Dead battery twice in two weeks.

You could get a solar charger and hook it up to the battery and put the solar panel in the
rear/hatch window. Since you don't drive much, this will keep a trickle charge on the battery.
And you won't have to plug it in.

 

Yes, however, if this is the parameters of usage....

I still think with a healthy, new 12 volt battery, it should be fine, and reliable. Even if the Prius goes days in between being driven.

I'm NOT against the idea or application of a battery minder, but I just think the first step should be replacing the 12 volt. If AAA has had to be called twice in two weeks for a dead battery like situation, then the immediate problem is not the absence of a battery charger, the immediate problem is the 12 volt battery itself.

I think the order of approach should be battery replacement first, and then perhaps investigation and application of battery minding.
But actually if we are talking "Days" in between driving? I would expect a healthy battery to be able to sustain operation for quite a period of time.
The OP isn't saying weeks in between driving the Prius. And the Prius 12 volt is not recharged through operation by an alternator, as the Prius does not have an alternator.
From what I can glean from the internet -operation at least once every 4 weeks should support a healthy 12 volt battery, even if not optimal. So I'd assume....speculate that a brand new healthy 12 volt, being used every couple of days, would be fine.

However, if the OP is retired-driving infrequently, and concerned about having his 12 volt ready , I'm not against adding a battery minding charger to the equation of ownership.
I just think you need to replace the failing 12 volt first, maybe determine if there is a peripheral problem, then worry about how you want to maintain the 12 volt once it is parked.

 

A VW dealership nearby us was doing that, with all the cars on their lot. Seemed sensible. I don't think they're doing it anymore though; not sure why.

 

What if it’s garaged?

 

My two cents....

Just in case you don't know, the key fob has a button that releases a hard key, which can manually unlock the driver's door, no 12v needed. So a dead battery will not cause you to be locked out.

Since you replaced it just a couple years ago, it would be premature battery failure, but that is my guess. Maybe the battery they put in was very old or maybe it just died an early death.

You can nurse this battery along with a battery tender and the hassle of remembering to plug it in every day, but eventually you will probably run into this problem again. Plus, do you really want to lug the battery tender along when you go on trips, etc.? At the end of the day, you still have a battery that appears to be compromised and may cause problems in the future at an inconvenient time/place.

You can pickup a new battery for around $100+ bucks and replacement is very simple by following YouTube videos. Takes about 15 min and a 10 mm wrench. Or for added peace of mind, the dealer's charge you mentioned of $200 is almost reasonable, if that includes battery and labor, out the door. Once you have a new battery, you know that you are good for another three to five years or so, no further thought required.

Again, just my two cents -- good luck!

 

Is your key fob(s) in near proximity of where the car is parked by any chance? That could cause an additional drain since the car thinks you are approaching it.

 

I read the first post and see that it is in a garage. The solar would work if he can place it near a window.
If there isn't a window, then a plug in charge would be the choice.
I would think it would be best to do a good test on the battery to see if it's defective. It is probably still
under a warranty, pro rated at least to off set the cost of a new one if it's bad.

 

I'm sure they passed on the cost to the customer.
The dealerships I worked at had the sales people start the cars every week.

 

Back story on why I was asking about where your fobs were.

One of my co-workers had a Gen2 Prius. Bought it used from his wife's parents. Had only one key fob - the second one got lost with the previous owner. His 12v kept failing, despite testing good, and was only 4 years old. His fob had new batteries. He asked me why the 12v might be failing and I told him to keep the fob at least 30 feet away from his car, or to keep the fob encased in something metal. He did that. 12v kept failing.

A month later he was cleaning out his car and found the lost second fob in the back of the glove compartment. It had been keeping the car's computers on full standby the entire time. Removing the lost 2rd fob solved the problem.

 

What kind of battery (brand and model) was used as the replacement?
How tight are the connection to the battery?
Are the posts clean?
Do you ever use the car and do 50 mile runs?
Any unusual warning lights on the dash?

The next time you get it jumped, run it for 30 miles (not idling in the driveway but running at 30 MPH plus) and test the voltage when you get back. Then test 4 hours later. 24 hours later.

It is either a charging circuit, a cable/connection or the battery.