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

MNtundraRet wrote:
Replacing the two 6v batteries (220 amps) with one 12v battery (65 to 85 amps) is going to be a mistake.
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But I don't want the expense, weight and maintenance of two six volt batteries. I also don't need the reserve capacity. Also, the two six volt batteries were considerably larger and did not fit properly on the tongue because it was built for one 24/27 series battery box. I don't see the benefit of two six volt batteries for a camper that is for sale and only came with one 12-volt battery. Seems like an unnecessary expense and liability for no gain, unless of course selling it would be much quicker and/or bring a much higher sale price.

I can't understand this thread at all. He said it worked on battery (no shore power) and now supposedly after he charged the battery, it still works. Only now it also works on shore power.

So why did his converter 12v blow the fuse before? It should run it all with no battery--who cares if it is just low? But it worked with no shore power, so the battery was ok anyway.

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

Fellows some of you need to ahem....
brush up on electrical theory

The lower the voltage in direct current, the less the amperage. DC does not have a variable Power Factor.

The HIGHER the voltage the more amperage flows through a resistance.

Check your voltage with the rig plugged in, and converter charging the battery.

A BORDERLINE pump electrical short within the pump or clogged pump can easily cross the fused threshold and fail the fuse if voltage is raised by 2-volts.

Time to run the pump for 2-minutes with the sink tap wide open, shut off the pump then -carefully-feel the outside of the pump looking for hot spots. A bad intermediate bearing between motor and pump can cause a pump to run borderline on amperage.

Replacing the two 6v batteries (220 amps) with one 12v battery (65 to 85 amps) is going to be a mistake. One 12 volt battery will need more time to fully recharge than the 6v pair of batteries.

It sounds like you have not kept the battery on shore-power long enough to fully recharge (24 to 48 hours). Have you used the "disconnect" switch to make sure the battery when fully charged does not lose charge due to detectors, CPUs in equipment, etc. drawing current while stored.

Having a smaller battery-bank can easily deplete the battery if you forget to disconnect when stored. If leaving plugged in all the time, be prepared to check the battery cells for lost fluid.

That's funny. I told the wife I thought the same thing, theoretically, could happen (not knowing any different) and I was going to see if leaving the shore power hooked up to charge the battery made a difference. It did. Works fine now. Thanks for all your help.

sljkansas wrote:
The water pump operates only on 12vdc. Shore power is 120 volts AC. If your trailer battery is low on charge the pump will pull more current and may blow the fuse.

X 2

The water pump operates only on 12vdc. Shore power is 120 volts AC. If your trailer battery is low on charge the pump will pull more current and may blow the fuse.

Does your rig have multiple momentary switches to operate the pump?
It could be the "pump controller" causing the issue.
Corroded connection could increase resistance and over load the fuse.
Check the converter output voltage.