Proactively replacing 12v

Our 12v is original to our 2010 Prius and yesterday it tested at 12.81 v!

I routinely get north of 12.6 v, and I think the signs of degradation begin at 12.4 v. That's what the wife's 4Runner manual says anyway.

 

Are you keeping yours hooked up to a charger ray? Someone mentioned that the other day IIRC.

That's my ploy. Our car is typical used only every 3rd day or so. I have permanent connector for a CTEK smart charger installed, hook up is very quick and easy.

The charger runs through a cycle, then just ticks over, giving it little periodic boosts. Can be left on indefinitely.

 

Our Prius gets a minimum of 350 miles a week and sometimes as high as 500 miles. I do a once per month hookup to the Battery Minder 1510.

Seems to help.

 

I recently tested an Optima battery with the dealership battery tester. It wasn't the Prius one (skinny terminals) but it was the same size and capacity otherwise I believe. It ended up being good and ended at 12.88 volts.



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While that is a fair question.......as was mentioned before a couple of different ways.......you can NOT use ONLY the "resting" voltage as an accurate indicator of battery health, even if there is a sudden change. More testing needs to be done; and/or other factors need to be considered.

In general, a fully charged AGM should be about 12.8. If that is in fact your measured "standard" after sitting overnight with no charging and no significant load......then you might want to be a little suspicious when it creeps down around 12.5.

But note that I am NOT saying that it automatically means the battery is shot when your morning voltage check yields something 3 tenths or more below the "normal".

 

OK so here IS the problem with discussions like this:
Your figures are pretty much meaningless UNLESS you specify how long ago the battery was charged/charging.
For instance: If it was being charged (as in the car was running) a few minutes ago, your 12.81 might not be good at all.
If it has sat unused for a week, then it probably is VERY good.

 

i measured 12.56 the other day, but it can fluctuate. i test it in the morning, leaving the hood open the night before so i don't open the drivers door.
i don't have a specific number in mind, but somewhere below 12.4 is what i have focused on, based on numbers people have reported here, when the start having problems.
my car is garaged and coddled, but i do leave it every winter for 5-6 weeks.

 

From page 223 of the 1998 Toyota 4Runner owners manual:


I pop the hood Friday evening then test Saturday morning. So at least 10 hours to get the at rest voltage. A routine I have done for a fair bit of time.

Hope that helps

 

For popping the hood I always go in through the passenger door; avoids the brake pressurizing routine. Leave the car unlocked too.

I'd agree with Sam, that voltage alone doesn't tell the whole story: too many variables, mainly when you test, say fresh after charging, a day later, a week later. For the DIY'r the Solar BA5 is a step up in that regard. It works similarly to the one giving the print out in post #64, albeit simpler/cheaper, and no printout. Hey: take a pic of the result with your cell phone if you want.

That's likely based on a conventional battery. The AGM you can expect to be a bit higher.

 

unlikely.

 

Agree with others that the resting voltage has limited usage. However, since the Plug-in Prius 12v battery never is used for high load (such as turning over the engine) and the main 4.4kWh battery helps keep it topped up, the resting voltage could have some value as noted previously in certain situations.

I have recently checked the resting voltage on mine about a day after if was last used and after the 4.4kWh battery charged and it reads about 12.3v at the battery terminals.

At this point, I plan to periodically check the battery if the car is sitting unused for 2-3+ days to see if there is a significant drop-off. In that case I would replace the battery. Otherwise, I'm thinking of replacing the battery before next winter or if it will need to sit idle for 1+ weeks.

 

also, the pip (and prime?) charges the battery every time you plug in, something that validates mendel's trickle theory, although, both my 2004 and 2008 lasted 8 years without doing anything.

 

I replace the OEM Yuasa on ours somewhat prematurely I'll acknowledge, and @JC91006 suggested I hang onto it, as a spare. Just now I thought I'd check it and hook it up to charger, something I do periodically. It's not having any phantom loads, sits in the garage, but was slipping a bit. Also, doing the load test seemed to impact voltage a bit more. Some pics:


(at the outset)
(You need to set battery type.)



(Educated guess regarding CCA: the Yuasa doesn't say. I've read up a bit.)


(Ok here I screwed up taking the pic: the display toggles between CCA value and the letters "CCA", I managed to miss it. It was reading 310 for CCA, slightly low. Note also, it's giving a verdict: "OK" but needs charging.)


(And back to voltage, slightly dropped)

 

You could also purchase a jump pack for a fraction of a new battery cost and carry it with you. This way you are covered if your battery fails or if you need to help another motorist out.

I carry one for those reasons and if our battery fails, I'll purchase at that time but not inconvenience us in the moment.

 

I replaced the OEM in my 2012 PiP with a used Optima purchased 1/17. I transferred the old one into the 05 since it had a non-Prius Optima and I wanted to use that in a different car. Just had to swap the terminals back again.


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Is there a way to tell whether our '12 PIP Adv. (39,000 miles) is still on the original 12v battery? We bought it three months ago and it has been working perfectly. We'll be leaving next week on our PA-AK-PA road trip and thought it may be helpful to know. We've been driving/charging it daily and will be doing a lot of driving and less charging on this trip. I'm thinking it will be okay, but thought it could be helpful to know.

 

If it's black with a yellow label on top, it's probably original. The dealer replacements also say Toyota on them and the original does not. If you post a pic we can be see but, it is likely original and also should not give you any trouble. I passed down my original to my 2005 and it was almost 5 years old.


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Thanks. It looks like an original, right? Two more questions— What is the dark red cable end coming in the left side of the pic? I'm guessing it is to subwoofer or some such stereo mod of the previous owner. And, are there pieces missing from the upper tray? It looks like that tray is molded for specific items.

 

Yes that is an original battery. Yes the red wire is a stereo amp power wire. And yes I believe you are missing the cover to the triangle shaped tray. It should be carpet on top with a little strap to pull and remove. I believe the tow hook goes on the left (drivers) side next to the tire sealant and air compressor. But I don't think anything is missing from the tray itself. Bonus fact: the trays are shaped so you can store the window shade cargo cover under the cargo floor.


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Thanks. Yes, I have the carpeted tray cover. I had it off for the pic. I was just wondering if something specific was missing from the tray slots. You are right, the two hook fits in the other side.