Which 12V OEM battery is better for Prius 2nd Gen?

All those batteries are garbage and they're charging twice as much as they should... But at least it won't die right away like a fake 12v made by Optima, whose criminal racket depends on fact that Prius 12volts don't start the engine, they just turn a computer on and HV battery starts the engine as well as charges 12v.

As in cold cranking amps of standard automotive battery is irrelevant and what you really need is max amp-hours. Here's the one I always buy for people: 12 Volt (12V) 55 Amp (55Ah) VRLA AGM Sealed Lead Acid Battery 55 AMPS HIGH CAP | eBay
It's only a $100 and only need a slightly longer mounting bolt and big flat washers to sandwich the terminals between.

 

Second-generation (2004–2009) Prius cars were originally equipped with one of two different sizes of auxiliary (12-volt) battery: a larger S46B24R size on cars with smart entry, presumably due to the higher parasitic load (dark current), and a smaller S34B20R size on others.

Toyota’s battery application chart (PDF) explains the difference between the two TrueStart parts: 00544-21171-325 is the S46B24R size, and 00544-21181-320 is the S34B20R size.

I’ve explained before how Toyota changes from original equipment to TrueStart batteries; this was announced in 2012 for the S46B24R size and in 2016 for the S34B20R size. I don’t know if the original batteries (28800-21171 for S46B24R; 28800-21181 for S34B20R) are still in stock anywhere, but I wouldn’t be surprised if an order for 28800-21181, for example, would be fulfilled with its 00544-21181-320 equivalent.

 

That's good to know! Thanks!

All I know is that both my Prius and Avalon have the OE (Panasonic) batteries in them. The Avalon has the original, but the Prius I'm not sure. When I got the Prius it hadn't been started in over 6 months (and hadn't been driven in about a year) so the possibly original 12V battery was dead. But after leaving it on a charger all night it now works fine. This and the fact my Avalon definitely has a 7 year old OE battery make me lean towards searching out those for replacement when I finally need one.

But now that I know about the 84-month prorated warranty with the TrueStart batteries I might go for one of those instead.

 

It is a bit disingenuous to describe the OEM 12V battery as garbage. It is also debatable whether it costs twice as much as it should. But you are certainly entitled to your opinion. It might help if you did not consistently pass off your opinion as fact.

I could not find a (genuine) 55 Ah/20-hour rate for only $140 (in our money), but my 55 Ah/20-hour rate was NZ$350 (~US$250) but still was cheaper than the quote from my local Toyota parts department for the OEM battery. I notice the price on my battery has gone down to NZ$295/~US$212 from when I purchased it back in 2014.

 

There's a pretty significant construction difference between a true "deep cycle" battery and a "starting" battery and they both have their own applications where they perform best. The Toyota batteries are more toward the deep cycle end of the spectrum.

I have a back up S46B24R battery and a backup S34B20R in the shop that I've purchased from salvaged cars. The S46 is rated for 325 cca, was manufactured 11/30/13 and still tests at 325-350 cca. The S34 is rated for 272 cca, was manufactured 12/23/15 and still tests at 300-325 cca. I also have a recently failed S46 manufactured on 7/7/12 that shows 12.4 volts, yet fails the first check done by the electronic load tester and registers only 150cca when tested. As with any battery, you never know for sure how long they're actually going to last.

 

that one you linked is all sold out…will this one work instead?

 

It'll be too tall, but you may be able to simply replace the bolt which holds it down with a longer one.

What price are you looking at, out the door?

 

Look here for loads of additional information and pictures!
Replace OEM 12V battery with Group 25 AGM | PriusChat

 

I went with this one -

- based on a post that I found on here a while back; has been working fine for past 3 years.

 

Ive been looking for hours to find a good battery thats not literally $300, this looks perfect! Can you send a link or a picture of the hardware I need to hook it up please?

 

Replace OEM 12V battery with Group 25 AGM | PriusChat

 

the terminals on this one are posts, the one in the ebay link has screw holes

edit: should I use something like these and then buy the adapters for SAE?
https://www.autozone.com/batteries-starting-and-charging/battery-terminal-charging-posts/p/duralast-side-battery-terminal-charging-posts-dl06072/95970_0_0?spps.s=5363&cmpid=LIA:US:EN:AD:NL:1000000:BAC:8366688869&gclid=CjwKCAiAwc-dBhA7EiwAxPRylOBuwYFv9G3cFZDStLmajBcGhtBx6oWaIvRqVL8LiR8geiwWvxQccxoCxGwQAvD_BwE&gclsrc=aw.ds

 

It's the same bolts battery comes with, just slightly longer... And you use washers slightly larger than connecting terminals in the car and sandwich them together. This battery is also a tiny bit taller, so the cross bar that holds 12v in place can be re-bent in a vice to manage that, or just use a longer mounting bolt, or remove the tray that battery sits on. Anyone of those three options will address that.

 

I have my battery and Im still confused how to exactly install it even with the larger bolts, do I need any more hardware/adapters to connect this to my car? Do you have a photo of one installed?

 

I "think" he's talking about putting a machine screw straight down though the center of the cable clamp (with washers on top and bottom) into the threads on the battery.

The original design has the clamp squeeze the around outside of the battery post.

This would squish vertically, kinda like a sandwich. It would "work" for the small amperage flow in a Prius, but I would just get an OE type replacement from Napa or Deka.

Posted via the PriusChat mobile app.

 

I looked around and found these - don't know if they will work.

Posted via the PriusChat mobile app.

 

thanks I've seen a lot of these, but isnt the "standard" size of these different from the prius posts? like i would have to get a new clamp connetors as well

Edit: I just noticed the ones you posted mention "JIS post", I havent been able to find any that specifically mention that size thank you!

Edit 2: They're sold out, lol. I suppose I'll try the sandwiching the screws for now and order SAE screw ins + SAE to JIC adapters

 

Toyota’s hold down bracket style is completely intolerant of any amount of height variation. Even 1/16” you’ll be stacking washers or shimming under/over the battery.

 

That's JIS. Here's ASE: