Water Pump - 12V works, 110V blows a fuse

The reason it works fine now is because the converter is no longer charging the battery. Run the battery down some and try again while the converter is in charge mode, and the problem will return.

The pump is getting dodgy. You'll have to determine for yourself if replacing the pump is worth it.

Like trying to read Sanskrit...

"but everything works fine now."

So self-correction. End of issue....

Nope, inline fuse solely for the pump, but everything works fine now.

Ace! wrote:
I put the two six volts when I was boondocking, a few years ago (or more). They needed to be replaced so I decided to go back to one 12V, which the "new" owner will better understand. I had just put the (one) battery on the trailer and started to see how stuff worked.

When I turned on the refrigerator the fan came on for the converter (overload/overheat fan). That's also when the fuse for the pump blew. If I unplugged the shore power everything in the trailer worked fine. After a few hours of leaving the popup hooked to shore power (charging the battery), everything worked on shore power, including the water pump.

I can see how a 12v fridge might cause the converter to run hard but not run so hard when the batts are charged up to help run the fridge. Not many fridges are 12v anymore though. Most now just need a little 12v to run the controls and propane burner.

Is the 10a fuse that blew also to do with the fridge somehow? Fridge plus water pump too many amps? This all may have nothing to do with the water pump itself.

Just guessing. No idea what is actually going on there.

The pump could have some type of restriction in the lines that requires the pump to work harder. Could be debris in the faucet aerators.

A 7A RV water pump blowing a 10A fuse sounds like the pump is going, but it ain't gonna be your problem once it leaves the drive way !

I put the two six volts when I was boondocking, a few years ago (or more). They needed to be replaced so I decided to go back to one 12V, which the "new" owner will better understand. I had just put the (one) battery on the trailer and started to see how stuff worked.

When I turned on the refrigerator the fan came on for the converter (overload/overheat fan). That's also when the fuse for the pump blew. If I unplugged the shore power everything in the trailer worked fine. After a few hours of leaving the popup hooked to shore power (charging the battery), everything worked on shore power, including the water pump.

An RV battery delivers what, 12.4 - 12.5 volts under an 8-amp water pump pressure build-up.

The voltage difference 12.4 - 14.4 absorbsion limit is TWO FULL VOLTS. Divide 14.4 into 12.4

How much percentage GAIN is there with using higher voltage?

This deserves troubleshooting with an inductive ammeter. The pump may be sick.

Find the cause soon and perhaps the pump can be successfully repaired. Find it later and guaranteed a new pump will be required. After a waterless outing.

BFL13 wrote:

This is not over IMO---why did that fuse blow?

Mex explained it but not enough info, what if it was blowing when the WFCO actually was doing 14+ and didn't blow at 13.6 or batt v?

Sorry. I missed the fact you had a popup trailer. You might have a wire somewhere in the charging circuit that may be frayed and shorting causing the fuse to blow.

And one battery should be enough for your trailer. It sounds like the previous owner set up the trailer for two batteries. Wires going through the trailer walls may have frayed if a proper grommet was not installed to protect them.