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aiellost avatar image
aiellost asked

Isolated or non-isolated Orion charger question for my 5th wheel

Recycled Question: Which B2B charger for trailer in the US. Isolated vs. Non Isolated?

1) Tow vehicle and trailer are bonded through wiring harness 7 pin connector to facilitate running lights on trailer. # 14awg. (this conductor is grounded on both trailer and tow vehicle frames)

2) 7 pin connector harness also has a #14 wire for (+) 12vdc to trickle charge trailer batteries when tow vehicle is running.

3) Trailer LifePo4 batteries are grounded to trailer frame (as is the #14 from tow vehicle, as previously stated)

We know the #14 wires are not suitable for 30a charging therefore:

1) do we disconnect the 12vdc (+) in the wire harness?

2) do we disconnect the 12vdc (-) thus isolating the vehicles ground bond, the running lights will not work as designed, having to depend on the physical hitch connection for a (-) return path to tow vehicle battery.

please advise

best regards

Steve



battery charging
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1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

For 30 amps you need a minimum of #10 AWG wire. Plus for any length, a much larger wire (#6 at least).

Do not disconnect any of the existing wiring, but consider increasing the wire size from the battery to the 7-pin's +12 connection. Then do the same in the trailer from the 7-pin to the DC-DC charger.

Make sure the ground wire in the 7-pin is #10 and keep it's length as short as possible bonding it to the frame at the closest point.

Using the frame as the return connection is probably OK and should be less voltage drop than a separate wire. But do not rely on the hitch to make a reliable connection.

Alternately, you can provide a completely separate connection using larger wire and separate connector (such as Andersen).

You will probably end up with significant voltage drop from the battery to the DC-DC charger and not be able to use the automatic (voltage based) control. You will need to run a separate on/off line somewhere. I used the running light which means the DC-DC charger only works with the vehicle lights on but for me that's OK since I always travel with lights on anyway.

As far as isolated vs non-isolated, it should not matter if the DC-DC charger is located with 2-3 cable feet of the battery.

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