Replace 2005 12 Volt Battery

i paid $210. plus tax at the local dealer. i doubt the headlights are a symptom of a bad 12v though. maybe a loss of a few mpg's as the hybrid battery tries to keep it charged, and the engine runs more to charge the hybrid battery.

 

Not too long ago I bought one at the dealership and installed it myself. It wasn't difficult. The worst bit was loosening the nut at the negative post, as it faces "the wrong way" towards the back of the car, which makes it hard to reach. A tiny ratchet (about 4" long) worked but a normal size 1/4" ratchet (more than twice that size) was unusable in the same location.

Just be sure that you don't let the hatch close while the 12V is out of the car or disconnected or you will have to crawl into the back to use the manual hatch release. That is awkward and uncomfortable.

As you noted, MPG decrease is a symptom of a very weak 12V battery.

 

Oh dear... Prius brake maintenance has a few gotchas.

If just doing brake pads clean up and relube, you want to disconnect the 12 volt negative cable, and/or make REAL sure the driver's door is not opened.

If you're going to drain brake fluid, then you either want to have Techstream, OR put the car in "invalid mode".

More info on those if you're interested. Simplest route: take it to a dealership, tell them the full story.

 

Very best battery that will outperform all the others and only costs $100 is this one: https://ebay.us/vN4JsP

If you decide to buy this one let me know and I'll post pics of the bolts and washers you need to buy at hardware store so terminals mount properly...

 

shouldn't the mech fix the brake lite problem for no?

 

there are lots of hid threads

 

2nd-gen-toyota-prius-hid-to-led-conversion.190604
number-one-worst-thing-about-owning-second-generation-toyota-prius
etc.

 

you found a good one

 

Hi PriusCamper, can you give more information about the 100$ ebay's battery and installation ? I need to change my 12V battery.

thank you

 

Here's the link to the 12v: https://ebay.us/vN4JsP

As for installation, the battery is slightly taller, so I rebend the hold down bar across the top of it, but you could also do this by adding a longer bolt to where it mounts in front of the battery, or by modifying or removing the metal tray the battery sits on top of.

The existing terminals work fine on this battery as long as you buy the longer bolts below and sandwich the terminal between two washers that are slightly larger than each terminal:

 

I always get original Yuasa or Toyota battery. They last much longer 7-9 years in the past. I heard yellow top Optima works too but not as good as Yuasa in long terms. For 3-6 years it may work fine and cheaper.

This is the reading of my 12V battery in 3rd Gen Prius 2015 original. Without load 11.9, under load/headlight 11.3, full load heater, blower defroster 10.8 V, outside temperature 5C.
I have smart keys, never have any problems since 6 years ago with original battery. I won't spend money on something still good.

I don't believe chinese 12V battery that claims high capacity, etc. We don't trust them and they don't last as long as typical generic 12V battery. We still need AGM because it is on the trunk and next to passanger and HV battery

 

you should probably carry a jump pack if travelling beyond your 'car won't start' comfort zone

 

In need of a non smart key battery asap...been back ordered with not ETA from toyota for weeks. How can I be sure this will not be too powerful for my non smart key model as I ruined my HV battery with a wrong battery from Oreilly auto parts before. I would like to know what hardware I need to buy as well. Thank you

 

you can't have a 'too powerful' 12v battery, as only the voltage matters.

can you tell us more about your o'reilly experience? something seems off

 

apparently there is a difference between the smart key and non smart key battery requirement. From what I understand the non smart key require less cranking amps/amp hours. I went through 3 of the smart key batteries and fried my HV battery. Been using a charger every day for 3 months and I am over that process. Just trying to find a correct battery now that the OEM battery is on back order with no ETA available. OEM is a 20 HR 35 Ah with 272 CCA but nowhere to be found. Thank you

 

I did find this one locally. it has much higher cranking amps than the 272 of my OEM battery as well as higher Ah's too. Just don't want to repeat my last debacle and damage my HV battery with too much extra power because of my non smart key model.