I need to attach a 12V device in my 2012 Prius, but in the engine compartment rather than at the auxiliary battery in the back. I understand that for jump starting, there is a positive terminal in the front fuse box and that the negative should should be attached to the engine block. But does this also provide 12V power? Unfortunately I need the power all the time, not just when the ignition is on. Is there any possibility of doing this?
Yes, but you’ll probably drain the 12V, it’s not designed for 24 hour use. The battery only supplies the 12-14.5 volts temporarily to initiate “ready” Its a totally different battery with about a 38 ampere rating.
There are two good options for 12v constant power available in the engine fuse box. In the picture, there are two open terminals at the back of the fuse box, seen with two push on connectors with red wires. In addition, at the front corner of the fuse box, there is a bolt that you can put a ring terminal under, seen here in the picture with the cover opened, it's the 10mm bolt to the right of the heavy gauge white wire, just below the small screwdriver. Posted via the PriusChat mobile app.
@NutzAboutBolts Video #23 here: Nutz About Bolts Prius Maintenance Videos | PriusChat Shows how to access the 12 volt connection point, basically to piggy back a spade/ring connector. You'll likely need to bend the connector at its shoulder; space is tight.
