When to Replace 12V Battery

do you drive it infrequently?

 

@NutzAboutBolts video #23 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Shows how to uncover the positive terminal cover in the under-hood fuse box. This is what you want to use if you're wiring in a quick-connect of some sort.

 

2010 Prius with 175k miles and still going with the original 12 v battery. In NJ kept inside a garage.
Maybe it’s time to get a new one before I need to.

 

I just tested this morning in vehicle signal mode and got 11.9.
Then I turned the car on it steadily dropped to 11.3.
Yeah time to replace
I saw a deal at Napa online to pick up at store and with the 20% off coupon it will cost 167$US
Thanks peeps!

 

Yeah since you have framed it like that just replace before it goes bad after 4 - 6 years sounds the prudent thing to do.
After turning the engine on the reading went to 13.7 only btw

 

that's just reading the converter output

 

i bought a slow charger for a lawn mower because one summer the battery was dead. I charged it that summer and it has been good for a few years now and i didnt have to re-condition that battery again.

now the car's battery is completely dead. first read was 10v. i've used that charger to charge it for 23hr, and it is reading ~12.3v no load. I'v read a few tricks to test the battery in this thread that i will definitely try. but im wondering why is nobody talking about recharging their battery? or is it jjust too obviously a waste of effort that i should just buy a new batt?

and for anyone curious mine lasted 7 yr. so i cant fault it. also how come costco.ca doesnt list battery for prius?

 

Costco doesn't list a 12V Prius battery in the US either -- not even as a special-order item -- even though Interstate (the manufacturer of the batteries that Costco sells) lists a Prius 12v battery. BUT that Interstate battery is not much cheaper than the OEM one from the Toyota dealer and has a much shorter warranty.

 

Canadian Tire has a battery

 

When the battery went down to 10V or so, it’s probably dead. It can be recharged, but it won’t keep the charge long. So you may get a days/weeks, but that battery need replacement anyway.

 

You aren't looking close enough.

IF.....the battery is fairly new AND you know what caused it to be low, then a one time recharge will probably work.
And using a tender type charger is discussed ALL the time here.

OTOH, if your battery is 7 years old, it's not worth the effort except maybe to get enough charge in it to drive to the parts store for a new one.

 

In the USA, try Pep Boys. I got a good one there and paid $119 I think. IMO....once you reach a reasonable end-of-life on your 12v (4-7 years depending on use and climate) it's best to replace it. After it fails you even one time, it's not worth the risk of a future stranding.

 

To get back on the question, when to replace 12v battery. I'll replace it when it no longer starts the vehicle.

 

My 2011 wasn't starting on the first push but would eventually go into ready mode, this happened about 4 times. Then one colder morning I couldn't get it to go. I picked up an OEM from the dealership yesterday (about $240) I did the swap today and pulled out the original with a date code of 010711.

 

Pep Boys was selling a compatible Bosch battery IIRC, but somewhat recently there were postings here that that was no more. But who knows now; doesn't hurt to check.

 

The only (allegedly) Prius-compatible battery I see at my nearest PepBoys is an Optima yellow-top for... $333.99!!!!

 

Ouch. I got that battery 5 years back from SaskBattery, shipped free, for $219 CDN.

 

O"Reilly has the Optima for $250 or their own brand for $200. I have had the O'Reilly battery for 6 years and it is still going strong.

 

I just looked up my email invoice from PepBoys. I bought the Bosch Premium Performance Battery, Size 51. I actually bought it online and my local store had it in stock. But you should be able to have them ship one to your local store if they still carry it. I bought mine in June 2019.

BTW - I was wrong on the price. List was $194 and they usually have a 25% off battery coupon available online - I used a coupon bringing my total out the door price to $146. I installed it myself.

I was pissed off at the outrageous prices on Prius gen III 12v batteries so I toyed with the idea of installing a Walmart 12v with matching posts and skipping the vent. Glad I didn't do that. I probably would have gotten away with it, but that vented Bosch battery is a direct OEM replacement with the correct vent and fittings - it's nice if you can get it.

 

Advance Auto has Diehard battery for the prius now.