

Yeah I think AAA let you down, somewhere. My guess would be the battery is good but the connections not. Or it could be a dud battery.

Dutch Uncle advice: rather than polling the internet, get yourself a half-decent multimeter, check voltage at the battery, and at the under-the-hood jump start point, and post the readings.

 

Yes, notwithstanding what anybody said about the 12 volt battery, all these symptoms you're describing show that the volts aren't getting where they're wanted when they're wanted. That could be the battery or something else, but it's real.

An inexpensive multimeter, as Mendel suggested, between the jump point in the front fuse box and some body ground, is a good start. Then turn those weak headlights on and see how far that reading drops.

Then you can take the same meter around to the back of the car. Measure directly between the two lead posts of the battery. If that reading drops by a comparable amount when the headlights are turned on, it's the battery.

If it doesn't, put one meter probe on the battery's − post and the other on some exposed metal body ground. Does that voltage reading rise when the headlights are turned on? If so, investigate the cable that connects the − post to the body. Remove/clean/tighten as needed. (By "rise" here, I mean become further from zero, ignoring the + or − sign, which only depends on which meter probe you happened to put where.)

If that's not the culprit, repeat the test with one probe on the battery's + post and the other on the metal clamp attached to it. Remove and clean/tighten as needed if that's where the 'rise' is seen.

 

Most likely something is discharging the battery while the car is off. The sad truth is the same problem that took down your first battery could be discharging the second. Common parasitic loads are the rear hatch light staying on or something aftermarket that is drawing excessive current all the time. Anything plugged into the obd2 is suspect as well.

Often a battery charge will temporarily solve the issue and sometimes a jump carefully done with a standalone lithium jump box can get you going. If this is the case, have a mechanic run a parasitic load test. It should be less than 30 ma after two minutes.

See this post for more on parasitic draw testing:
Recent replaced 12v battery dead again, root cause? | PriusChat

 

I would try AAA again, there should be a warranty

 

Egg-z᠎ackly.

 

A battery can discharge in a matter of hours, even if it is new. If AAA can jump it again and it runs, the next issue is why did it discharge.

 

Jumping on this thread, because this just happened to me. When I opened my car door after work, the unlock chime wasn't typical, and the lights were on for a moment then off. The car was also making a groaning sound. The key fob blinked red/battery fine. Long story short, a couple of coworkers helped jump the car, and it started immediately - and showed a full battery. Of note, my car lights were in the OFF position. Had an uneventful 30 minute drive home. When I parked and turned it OFF, I opened the driver's door and the car chimed as if the car was powered ON. The power button was green (then orange/accessory). It started groaning again. I was unable to fully depress the brake pedal or restart the car. Powered OFF (well, I hope it's off), grabbed a snack and jumped on Prius chat.

This could be completely unrelated, but the driver side headlight burned out yesterday. Or did it burn out...

Ideas?

 

Most likely your 12v battery is toast. The "full battery" was your high voltage battery, not your 12v. Once running after a jump the car supplies its own 12v power for computers and other 12v loads. Best thing would be to remove the 12v battery and take it to a auto supply for testing. A new one will be about $200.

 

YES! 12v did the trick. Have a great week, all.

 

Consider the source, aaa.... "eco" mode will NOT drain the battery.
Unless you have a problem, then probably any mode could possibly do that.
But when the car is OFF, there should only be a slight drain on the 12v battery, this is normal.
30 minutes is not enough to charge the battery.
If you park your car outside, you could get a solar charge and keep it hooked up to the battery and
let the sun charge the battery during the day.
If it's garage kept, you can get a battery maintainer and keep it hooked up until you drive the car.
No more than 4.5 amps.

 

Maybe sis, maybe no.

I would look into compatible smart chargers, and maybe an electronic load tester. Couple of compatible options, respectively: CTEK 4.3 and Solar BA9.

 

It will discharge eventually, over time. And if you don't drive the car, it will discharge.
A decent vom (volt/ohm/meter) is good to have, to check the voltage.
Same with a battery charger, wether it's smart or dumb!