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Old 01-22-2021, 12:27 AM   #1
2 Rivet Member
2016 19' Flying Cloud
Los Altos , California
Join Date: May 2020
Posts: 89
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question on installing small dc to dc isolating charger

I'm going to install small VIctron 9amp dc to dc charger in my 19ft flying cloud to stop power flowing back to the TV. I have a question on wiring it. I'm installing it inline in the trailer near the front where the band of wires from the hitch cord come through the floor and connect to the bus bar and the tail-light distribution box.

There is a black wire that goes to the bus bar. That is the charge or power wire and there is a white wire going to the ground of the bus bar. Do I just take both of those and connect them to the input terminals of the dc to dc charger and then wire up the output terminals to the the same locations as original black and white wires?

disconnecting the white grnd wire appears to disable the running lights and brakes. Should I just leave that as is and run a new ground from charger to bus bar?
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Old 01-22-2021, 06:16 AM   #2
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2018 25' International
Slidell , Louisiana
Join Date: Sep 2017
Posts: 3,477
As you have discovered, the white is the common vehicle battery negative used for all vehicle to trailer functions (lights, brakes, charging, auxiliary).

It can be wired either way but since the white is a common wire it may be slightly better to wire it the second way with both negatives of the DC charger attached to the negative/gnd bus.
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Old 01-22-2021, 07:56 AM   #3
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2004 28' Classic
Monument , Colorado
Join Date: Nov 2015
Posts: 945
I agree with BayouBiker and the OP. On my Renogy 20 amp DC/DC charger, I ran new 4AWG wires from the TV battery to Anderson power pole connectors into the charger inputs in the trailer. I disconnected the black wire from the 7-way harness to the positive bus bar to prevent the lithium batteries from draining the TV battery and left the common connected.
2004 Airstream Classic 28 "Willard"
2014 Ford F150 FX4 Ecoboost
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Old 01-22-2021, 10:55 AM   #4
2 Rivet Member
2016 19' Flying Cloud
Los Altos , California
Join Date: May 2020
Posts: 89
Images: 2
thanks! I'm not going to do any mods to the Jeep TV. I have solar and a gen. so just looking for a little boost of charge while driving (only getting about 4amps now) and stop TV from drawing power from Trailer lithium batts.. It's about 3-4amps of draw when engine is stopped..

I will leave existing white neutral connected as is to bus bar and run two new negative wires to bus bar from DC-DC converter. .

My hope is that I will get around 9amps of charge while engine is on with the new device.
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Old 01-22-2021, 11:32 AM   #5
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2017 27' International
Wasilla , Alaska
Join Date: Feb 2018
Posts: 268

recently ordered a Victron DC-DC 20 amp and will be locating and connecting it under the front twin on the curb side. New LiFePo batteries will be in the front storage compartment strapped and padded appropriately. Still colder outside than I care to fool with so will be following your experience so I am informed when the snow melts!
2017 Int'l Serenity 27FB
2020 F250 powered by converted solar
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