12 volt battery ?

You can jump the car from under the hood, following the instructions in the manual. You only need to get the system started then you can pull out to access the battery. Or, just replace the battery now to avoid trouble.

 

You'll likely have some warning signs before the battery dies enough to not start the car. If you're really worried about it, I would check the battery voltage after the car has been sitting for several hours every month or two.

 

When the 12V battery finally does die, access to the power "boost point" is under the hood, so you're good. It's more difficult to get to the battery as the hatch release is electric. There is a manual hatch release but you have to crawl over the back seat and lift the hatch floor to get at it.

 

Use a battery maintainer while parking in the garage. I have a genius 3500, very easy to install and use it.

 

Someone here posted a neat tip on how to tell if the 12 volt battery is dying. Put the car in accessory mode after it's been sitting overnight and try the driver's power window. Does it seem sluggish or slower than when the car is in Ready mode? Time to replace the battery.

 

This is only sound tip IF the car had been running (being in Ready) for well over an hour before that over night sitting. A fairly discharge 12 V prius battery takes quite a long time to be fully charged (due to a very low charging current ). Just a few short trip can quite a bit discharge the battery.

Of course the battery could be charged with an appropriate battery charger as well again max 4 A is recommended el-chepo conventional (older) charger can damage the battery. And then this test maybe usefull.