DC inline fuse blows when battery power turned on

If it just started when you replaced the battery, odds are you hooked it up wrong.

Are you sure that is a negative cable? Not sure why there would be a fuse there except maybe reverse polarity protection but have never seen it done that way. Trace the wire to the frame and make sure positive and negative are correct.

baseball wrote:
Anyway, when I go to turn on the DC power to trailer, it blows the inline 30 amp fuse. it is located on the negative side of battery.

It's not a fuse but a circuit breaker, usually auto resetting, and it should be in the positive cable coming from the battery. Sure sounds like you've connected the battery backwards.

Fuse is typically on a heavy black wire to the positive battery terminal.
Main negative connection is usually white and connects to the frame.

thanks Chris. i swapped them and now no blown fuse, but still no power to cabin. I went to fuse box and checked the two 30a fuses located at top of what i will call the DC distribution panel. no issues. the negative from battery connects to top left terminal on panel. the positive comes in and leaves on white wire from battery on top right. Right beside it is a red wire which the panel says is the positive from converter. when i put meter on the white and black terminals, there was not power. Could this be a bad converter??

Check the converter is getting 120vac in and should produce 13.5 vdc out.
Although if the battery is charged you should have 12.5+ volts in the DC fuse panel.

ok. more info. i do not have any shore power to trailer. and the white negative is not connected to frame. it goes into a cover in the passthur space at from of cabin. taking cover off, there multiple wires connected via wire nut to the negative. if it is connected to frame, it must be somewhere back towards the rear. there is nothing close to the tongue.

"the positive comes in and leaves on white wire from battery on top right."

White is negative!

Get a multimeter and check which is positive and which is negative all the way through so you will know. Makes no difference what the wire color is.

Ignore wire color, there are too many "standards," and none of them are standard. Trace BOTH wires from the battery. ONE of them should go to the frame. THAT is the negative cable.

I have never, ever, seen a negative cable with a fuse or circuit breaker on it. I would bet money that the cable withOUT the fuse or circuit breaker is your negative cable.