charging 12V battery in winter time

Will she drive the car almost every day? That is really unnecessary in my opinion. I've had no problems in the winter at all over the last four winters in my car, and I'm really close to you...

 

I hook up a "smart" charger, at the under-the-hood jump start conection, just every once in a while, maybe 3~4 times per year.

The one I have is CTEK 3300, kind of pricey, but good quality construction, and has rudimentary indicator light that indicate when it's charging (orange), and when it's satisfied the battery is fully charged (green). It can be set to various levels (motorcycle, vehicle, vehicle-in extreme cold). It's max charging rate is a modest 3.3 amp maximum.

It's the kind of charger that goes through a cycle of charging, ending up with just a trickle charge. It can be left on indefinitely, say if you're going on vacation.

There's info on CTEK here:

Buy Battery Chargers | CTEK Battery Chargers Multi US 3300

(I see they've got some new toys: the 4.3 looks interesting)

 

Basically, all the 12-volt does is power accessories. The battery-pack is what turns over the engine, which is specially optimized for easy starts.

This winter will be my 13th with a Prius in Minnesota. Never has there been a concern about starting, even when it sits out all day in temperatures below 0°F (-18°C).

From time to time, you'll want to run a long errand to keep the car in good health. But that's true of any vehicle. Short drives are hard on them even in the summer. Fortunately, Prius startups require much less demand on the 12-volt.

 

There are a lot of portable 12 volt packs for emergency start. I picked up one when I needed to periodically start a car we were storing, that had a dead battery. I started off using jumper cable with our previous Honda Civic Hybrid, but read that it was too much wear-and-tear on our car's diminutive 12 volt, so picked up a Jump-n-Carry JNC660:

http://www.cloreautomotive.com/sku.php?id=244

One gotcha with this model: you have to be careful when rewrapping the cables, the clamps can chew into the cable insulation if mis-wound.

It's very handy, actually needed it last weekend: my son had left a map light on and nearly killed his battery. This got him going, and an overnight hook-up of the previously mentioned CTEK got it fully re-charged.

Again, there's a lot of similar products out there, some lighter duty, some heavier.

 

Lithium batteries are much more dangerous than others even though they are good for high energy storage in a small package. Fire is the big problem and could happen while charging or discharging. I would buy a standard jump starter package and try to remember to keep it charged since you could go years without needing it. The big problem is discharging the standard 12v by leaving the rear hatch light on. Link to battery safety Radical RC

 

Is the Prius 12 volt battery lithium?

 

The 12-volt is an ordinary lead-acid type.

No special handling or care is needed.

 

I had a similar concern when I was driving only once every few weeks. I added a solar battery maintainer ( a couple of watts) that sits in the back window. It puts out just enough power to take care of the drain from all of the accessories.

Does it work? I'd say it does. The battery is now 10 years old and I'm just now seeing signs that it might be time to replace it. I logged in here to see if there were any new sources for a replacement.

Dan

 

I've never heard of anyone having problems by leaving their Prius v set for two weeks or less. I think I read that Toyota recommends a battery charger if the car sets for a month or more. Between two weeks and a month is a gray area, but I doubt you'd need a battery charger for that. In your case, if you wife drives the car a short distance every day, that should be more than enough to keep the battery charged. Somewhere in the user's manual is a list of the voltages you can expect for various battery conditions. You take the car for a short drive, then shut it off and leave it set for 20 to 30 minutes, and then you measure the battery's voltage. The chart in the user's manual then tells you the condition of the battery. So, if you are concerned about the ability to keep your battery fully charged, doing that test should give you peace of mind. If you decide to put the battery on a charger, I'd recommend making the connection under the hood (as has already been suggested) rather than at the battery in the back of the car. With the hood up, you are less likely to jump into the car and drive off, pulling the battery charger and its wires after you.

 

I went to an open house at my dealer a month ago and specifically asked about battery chargers and leaving the car idle for periods of time. The service tech told me that nothing is necessary if you leave the car idle for a month or less. Any more than that, he said, use a Battery Tender (brand), not a battery charger.