1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Water Pump 12V Connection

Discussion in 'Gen 3 Prius Accessories and Modifications' started by andreimontreal, Feb 6, 2019.

  1. andreimontreal

    andreimontreal Active Member

    Joined:
    Jan 30, 2019
    326
    107
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    Can I hook a 12V water pump directly to the 12V small car battery?

    I want to do a VanLife mini conversion out of my Prius. I'm installing this water jug with a 12V water pump and a faucet. The pump won't be used more than 1min/day at most, ever. It has a diaphragm switch (when the faucet is off, the pressure in the pipe shuts off the pump) but I will insert a on/off electrical switch for added security.

    Do you see any risk? It seem to me the power draw is so small I shouldn't even worry about it. I'm avoiding the cigarette lighter plug because I want to be able to run the pump with the car is off.

    Andrei
     
  2. tankyuong

    tankyuong Senior Member

    Joined:
    Nov 9, 2012
    1,555
    660
    0
    Location:
    Central MO
    Vehicle:
    2012 Prius c
    Model:
    II
    Should be fine
     
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,921
    15,551
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Be sure to consider fusing when attaching directly to the battery. Small as it is, the battery is more than capable of using your added wiring to start fires, especially if you use fairly light-gauge wire because your added accessory doesn't need it heavy.

    You want something that will interrupt the current as close to the battery as possible, in case of damage to your wiring.

    Here's the strategy I use:

    If you look at the car's positive cable connection to your battery post, there is a heavy fuse link (rated 120 amps or so) built into it. Make your tap from the car side of that fuse, not the battery-post side. (You can unclip the plastic cover that goes over that clamp connection and fuse. At the bottom of the part that goes down alongside the battery case, there is a bolted connection. Make a wire with a ring terminal and attach it there at the bolt. Now your connection is protected from the battery by the car's high-current fuse.)

    The next step is to supply your own fuse, as near to that tap as possible, where your fuse's ampacity is chosen according to what your accessory actually needs, and what the wire you will be running to the accessory can handle. In the final picture, your added device and wiring is protected by the fuse you add. That can be one of the small, cheap kinds of fuse, because it in turn is protected from worst-case short-circuit currents by the heavy fuse link that's upstream of it.
     
  4. andreimontreal

    andreimontreal Active Member

    Joined:
    Jan 30, 2019
    326
    107
    28
    Location:
    Montreal
    Vehicle:
    2012 Prius
    Model:
    N/A
    Thanks for the answers. Nice tip ChapmanF, I did not think of the potential fire hazard, I'll probably add a fuse like you say. The on/off switch would cut off the power most of the time and I would turn it on when I want to run the tap - but still - it never hurts to be extra-safe.

    Andrei