Anyone else having 12V battery issues?

You have a drain on the battery. When plugged in, the 12V is always in a charge mode along with the main battery. If you are not using the car, keep it plugged in. Locate the drain, interior, door, trunk...whatever. IMHO the batteries are much better off in a charged state, than to be dead and unusable.

 

Read the manual. It says don't let the car sit with the traction battery fully charged. I make sure my traction battery is discharged (less than 30% State of Charge) at the end of every day. When you charge the traction battery, the car also charges the 12 v battery. From Manual P. 93 "Leave a low level of charge in the hybrid battery (traction battery) when leaving the vehicle undriven for a long period of time." "Long period of time" is unspecified.

 

Also stated on P. 93 of the Manual:

After confirming that EV mode has switched to HV mode, turn the “POWER” switch off.

So, the above implies that you should switch your car from EV to HV mode before turning the Power Switch OFF, if you are going to let your car sit without driving it.

Use the charging timer function as much as possible in order to fully charge the hybrid battery (traction battery) immediately before starting off.

 

I use the same procedure as jbrad4 basically, but with the OP what does he mean by, after it sits about a week? Is he not charging the car? What's happening LURKAZUSA?

 

i went to cali for a week in may. left car at about 5 miles of ev range. unplugged, it was fine when i got back. this winter, i hope to go to florida for a month. hopefully, that's not a problem. it never was in my 04 or 08.

 

plug-ins should have a "vacation mode" for extended sleeps. vacation mode should keep the 12V battery topped off, keep the vehicle from freezing or boiling, send you a short daily health report, etc ... and tell you that it misses you and is waiting for you to come back.

 

perhaps some means of two way communication.

 

You might want to try a 12V solar charger clipped to the 12V battery and mounted in the back window. Get one with an overvoltage protector so it doesn't over charge. It won't help if you park in a dark garage though.

 

i don't think anyone is suggesting that it shouldn't stay reasonably charged for a lot longer than a week. you may want to have the dealer check the drain on the battery and see if it is above specs. or perhaps they didn't replace the original which may have been defective and only charged it up.

 

There is a charge point for the 12v under the hood in the same place as previous generations, you can trickle charge or jumper from there. In your case a quick 12v battery disconnect would work. Available at hardware store. Why the car would not start when both the traction and the Aux were both charged is beyond me. One question: How do you know the 12V was fully charged ? How did you check the 12V on your 2005? I also had a 2005 and installed a Bat disconnect switch. But, have found that unnecessary on the PIP as the 12V is always charged simultaneously .

 

There's something wrong with it. Take it back to the dealer ... then when they tell you crap, get in touch with Toyota's district manager.

There's no way a new car's battery should go dead in a week. And then suggesting you disconnect the battery? I'd be hopping mad and doing some bitchin' big time. Just say the words "Lemon law"...watch them jump.

 

Sorry, stupid computer. My post is below Chris's. Sorry Chris.

 

No problem Andy.

But I personally wouldn't mess with it. At all. It's up to Toyota and even though I think they're the best car mfg in the world bad things still happen with man made objects.

Take it back Lurk and do some demanding...to hell with diplomacy. You paid lotsa money to NOT have problems ... isn't that one of the reasons we buy a new car.

 

cough cough

 

Actually, there is. It's done through head unit menu. See the Owner's Manual pg. 640, then the appropriate head unit manual for your vehicle for instructions.

Maybe your 12V battery is too weak b/c it was drained too low at some point (could have happened in transit from Japan or something). I think the 12V battery status can be checked per this page:
Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 11