2014 Prius not starting below 10 degrees, recommendation cca battery?

I do not think the 12 volt battery actually turns the engine over because the engine is started by the massive traction battery in middle of the car. The 12 volt signals the traction battery to start the car.

But if car starts when you jump start the 12 volt battery then something is funky with the 12 volt battery or the 12 volt cables. Get a good prius mechanic OR since you are in farm country attach two 12 volt cable attached one to positive one to negative terminal and run them to back seat area BUT this is a bit risky and you could jump start car from back seat. When spring comes problem is solved.

Also there should be some 12 volt terminals under the hood you can access

 

you might have a phantom drain overnight. maybe by the time you drive to a place to test it, it has recharged to some extent.
get a volt meter, and test it in the evening and morning connected to the car, and then disconnected as well, to see if it is draining on it's own.
what battery, and what is the warranty?
no, a more powerful battery won't help.

 

is 20 miles a lot for you? do you normally drive only a few miles day to day?

that can contribute to low voltage

 

This.

OP: Something is killing your 12v overnight. More CCA means nothing to a Prius since the traction battery is what provides the power to "start" the engine. The 12v only boots up and preps a few things.

 

reply:

 

Yeah, either something draining the battery overnight, or a flaky connections? The latter would yield a battery that tests good, but has troubles at start up.

 

20 miles / minutes won't add all that much charge. Being hooked up to a battery charger or tender all night should be much better.

Something else is wrong if hooking up to the under-hood jump point isn't sufficient.

The 12V also charges the brake accumulator before the car is even started, requiring a burst much more than simply booting up some computers, but still far less than the typical non-hybrid electric starter.

 

I think it's something like 50A for several seconds so you're right in saying it's much less than non-hybrids.

 

[QUOTE="fuzzy1, post: 3226685, member: 48224"
The 12V also charges the brake accumulator before the car is even started, requiring a burst much more than simply booting up some computers, but still far less than the typical non-hybrid electric starter.[/QUOTE]

Hence the "prep" a few things part of my comment.

I think there's a chart that someone made floating around that measured the load over time on the 12v system from door open to engine start. I found it interesting.

 

quote:

 

How old is the battery, 1 year?? Maybe it is defective, in the FROZEN climate, that's hard on a battery.
If you put it on a charger overnight, 4 amps or less, charge the battery overnight. After disconnecting the
charger, give it aout 15 minutes to cool off and stablize. Maybe the battery wasn't fully charged when you got it.
That seems to be a common issue. They sit on the selves for months.