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Travel Trailer wiring to WFCO Power Center with LiFePO4 upgrade

photodavo

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Joined
Aug 15, 2024
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3
Location
Golden, CO
I am in the process of upgrading the battery in my 2010 T@DA travel trailer to a LiFePO4 100AH battery and adding a new MPPT solar charge controller to connect a couple of portable 200W PV panels that I already have. My question is about the wiring to the existing WFCO 8955 Power Center that provides AC and DC distribution as well as AC to DC converter from shore power and 12V battery charging. In the current setup the positive battery wire connects to the DC side of the WFCO unit and the negative battery wire is connected to the frame of the trailer. The negative wire on the WFCO unit is connected to an existing bus bar and then another wire of similar size is connected from that bus bar to the frame of the trailer. This bus bar also has all of the smaller negative wires for the DC loads connected to it.

As part of my LiFePO4 battery upgrade I am also relocating the battery to an interior cabinet. The new battery positive wiring will run to a battery disconnect switch and then a new positive bus bar. The positive wire from the WFCO unit will connect to this bus bar along with the solar charge controller. This seems pretty straight forward. Where it gets confusing for me is the negative wiring. I plan to connect the negative battery wire to a new negative bus bar and then run a new wire from the negative bus bar to the trailer frame. Do I then need to connect the negative wire from the WFCO unit to my new negative bus bar or can it stay wired to the camper's existing negative bus bar since both are wired to the trailer frame? I would like to keep all of the DC load connections to the camper's negative bus bar alone if possible. What is the proper way to run the wiring from the new battery to the existing WFCO power center to power the DC loads in the camper?

On a side note, since the WFCO's converter/charger does not support LiFePO4 charging profiles/voltage I plan to simply turn off the battery disconnect switch for the rare occasions that we are connected to shore power and disconnect the 12V aux power wire from the 7 PIN connection from my tow vehicle to eliminate the possibility of damaging the new battery or tow vehicle. We usually have no trouble keeping the battery charged with just the solar charging and typically camp in areas that do not provide electrical service anyway. I also have an AC charger for the LiFePO4 battery that I can plug in to an AC outlet for charging the battery in the rare event that we are connected to shore power but this would again be rare. I also plan to run a wire directly from the battery to the trailer breakaway switch.

I am pretty new to a lot of this but trying to learn and this form has been very helpful in that regard. Thanks in advance for any help with my questions!

Current Wiring

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New Wiring...or not

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If you don't currently have a shunt-based battery meter, you will want to install one if your battery does not come with a Bluetooth app. Also, a diode installed between the junction box and the batt+ will eliminate the need to unplug the 7-pin when you are parked. Finally, if your 12v system works with the chargeverter powered off, you can just use its breaker to manually switch the chargeverter on and off. I did a similar conversion last fall, and decided to buy a stand alone LifePo4 40 amp charger (about $160) that I use to charge my 230 Ah battery when connected to shore power.
 
I agree with turning off the circuit breaker to disable the converter.

It's good to see you are considering the trailer breakaway system.

In most trailers, the 7 pin cable terminates in a box under the trailer near the front of the trailer. You can disconnect the battery charge wire of the 7 pin cable there and none of the tow vehicle power will make it into the trailer.
 
Thanks for the responses! I will disconnect the battery charge wire from the 7 PIN and also see if turning off the circuit breaker for the converter charger does what I need for the shore power scenario.

I am still trying to work out the negative wiring for the new battery and WFCO power center.

Summary of original camper wiring:
- Original Battery positive connected to WFCO 12V DC positive
- Original Battery negative connected to trailer frame
- WFCO negative 12V DC connected to camper bus bar
- Camper bus bar connected to trailer frame (along with all DC load negative wires)

1724073555675.png

Proposed wiring with new LiFePO4 battery and bus bars
- LiFePO4 Battery positive connected to disconnect switch and then new positive bus bar
- WFCO positive connected to new positive bus bar
- LiFePO4 Battery negative connected to new negative bus bar
- Negative bus bar connected to trailer frame
- WFCO negative remains connected to trailer bus bar which is also connected to trailer frame
- Solar Charge Controller also connected to positive and negative bus bars

1724073657658.png

The 12V loads and solar charging work using the above wiring design but I am not sure if this is the correct way to wire the negative side.

Any suggestions?

Thanks!
 
As long as that red wire from the battery to the junction box is providing power ONLY to the breakaway system, that's good.
 
Yes, I planned to connect that wire from the battery positive directly to the breakaway switch and nothing else. Thanks!
 

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