2005 Prius not charging 12v while driving. 195k miles

Chap is absolutely correct. Your 12V battery and the respective charging system are fine. Your problem is elsewhere and you need to address that.

 

There have been a couple of reports (rare it's true) of the main 12 volt battery cable corroding through inside the insulation. In both cases this was near the front of the car as the cable goes up to the fuse box. The cable in both instances was made of aluminium and a small perforation in the insulation allowed salt water in to the aluminium, and corroded the cable till there was little or no conductivity.
I appreciate this is a long shot but it is worth checking out. First by checking one end of the cable to see if it is aluminium then take it from there.

John

 

I never really doubted that, with enough ingenuity, we could stretch the thread out by even more posts about batteries, even if they have to be about "rare" and "long shot" hidden cable corrosion, before arriving at the really rare, super-long-shot, totally black-swan notions, like that the brake lights could actually be about the brakes.

-Chap

 

Yeah might be time to take her to the dealer as we might've just exhausted all common and un-common answers.

 

Or even ... just ... read ... the brake codes ... using a Mini VCI or an inch of jumper wire for the blink codes, i.e. a method known to work and pull Prius brake codes, since only an Ultragauge was mentioned earlier ... seeing that the brake warning lights have been on for twenty-four posts already and the common answer of reading the codes to see what they're on about won't have been exhausted until somebody, someday, tries it ....

-Chap

 

Not to take this thread, as interesting and riveting as it may be, in another direction, but I have to ask. Why do you have your complete home address listed in your profile? In the world we live in, I find this rather disturbing... If that is not your address, I find it even MORE disturbing. I can't seem to get past this! It is really bothering me! I can even click on it and see what may or may not be your home... I can't even remember what this post was about because I am so fixated on the fact that anyone would do this...

 

Idk why that is but every reading you give us says good battery. How about the next time you get those lights and it leaves you stranded, measure the battery voltage and post it here.

 

My guess is OP does not have an adequate device to read Prius codes. There is no way no codes are logged from a NO START event.......along with an eventual red triangle coming on.

Fiddling with the battery when it's not a battery problem will often erase all codes stored in the car that would point you to the actual problem.

 

I agree with usnavystgc, that would be a critical piece of information that's been missing from this entire thread. Coastiegunner, I see that you have mentioned (in post 1, post 26, and post 27) that your car at times will not go READY. In the same places, you mention that the times it won't go READY are immediately after it has posted several, potentially important, dash warning lights. Nobody is suggesting that's "a coincidence"; in fact, if you look in the manual you can find lists of which trouble codes are specified to prevent the car going READY. In all of your posts, you sort of turn it around as "but, why does it report these problems only just before it refuses to READY?" instead of the (rather less mystifying) "why does it only refuse to READY just after reporting these problems?" but maybe it's good to be able to say it both ways.

Also, in each place you say that, you clearly believe it's not going READY because the battery is too low, but you have not yet, anywhere in a 30-post thread, included even one observation that could help any of the rest of us follow why you think that. I'm not saying necessarily you haven't made such observations, only that if you have, you've never clued us in on them. Are you observing that every time the car won't READY, also the dome light is super dim, the doors only half unlock by remote, the brake accumulator sounds like a dying goose, and the car won't go READY? That would be valuable information to have. So far, all you're saying is "goes great, goes great, then there are these warnings, then won't go READY" and that, by itself, would better support a different interpretation than the one you're giving it. Especially when, so far, you have reported a lot of battery measurements, and you haven't reported any that would suggest a battery problem.

The best way to fill in that gap would be usnavystgc's way: seeing that you do have access to a multimeter, you could easily just report the battery voltage the next time the car has refused to READY, and that's more concrete and quantifiable than any dying-goose business. That's an easy test you can do without going anywhere, spending any money, or needing anything you don't have.

The thing about scan tools (I can't speak directly to Ultragauge, I don't have one) is there are a bunch of different computers in a Prius and scan tools won't all talk to all of them, meaning the fact that your tool has shown you codes from one or some of the computers in the past doesn't always mean you can say there are "no codes" on another occasion, if the ones you need to read are in one of the other computers. Anyway, there's also an easy test about that: make a deliberate problem in your brake system (pull a HYDRO MTR relay, say), wait for the dash light, then see whether your Ultragauge reports the correct code for that problem. Again, something you can do without going anywhere, spending money, needing anything new.

For that matter, just jotting down the blink codes the next time you've got those warnings on is another thing you can easily do, in a couple minutes, wherever you are when it happens, with no money, no hassle, and an inch or so of wire or a paper clip.

-Chap

 

Now that you have removed your complete address from your public profile, I have deleted the image of your house. I know it was harsh, but I hope you learn from your mistakes...

 

Doesn't that entire side-issue seem like something that could have been handled effectively and discreetly by PM?

-Chap

 

In retrospect, you are probably correct. I was so shocked by it, it didn't even cross my mind. I am so tired of the erosion of our privacy in this country that I am loathe to see it given away, freely... Like our politicians forgetting the fifth and tenth amendments, and the overreach of our judicial and executive branch of government. But, I will leave that conversation for another day.

 

Oh i thought the whole point of social media era was to take 300 selfies of yourself everyday, post them to your real names on various social media outlets so everyone can see.

 

OP---what happens after it strands you? do you jump it and its ok? do you have to charge the battery?

 

Abs lights then red triangle turning on sounds more like inverter overheating do to failed electric cooling pump or hv battery overheating..
from cloged cooling fan.

Coastie all your 12 battery readings seem good and battery drain when prius is off is exceptional at .0014
my 12v battery drain with scanguage connected is around .035 amp.

It's very easy to check if 12v battery is charging.. turn on headlights. Then ready prius. one second after depression of power button you will see headlights become 15% brighter This is 13.8 volts being supplied to 12.6 volt battery (charging).

your prius could not run a week on 12v battery that has no charging (only 2.5 hours without lights).. Check inverter coolant reservoir for turbulance indicating coolant flow.
Inverter coolant pump can also be heard at driverside front fender (with hood open) . also hose from coolant reservoir can be felt for vibration from coolant pump motor/coolant run/flow.

When inverter over heats or when traction battery over heats. regenerative braking is disabled lighting abs warning lights..

Your prius only needs to cool down to restart. no jump start nessary.

Am I right?

 

I know this thread is super old but did you ever figure out what was wrong with it?

 

I went back a few posts and, as usual, the discussion ran off the rails and went elsewhere.

The most likely cause when it APPEARS that the 12 V battery is not charging is: The battery itself is worn out and either won't take a charge or won't hold it long.
It is easy to check the charging voltage with a voltmeter.

 

Thanks! We replaced the 12v today at the Toyota dealer. Hopefully, that fixes the problem. When we realized that we have had the same 12v for the entire 13 years we've owned the car, we figured it might be that!