Live circuits after pulling fuses from converter

[NavyLCDR]

Originally Posted by bubbles

OK. I yield. This was my reasoning for the assumption from WFCO 8900 manual and assumed the OP's WFCO would be the same:

Reverse Battery Protection
The WF-8900 Series Power Centers will charge the 12-volt House battery if installed. A battery DOES NOT have to be installed for WF-8900 Series Power Center converter operation. When a battery is installed, two reverse polarity fuses protect the converter circuitry. The fuses are located along the left-center edge of the DC fuse board below the VCC+ lug. Refer to Figure 1 below. This feature prevents permanent damage to the converter from a battery connected into the circuit backwards. In addition to protecting the converter section, the reverse polarity fuses are the main connection between the converter and the DC fuse board.

The OP's WFCO should be the same. The last sentence says "In addition to protecting the converter section, the reverse polarity fuses are the main connection between the converter and the DC fuse board." If you pull the reverse polarity fuses, the battery is supposed to be completely disconnected from the fuse board. If the converter has AC power, then the DC output from the converter will supply power to the loads through the branch fuses. Pull the branch fuse and that circuit should go dead in all cases regardless of what source is supplying power to the DC fuse board.

The fact that the OP has power on all circuits even with their branch fuses pulled indicates a serious error in wiring somewhere.

[Sammici]

Thanks everyone for all the input. I'll be pulling out the converter later today to look for any shorts or other issue.
I've gone over all my connections in my recent upgrades to solar/battery and it all looks good. Only positive and negative wire connects to my setup. Same as when first purchased.
Something tells me it's in the converter.
Pulling the reverse fuse has no effect, go figure.

[Larry-NC]

Originally Posted by bubbles

OK. I yield. This was my reasoning for the assumption from WFCO 8900 manual and assumed the OP's WFCO would be the same:

Reverse Battery Protection
The WF-8900 Series Power Centers will charge the 12-volt House battery if installed. A battery DOES NOT have to be installed for WF-8900 Series Power Center converter operation. When a battery is installed, two reverse polarity fuses protect the converter circuitry. The fuses are located along the left-center edge of the DC fuse board below the VCC+ lug. Refer to Figure 1 below. This feature prevents permanent damage to the converter from a battery connected into the circuit backwards. In addition to protecting the converter section, the reverse polarity fuses are the main connection between the converter and the DC fuse board.

I'm pretty sure you are right, Bubbles. The black (negative) leads from the the battery and converter go to a common terminal (two screw-downs) on the fuse/distribution board. But the red leads (positive) go to two distinct terminals. The one from the battery is "+", but the one from the converter is labelled "Vcc." It looks like Vcc goes through the reverse polarity fuses (Note plural) before connecting to "+" and the fuses. I've got a spare WFCO 8955 distribution board here and can post a photo if desired.

[bubbles]

Originally Posted by Larry-NC

I'm pretty sure you are right, Bubbles. The black (negative) leads from the the battery and converter go to a common terminal (two screw-downs) on the fuse/distribution board. But the red leads (positive) go to two distinct terminals. The one from the battery is "+", but the one from the converter is labelled "Vcc." It looks like Vcc goes through the reverse polarity fuses (Note plural) before connecting to "+" and the fuses. I've got a spare WFCO 8955 distribution board here and can post a photo if desired.

Thanks, I don't need a photo.

[Larry-NC]

Originally Posted by TacomaJoe

I love a mystery. Can't imagine what is happening. Even if a circuit was back fed, it would be able to jump to the other circuits with the fuses pulled.

One thought is the definition of powered. These panels with the LED indicators for a blown fuse will measure 12VDC on the open circuit because you are getting a path through the LED.

You've got it, Joe. Every fuse is bypassed by an LED (drops about 1.5 volts) and series 330 ohm resistor. If you measure the output side of the removed fuse with a high-impedance voltmeter, it will still look like 12 volts if there is no load.

If you were to put a 330 ohm load on the circuit, the LED would light and the meter would read around 5.25 volts [ (12-1.5)/2 ]. Most of the loads in an RV (e.g., incandescent. lighting, range hood, etc.) are much lower than 330 ohms. The lower the resistance, the higher the voltage at the fuse output terminal; it could range from 5.25 volts to near 12 volts.

The OP could test this by putting a meter on the fuse output and varying the loads.

[Sergiop]

You didn’t miss one of these fuses did you?

[Larry-NC]

Originally Posted by bubbles

Thanks, I don't need a photo.

The photo offer was for the Commander's benefit.

[TitanMike]

Originally Posted by Sammici

"something is very drastically wrong with the wiring in the trailer. It is not normal, at all."

Isn't this normal for a FR product!

Just kidding. DW and I enjoy our little Palomini.
I just recently upgraded my battery and solar and mounted everything on a board.
But, I used the same exsisting black and red wire that fed back to the converter. Hence why this may have been a problem from the get go. Attachment 270753

Your upgrade certainly looks nice.

When you say you used the same existing black and red wire that fed back to the converter do you mean the wires that were originally connected to the factory battery?

Just some thoughts:

A normal operating Converter will both supply 12 vdc to the fuse board and battery to run 12 volt powered items and charge batteries. When converter is off battery continues to supply 12 volt items through the same fuses.

