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Ron3rd's avatar
Ron3rd
Explorer III
Sep 15, 2018

What if you wire 12v water pump backwards?

I have a little portable 12v RV water pump (similar to Shurflo but not that brand). The other day, I was using it, it worked fine, but I discovered the polarity on the 12v wires was backwards. So I reversed the wires to correct the problem and it still worked fine. Could there be any damage done by having it wired backwards? Does polarity matter?
  • Ron3rd's avatar
    Ron3rd
    Explorer III
    Thanks for the info folks. I was just wondering if I did any damage having it wired backwards. Seems to work fine!

    BTW, I checked the brand and it's SEAFLO
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    DC motors come in a couple of flavors.. On one reverse the wires and it runs backwards.. This MIGHT cause damage (permenate magnet type)

    On another reverse the wires and .. it don't work period (no damge) (Brushless like 12 volt comptuer fans)

    On the 3rd. (ELectro magnet) it works fine no damage.

    You clearly have type 3 or what follows:

    I notice you said "PUMP".. There is also a different type of pump that does not actually have a motor. but a spring, disprham and electro magenet.. This works as follows

    A magnet pulls a rod (Solenoid type magnet/rod) up compressing a spring and sucking in whatever is being pumped via a check valve.
    Then the magnet lets go and the spring pushes it out via another check valve.

    This is also works no matter which wire is which without damage.
  • Would probably suck the water out of the shower and put it back in the fresh tank...:B :R

    Housted
  • The wires on the pump, were black and red on the exact replacement pump in our Mh.
    Simply unplugged, and plugged in the new one. Red positive. Black negative.
  • Same as hooking a horn up backwards...it sucks instead of blows.
  • DC MOTOR can turn either direction W/O ANY damage

    What the motor is turning CAN be damaged from 'wrong' rotation

    RV water is a diaphragm pump...diaphragms just move back/forth so direction of motor does NOT matter

    No harm/no foul :B
  • It depends on the model. Some have electronic control circuitry and that may or may not be protected from reverse polarity. Simple pumps would just run backwards without damage.
    But if it still works, it's OK!

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