Need some help replacing the 12v battery, any info would be appreciated!

The 12v battery doesn't start the car like a normal battery - it provides power to the computer and all the various solenoids, switches, etc which "starts" the car.

The car actually starts moving only by electric power (hybrid battery), at least for the first few nano-seconds, and in reverse, always. When the car decides it needs the Internal Combustion Engine running (ICE), it's the hybrid battery which provides the power for that. That said, the ICE will sometimes run when you first "POWER" up, if the Climate Control is wanting heat, or the Hybrid battery is low.

But if it's "flat" at the start of the day, but works OK during the day, that could well indicate that it's not healthy enough to survive through the night. [The same will often happen with a "normal" car which will be flat when stone cold, but be able to start fine when the battery is warm and has received some recent charge.]

Have you tried putting a battery charger on it overnight?

I've read most posts with Gen 4 - there haven't been many 12 v batteries, maybe 2 or 4, and I haven't seen any diagrams or videos, sorry. Though $300 sounds reasonable - I heard someone having to pay $500 for an "ordinary" car here recently.

You could check with the dealership who could check that there are no other reasons why it went flat.

Is it new to you? - if not, could it have been sitting in a dealership for a while?

 

If the battery was low on charge when it was tested it will test bad.

It needs to be on a charger and fully charged before testing or it will fail.

I don't know if the local parts stores carry a replacement battery so give a few of them a call, most will change it for you I believe. If they do just watch them.

This one should fit.

http://www.batteriesplus.com/battery/car-and-truck/toyota/prius/2016/l4-1.8l-325cca-hybrid/sli51pagm

Sam's Club handles Duracell car batteries.

This may fit, it's cheap.
http://www.oreillyauto.com/detail/b/premium-5598/battery-accessories-16452/battery---automotive-16864/battery---best-fit-16245/ec27e4e51018/super-start-premium-group-size-140r-top-post-battery/140rprm/5769218

 

I think AutoZone doesn’t know they carry it. I haven’t seen one firsthand, but from all the information I can find, their Duralast H4-DL battery should be a direct replacement, as I’ve mentioned previously. AutoZone’s database only shows that it works in a Chevrolet Spark, and no one has bought one and reported their experience here, but the size, terminal arrangement, etc., appear to be a match for the original.

That one is an AGM battery—quite suitable for 2015 and earlier Prius cars, but not needed for a 2016—and it may be physically too long to fit in the space available. There are several websites that apparently haven’t been updated to reflect that 2016 and later models use a new size and type of battery.

The definitive instructions are in the Repair Manual (more info). You can find the text and illustrations in the Chilton Library database, to which your local public library offers access at no charge.

No, nothing is yanked loose—for each terminal (negative and positive), you just loosen one nut, then lift the assembly off of the terminal post. There is also a battery clamp with a hold-down bolt.

That’s a “core charge,” reflecting the recycling value of the old part, and any reputable seller of parts—dealer or otherwise—will refund it whenever you return the old part, even if it’s a few days or weeks later.

 

Here is another resource for battery information.

Group Size
140R
Minimum Cold Cranking Amps
480
http://www.autobatteries.com/en-us/car-battery-finder?year=2016&make=Toyota&model=Prius&engine=L4-1.8L&find=find

 

Is it possible your driving only includes short trips, thus not recharging the 12V completely? Do you ever run accessories while the car is not READY, the 12V battery only recharges when the car is in READY? The Prius 12V battery is not overly capable. All it is designed to do is power up some electronics and close some relays that brings the big Traction Battery online. It's hard to believe a 2-year old 12V battery is bad. I believe it is simply not getting a proper recharge.

 

welcome!
there is another thread here today with a gen4 battery source at a local auto parts dealer for $150. plus 25% off first time customer discount.

replacing under the hood is easy, just loosen the nut on the nehative post first and wiggle off, then do the positive. and there is probably a hold down bracket.
reverse order when replacing.
all the best!

