Problem Water Pump

[MattM]

My water pump works great under battery power. When switched to city power, the pump runs like mad but does not pump any water. My first thought was the fuses, but after the squirrel in my head got tired of running on its wheel, he yelled at me that the pump is running because of the noise it's making and it can't be the fuses.



Now the squirrel tells me not to worry because if I'm camping with city power, most likely I will have city water and don't need the pump. However, I do like to have all options open in case of unusual conditions, and I figure there is a selector switch for a reason. Any suggestions will be welcome.

[RichardT]

There is something missing from the equation here.

Assuming your pump is a typical 12 volt water pump it should be running on 12 volts regardless of power source. So the fact that it works on Battery power but not on City power makes no sense. When on city power the pump would still be operating off of the 12 volt system.

Are you leaving anything out of your question?

[azflycaster]

I would verify the polarity of the city power and/or the city power cable on your TT. If this is reveresed it could cause your water pump to run backwards. It can also cause damage to other devices.

[Loren]

Originally Posted by azflycaster

I would verify the polarity of the city power and/or the city power cable on your TT. If this is reveresed it could cause your water pump to run backwards. It can also cause damage to other devices.

This is a joke, right?

Yes, there is such a thing as polarity to AC power, but it has to do with which wire is attached to the hot side and which wire is attached to ground at the power panel. It has nothing to do with polarity as used in discussions of DC power.

There is no way to hook up AC power to your trailer that can cause your DC power to reverse its polarity. Even if the AC receptacle has incorrect polarity, the DC converter will still produce proper DC.
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Matt,

I also don't understand how this could possibly happen. Your pump is getting DC one way or the other, either from the batteries or from the converter and batteries. The only difference is that when you are plugged into shore power, your DC voltage is probably a bit higher. I don't see how that could cause your problem. Sorry.

Loren