I'll admit I haven't read all the threads on the 12V battery, nor really understand much about what it does, but, in a regular car, you can tell when your battery is going as the starter is sluggish, etc. You usually can tell (depending on the weather) when you're within a week or two of when it will die.
In the hybrid, (again, I'm not sure what the 12V battery does) are there any tell tale signs that the battery is dying? Does it have the same expected life as a regular car's battery (or is it longer as it doesn't need to turn over the engine to start)?
Thanks!

 

it is nothing more - nor less - than power storage for all the electronics. look at it as back up power supply. has NOTHING to do with starting engine.

yes, esp if you have nav system. if you do, you can log into data display. there are several data displays, one of them will show you battery voltage. if it's below 12V, charge it. it should be in the area of 13+ - 14V after charge and stay there for extended time. if it quickly drops down - well, you got it.

I had mine charged last year, it showed 14.3V as a result.

If you do not have nav system, tough. you can take it to say Autozone, and they will tell you this or that about its state, but keep in mind - as I am in real good standing with my local O'Reilly guys here - they plain told me, their testers are not made for deep cycle batteries. There's a very complex procedure, wit plotting results, to determine health of a deep cycle.

I'd say, to keep it on the safe side - replace it after 7 years. mine will be there next year.

 

Thanks, so without the NAV system, there's no way to know, is there? Will car still start if 12V is dead? I'm a bit confused, what happens if the 12V is dead? (sorry for being dense)

 

Most likely if the 12V is dead your vehicle will not start. Remember it powers the electronics required to start the vehicle, although it does not directly supply power to the motors it is still required in the start process.

 

Thanks...thus my original question.
With an ICE car, if you start it with a dying battery, you'll hear it sluggishly struggle to turn the engine over.
With hybrids...what happens, you show up one morning and the car is totally dead? My point is...are there any leading indicators or is it just "sorry Charlie"?

 

nope. it does not have starter. it starts off hybrid battery. electronics do not permit that battery to fall below a specific charge level, they will turn ICE on and recharge it.
if you car is d-e-d - dead - you have to tow it to dealership for them to charge hybrid battery and then you can go back to using it.
you can only approximate 12V battery condition. like I said - and I spent quite some time researching same question - you have to have special equipment to properly load test deep cycle battery.
like I said - sorry for broken record - for the heck of it, replace it at about 7 years. I came across post somewhere at Toyotanation, from end user, who had his 12V die on him twice - and he simply recharged it and drove the car. so, it's not a catastrophic failure. catastrophic is when hybrid battery goes boink.

 

Urkoz:
Dealer said this can't be done with my 2009 tcg navigation screen. How do you get the data screen?

Thanks,

PB!

 

Inquiry was to Urokoz's post about reading the voltage on the 12 volt battery on the navigation screen. Into the learning curve on this site.

PB1

 

I DO NOT BELIEVE that you can get into diagnostic mode on 07 models, and can NOT on 09 or later.

I can speak only for ones with nav unit - and just did it again. mof, I have entire write up posted back here (why there's no sticky-s here anyway?) on how to

press power button once>press and hold info button>start flipping light switch all the way forward-back> in 4-5 flips, diagnostic screen comes up on nav unit.

there's also way to test sound system and buttons on steering wheel. something about pressing 3-6-9 or some like that on nav keypad.

 

I have had two 12 volt batteries die in three years. Lucky they were both under warranty. Vehicle will not start when the 12 v battery is dead. You will need to jump start it. Measuring the voltage, the 12 v battery will show less than 12 v. I can't remember the minimum voltage before it will not start. After jump starting, if the vehicle is run, then it will charge up. However, if the battery discharges faster than before when vehicle is not used, ie overnight, then it is a sign that the battery is on its way out. The dealer can check to see if the battery can hold a charge.

My vehicle was purchased new, but about 9 months after the manufacturing date. The first battery probably sat for a long time and went through several discharge cycles. It only lasted about 2 months after purchase. Can't really blame anyone for that one. Dealer said that the 12 v battery is used to power the computer, thus has about 1/2 amperage as a regular battery (somewhere around 300 amps maybe). If you drive frequently, then it is not a problem. If you drive infrequently, it might pay to hook up a battery tender (designed for AGM batteries) to keep it charged.

I don't think the battery wears out any faster than a regular battery. Just that if you let the car sit for long periods without use - several weeks or more, then the battery will discharge. It powers security and other electronics with low voltage while the vehicle sits, so there is a small drain even when the vehicle is shut off.