 

I haven't had a reason to remove my battery yet but the terminals are different than any I have ever seen before but not rocket science either i'm sure.

 

Remove and replace isn't the problem. It's the complicated stuff you have to do once you reconnect the new battery.

SM-T820 ?

 

And the answer is?

 

Going from memory: open/close the lid over the gas cap before doing anything else, and drive in a straight line for more than 5 seconds at a speed higher than maybe 20 mph. I'm not peeking, how'd I do?

 

The Manual talks about it - there are 6 pages about it worth reading - also a link to what needs re initialising. My copy of the USA Manual is page 711 ->.

It suggests consulting the TOYOTA dealer - but then says to go to page 760 (my copy of the manual - yours might be different page).

 

1. PROCEDURES NECESSARY WHEN AUXILIARY BATTERY TERMINAL IS DISCONNECTED/RECONNECTED

1. 
   
   
   • After the power switch is turned off, the radio and display receiver assembly records various types of memory and settings. As a result, after turning the power switch off, make sure to wait at least 120 seconds before disconnecting the cable from the negative (-) auxiliary battery terminal.
   • After the power switch is turned off, the navigation receiver assembly records various types of memory and settings. As a result, after turning the power switch off, make sure to wait at least 120 seconds before disconnecting the cable from the negative (-) auxiliary battery terminal.
   • When the cable has been disconnected and reconnected to the negative (-) auxiliary battery terminal, open and close the fuel lid before turning the power switch on (IG).
     HINT:
     
     The accuracy of the fuel receive gauge changes depending on fuel tank deformation caused by internal pressure. Before turning the power switch on (IG), equalizing the fuel tank pressure with the ambient air pressure by opening and closing the fuel lid after disconnecting and reconnecting the cable to the negative (-) auxiliary battery terminal increases the accuracy of the fuel receiver gauge.
     
     
   • This is from my online manual for a 2016 Prius.

 

"The accuracy of the fuel receive gauge changes depending on fuel tank deformation caused by internal pressure. Before turning the power switch on (IG), equalizing the fuel tank pressure with the ambient air pressure by opening and closing the fuel lid after disconnecting and reconnecting the cable to the negative (-) auxiliary battery terminal increases the accuracy of the fuel receiver gauge."
I have never heard the fuel cap referred to as a lid.

 

Lid sounds more like the door on the body work.

 

The fuel lid is the door, not the screw-on cap for the filler pipe. They want you to press the button to open it, after reconnecting the auxiliary battery, since that also causes the engine control module to open the fuel vapor-containment valve, equalizing the pressure in the tank. See the discussion of the evaporative emission control system in New Car Features (more info).

 

This may only be relevant to USA models - the rest of the world, I believe, doesn't have this.

 

Being old school, I would have read that and thought they meant to take off and then put back on the gas cap. That's how we did it way back when. If it stated "opening and closing the fuel door" that would have made more sense. But now that I think about it, I would wonder how opening and closing the fuel door would do anything. Damn, cars are so complicated these days.

 

My Radar detector a couple times came up with battery low message and during the last service they gave my battery a yellow check in the service sheet. I checked the battery itself and its usually always right around 12.3 or so volts, but on a colder morning, Im sure it could be less. Never the less, I got out my Battery tester the other day and decided to test the prius battery and tested right around 200cca and this was roughly in 80 degree weather, ideally it supposed to provide 295cca. I've had good luck with the toyota oem batteries in the past but this one seems to be really poor with all the other battery threads already out there. I've even thrown it on the $100 battery charger I own that supposedly repairs batteries so I am thinking these batteries are crap that came in my car. Posting the pics to help anyone else out there. My current mileage is 51k, 2016 prius, picked up 2.5 months after car was built. I haven't yet got the official message yet on my multifunction screen saying low battery but figured I would post this to help any others out with some real info. By the way, I tested a couple other batteries I have and the tester tested them spot on with the sticker.