Prius III 2010

Not that easy to get to. It's in the back. But, one can easily access charging terminals in the front of the car, in where the fuses are kept. I think it's in your manual.

 

My manual says it is on the passenger side under the storage inside a box by the spare tire.

 

Under the removable, right side panel. Your manual will show this.

 

Let's get a step by step going here!
1) remove the cargo mat
2) remove the cover from the under-floor storage box
3) lift the storage box up & out. You'll see the spare tire and tire changine equipment.
4) on the right side of the car, there's a box/ panel that looks like trim. Pick it straight up and you'll see the battery.

As previously stated, there's a 12 voult charge port under the hood on the driver's side. Should your Prius require a jump start...follow these steps.

1) Pull the hod latch located under the dash board on the driver's side of the car.
2) Open the safety release located in front of the car. Stick your hand under the hood, just to the right of the Toyota emblem.
3) support the hood with the prop rod
4) Locate the fuse & relay box on the driver's side of the car. It's black and is right next to the fender.
5) Open the box by pushing the release button located on the front of the box ( The front is twords the front bumper of the car. Push the button & pull straight up on the cover. It's tricky to remove but be patient & gentle. Little force is required to open this box.
6) Once open, locate the Red cover and open it. That terminal is the 12 volt positive terminal and is used to jump start the car.
The ground terminal is on the left side of the car. It's a black painted metal bar that sticks straigt up left of the engine. That's where you're supposed to pick the negative or black jumper cable.