As Larry-NC pointed out the converter has a fuses that protect it from reverse polarity and merely carry current from Converter to fuse board and battery. Pulling these will not. when properly wired, cut power to the fuse board. There should be a wiring diagram on the inside panel of your Power Distribution Center that will show VCC terminal and + terminal. Converter power goes to one side of the reverse polarity fuses and battery power is connected to the other.

What is puzzling is that you say with all fuses pulled, I assume from the individually labeled positions, ALL 12 volt items still work. The more I think about this it's practically impossible as there is no cross connection under normal circumstances from one fuse load side to another fuse. Only common connection is on the power side which is usually just a continuous bus connected to the main 12 volt source.

Only way possible for all 12 volt loads to have power on the load side of the fuse board with all fuses pulled is for there to be a continuous "short" on the load side that connects all load terminals together. Was fuse board ever removed or dislodged?

Was everything working OK before you started checking? What sent you on this diagnostic mission?


There is supposed to be 12 volt power on the power side of the fuse board at all times the battery is connected. If the battery is disconnected then power will be there only when the converter is powered up from shore power.

Solar power should be connected directly to the battery.

Obviously none of us are there and can't see what you are seeing so we can only guess.

[DougW]

From reading through this it sounds as though the 12VDC things throughout the RV are still working even after all of the fuses were removed. If that is the case it sounds like the loads are wired to the wrong side of the fuses, the loads are on the hot side of the fuses, not the protected side.

[radiodave]

As TitanMike suggested, did the 12v system work correctly before the solar mod?

[Sammici]

As far as I know it was working properly.
What made me check was when I went to put on furnace nothing happened. I checked the fuses. I pulled out the reverse fuse and noticed that the lights stayed on. That’s what got me curious. I then started pulling other fuses and those loads also stayed on.
I just opened up the converter and visually see nothing wrong. I need to start checking the connections.
At this time I’m hesitant to plug into shore power, just in case.
Thanks all.

[radiodave]

Recommend rechecking the solar mod. Keep us posted! Good Luck!

[Sammici]

Originally Posted by radiodave

Recommend rechecking the solar mod. Keep us posted! Good Luck!

I did disconnect the solar and still had issue.

[Larry-NC]

Originally Posted by DougW

From reading through this it sounds as though the 12VDC things throughout the RV are still working even after all of the fuses were removed. If that is the case it sounds like the loads are wired to the wrong side of the fuses, the loads are on the hot side of the fuses, not the protected side.

No, Doug. As clearly stated above, wired in parallel with the fuse are an LED and series 330-ohm resistor. If you have no loads on the circuit, measuring from the output side of the fuse will reflect around 12v to ground.

As also has been stated, the "reverse-polarity" fuses only isolate the converter. The battery is still connected to the fuses.

[Sammici]

By process of elimination I have found that when I pull out fuse 1, the furnace/lp detect/water pump all the circuits die when the 30A battery fuse is out.
Now to find out why!

[NavyLCDR]

You were right, I was wrong, and I apologize for being so pig headed. I pulled my 30 amp fuses and they only disconnected the converter from the DC circuit, they did not disconnect the battery. Only the battery disconnect switch and/or the resettable circuit breaker disconnected the battery from the DC circuit.

However, as expected, the branch fuses separated that branch circuit from all sources of power when pulled.

[Sammici]

Also strange that with no fuse for furnace or battery that when I switched the thermostat for heat it turned on the blower

[NavyLCDR]

I would be looking for a transformer in the thermostat circuit.

[TitanMike]

Originally Posted by Sammici

By process of elimination I have found that when I pull out fuse 1, the furnace/lp detect/water pump all the circuits die when the 30A battery fuse is out.
Now to find out why!

There might be something here. The #1 fuse circuit is getting power directly from the battery when the 30 amp battery fuse is pulled.

With both 30 amp fuse pulled and #1 fuse also pulled, check for voltage on the #1 fuse terminals. There should be none. If you find power present on the RH fuse terminal (load side) there is a cross connect with battery + somewhere along the line. Can't say where but it will limit the possibilities.

Since the LP detector is supposed to be "Hot" all the time that may be a possibility.

Only guessing but possibly someone connected furnace and LP detector wires after the LP detector was connected to a permanent DC source.

[Larry-NC]

Originally Posted by Sammici

Also strange that with no fuse for furnace or battery that when I switched the thermostat for heat it turned on the blower

Are you SURE it wasn't the blower in the Air Conditioner?

1. The Air Conditioner runs on 120 V AC. It's controlled by a circuit breaker
2. The "Fan On/Off" switch in the thermostat controls the Air Conditioner blower, not the one in the furnace.
3. For safety reasons there IS NO DIRECT CONTROL OF THE FURNACE FAN. It goes on before the furnace ignites and stays on for 90 seconds after the furnace shuts down.

Are you aware that some of the fixtures (lighting, range hood, furnace, etc.) can run on 12 volts from the battery and can operate when you are camping with no place to plug in? The converter serves to recharge the batteries, but can also operate the fixtures if there is no battery or the 30 amp fuses are removed.

Right now you have both a charged battery and the converter feeding the 12 volt fixtures. When you disconnect just one of these, it is expected that the other source will feed them.

About the only fixtures that only operate with 120 volts when the trailer is plugged in are the air conditioner and microwave oven. Possibly the refrigerator, depending on what kind it is. The water heater can run on propane with 12 volts for ignition and thermostatic control OR it can run from 120 volts, using a second thermostat OR you can use both at the same time for faster recovery.