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DC-DC charger wiring

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Bluetick

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I've seen posts about this subject but none address how to run the 4gauge cables from the bed to the battery. I don't want to make any cut-outs in the bed and the only existing one is occupied by a 30A plug. Which is where I'd like my DC DC charger cable to go. Couple questions. What, exactly, does that 30A plug attach to? Is it simply two heavy duty cables that run directly to one of the batteries? If so, why couldn't I cut off the 30A plug and replace it with an Anderson type quick connect that can receive the plug running from my trailer batteries and the DCDC charger? Otherwise, I'm stumped as to a good way to run some new 4gauge wires for the set up. The truck in question is a 2018 Ram 3500 dually.
 
What 30A plug are you referring to? The 7-pin trailer wiring?

You’re likely going to have to make a small hole and use a grommet to protect the wires, like in the firewall.

I haven’t fully planned my install out yet, but I’ll probably have the wires come thru the aft corner in front of the tail light. With the tail light removed it’s easy to pull wires from the frame up to the bed.

You only need to run one wire from the battery to the bed, the negate can come from the frame much closer.
 
The 7-pin plug is externally located just above the rear bumper. The 30A is inside the bed on the driver side about a foot forward of the tailgate.
 
Most of the installations I've seen run the 4 awg wire along the frame to the rear and let the powerpole connector dangle with a zip tie near the hitch. I did see one install where the person drilled a hole in the bumper for a flush mount powerpole connector. I've heard the quality on the Powerwerx flush mounts is mediocre however. There's supposed to be a quality one from Anderson Connect in Australia. Not sure what it would cost to get one here however. I think for a travel trailer most people prefer to keep the connection near the 7 pin, so inside the bed mount examples may be sparse.
 
Bluetick said:
The 7-pin plug is externally located just above the rear bumper. The 30A is inside the bed on the driver side about a foot forward of the tailgate.
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If the in-bed connection you're talking about is the 120 V inverter plug, that wiring isn't going to be heavy enough for a DC-DC connection. The DC wiring to the inverter is heavy gauge, but from inverter to the plug is much lighter as it's AC.
 
Bluetick said:
The 7-pin plug is externally located just above the rear bumper. The 30A is inside the bed on the driver side about a foot forward of the tailgate.
Click to expand...

Is this 30A factory?

Neither my '18 nor '22 have any plugs in the bed that aren't the 5th wheel prep 7 pin (plus 12-pin/120VAC on the '22).

Pics are worth 1000 words, so they say.

tyler2you said:
If the in-bed connection you're talking about is the 120 V inverter plug, that wiring isn't going to be heavy enough for a DC-DC connection. The DC wiring to the inverter is heavy gauge, but from inverter to the plug is much lighter as it's AC.
Click to expand...

I don't believe that was an option on the '18's. IIRC it was first available on the '20's or '21's.
 
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I ran a heavy gauge harness from my battery thru the frame and then came up the stake pocket. On mine there was an opening on the frame directly below the stake pocket and then i ran the harness out the hole for the tie down
 
Bringing back an older thread, hopefully for an update from wiser members. I've go a 22 LB CC HO which I'm looking to install the wiring for dc/dc chargers for my bumper pull trailer. I've got (2) 225 amp alternators so not worried about my possible useage. My question is what size wire would be needed for the following: (1) Victron 12/50 dc/dc charger with the possibility of adding a 2nd Victron 12/50 charger later on, for a total of up to 100 amps? I want to do it right the 1st time and not redo or bandage something together. I want to terminate with and Anderson connector at the rear bumper area, not in the bed. Also what size fuse and what size Anderson connector would be recommended?

The eventual battery capacity will be between 990-1320 AH, depending on 3 or 4 batteries. Hopefully someone has done something similar.

Thanks in advance.
 
For that big of a potential draw you're going to need something between 2/0 and 2 AWG, depending on the amount of voltage drop you're willing to accept. 10% drop you can use 2, 3% you're going to need closer to 2/0. The Victron won't take either of those wire sizes, so you're going to have to terminate at a fuse block to reduce wire size there. The fuses should be rated no higher than the max capacity of your wire.

For the Andersen connector use an SB120 for 2 AWG. An SB175 will fit 2/0, but that’s a big connector.

I might be tempted to wire them with two individual runs of 2 AWG if it were me. Reason being that 2 AWG is way cheaper, and way easier to work with, and it gets you some redundancy.
 
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jsalbre thanks for the response. If I understand you correctly then, for 100 amp capacity, with the voltage drop, my draw from the alternators would be 2AWG 110 amps & 2/0 would be 103 amps, correct? Trying to wrap my feeble brain around this project correctly.
 
Essentially. I wouldn’t expect exactly those numbers, but something close to, depending of course on the exact length of your run (bi-directional, don’t forget), and the actual draw your DCDC is pulling at any given moment.

Just as a heads-up, I installed mine with 2 AWG. When set to detect engine running the Victron XS will reduce its charge as the voltage gets lower until it hits a cutoff point. Voltage drop over the line caused some issue with that for me until I played with the cut-off settings a bit. I’ve been told they’re working on some new firmware to calculate in line drop and correct for that.
 
I did run on my old truck a 'starter-cable' from engine bay into the truck bed.
From there I had anderson plugs and did run another starter-cable into my 5th wheel to the dc 2 dc charger.
Important to check that your alternator has enough power. Especially when you plan on 60amp dc 2 dc chargers.
 
jsalbre; I will probably go with the 2AWG. With twin 225 alternators I feel like it should be able to handle the few extra amps.

Thanks,
Larry
 
RAM_GA Unless I'm way off on my electric needs under normal I expect to be well equipped to handle the extra amps. M reasoning is that my HO Cummins came with just one alternator, with the option of a 2nd one when ordered. I wanted to make sure I had enough for whatever I threw at it in the future. I wish I would have ordered the aux switches, but I didn't know better at the time. Live and learn.

Thanks,
Larry
 
Rampingup said:
jsalbre; I will probably go with the 2AWG. With twin 225 alternators I feel like it should be able to handle the few extra amps.

Thanks,
Larry
Click to expand...

Not that big of a deal, but the OEM alternators are 220A.
 
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