Prius C 2015 - very little to know usage/maintenance inquiry

Well, the hybrid batteries tend to go bad with age whether you use them or not, and they typically cost a few thousand bucks to replace. Letting the car sit could be seen an an expensive choice vs. selling it off and buying again when it is time to drive more.

So there is that drawback to letting the car sit.

Now as far as the 12v battery goes, the one that just boots the car up into READY mode? those are obviously a lot cheaper, but they need frequent usage or supplementary charging in order to work. They can die to the point where a jump won't work but is rare outside of subzero temps, and the particulars of what you're using to do the jump. Some jump-start packs have a reverse polarity protection feature (which is nice) but if the target battery is absolutely dead it'll fake out the jump pack and you don't get a start. Others have an override system- if you know how to use it.

Does your parking arrangement include any sunlight? You could install a solar battery tender, just to keep that 12v unit topped up from one trip to the next. You'd just have the panel on your dashboard or suction-cupped onto a window.

After that it's the less convenient stuff, like removing the 12v battery from the car and putting it on a maintenance charger in your living space.

 

It's not that it runs down faster; it's mostly that it has different consequences. If the hybrid battery is allowed to rest long enough to fully discharge, there is no easy recovery path. Toyota will tow it in and charge you a few thousand bucks to replace it. Experienced hybrid mechanics (and DIYers) have a few cheaper tricks to get out of that jam, but it's still not a good situation.

The real answer is to put the 12v battery back in there and use the car for a few hours every 3-4 months.

Even with regular usage, the hybrid battery in the c seems to last "around 10 years." So it's possible you might be carefully storing this thing until the moment when it needs an expensive replacement anyway.

Don't forget to use gasoline stabilizer as well.

A hybrid is a little bit like getting an ice cream cone while walking through a park on a hot day: you don't have to eat the ice cream, but there's no such thing as saving it for later.