Battery keeps dying in cold weather

Probably needs a new 12v battery. At the very least get it tested. Lots of neighborhood autopart stores can do that for you.

 

Yes, it is related to the 12v battery. How old is the battery? If it is more than 5 years old, you should get the battery tested at an auto parts store like Autozone, NAPA, etc.

Short drives a few times a week are not enough to change the 12v battery. You can buy a smart charger and connect it to the battery in the back OR in the fuse box under the hood in the front. I use a NOCO brand smart charger for this purpose.

If you do not have access to 120v for the charger, you can leave the car turned on for 6 to 8 hours at a time once every week or two. The hybrid battery will slowly change the 12v battery. You will be using gas during this process, and your car could be stolen.

Posted via the PriusChat mobile app.

 

Toyota's don't charge their 12v very well when you drive it. You need to buy a smart charger that goes up to at least 8 amps if you want to stop this problem from happening, which is common with older 12v in a Prius that isn't being driven very often. Find one that costs $30 or less like this one: https://www.ebay.com/itm/175344258209

 

i just got this one:

B07W46BX31

 

Just make sure to get one that is not just cheap but comes in a desktop style box with a fan inside... The most popular ones cost twice as much or more and are built into the power cord it comes with and has no fan to keep the system cool. To make up for the lack of fan they limit the power output of the system, which means it takes way longer to charge a thoroughly drained battery.

 

You bought a junk charger that can't even put out more than 1 amp even thought a 8-10amp smart charger costs the same price? Next time you're waiting all day for your 12v to recharge I hope you think about my opinion of your charger...

 

i don't use it to charge the battery drom dead, just to maintain it between drives, which is what the o/p needs.
please post a link for anyone interested

 

I use the same one for my 4Runner, which sits 2 or 3 weeks between drives. I have it connected 24/7 to the 4Runner battery when it is not being driven.

Posted via the PriusChat mobile app.

 

Toyota only recommends a 4 amp maximum charger be used for the Prius 12v battery.

Posted via the PriusChat mobile app.

 

I use a Battery Tender Jr which is widely available even at Walmart and Ace Hardware in addition to online. It has a nice quick connect cable that allows a portion of it to be permanently connected to your battery. Will not overcharge or reverse polarity your car. About $35.

 

Sending a 4amp constant load with a dumb charger is a bad idea by every measure.

A smart charger only pumps out as many amps as the 12v is ready to handle... This is especially valuable with a 12v that's super drained or near fully charged, which is when a 12volts performance is particularly vulnerable to sending it the wrong amount of amps...

 

I use and 8Amp Schumacher wal mart . I have made a plug that I've attached to the Prius battery and have that plug essentially laying on top of the piece of carpeted plastic and it just lays there with a plastic cover on it all the time when I want to put the eight amp battery charger tender to the car I open the trunk connect the charger run the cord out close the trunk The charger will charge the battery from zero to eight amps by the internal chip in the charger that's reading the battery as the battery gets closer and closer to charged It pulls the amps back when the battery reaches charge the yellow light turns green and the maintainer takes over which I think won't go over one amp in the maintaining mode and this goes on as long as it's plugged up. In the morning when I walk out to the car I need to be remembering to unplug the charger from the 120 volts It could be left plugged into the car but you don't want to forget and be dragging an extension cord down your road and this can be difficult for folks to do people leave their kids in car seats next to the car and drive off I can imagine a battery charger My setup is similar to an electric car there's a little stand in my driveway that's a charger sits under to keep it out of the weather and the cord goes to the car and it's painted a bright pink so you can't miss it there's even a little light that sits next to the little roof that's over my little charging station that looks like a mailbox so that when I walk out to the car when it's dark that light is on right next to the charger lighting up that pink cord and the receptacle end of the cord is lit up in orange indicating that it has power and I know I need to remove that before I get in a hurry and try to break camp too fast.

 

Sounds like a lot of work

 

I just have a large cardboard sign attached to the steering wheel:

DISCONNECT BATTERY CHARGER!

 

YES.
You need to find some way to keep the 12 V battery charged up when not in use.
First you probably need a new fully charged battery.

 

99.99% of car owners never have a real need for a charger with an 8 amp capacity.
4 is plenty.
THEN.....the price for that model is too low to be true. Likely something fishy is going on.