DC to DC Charging
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2nd Gear
Joined: Jun 2023
Posts: 2
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DC to DC Charging
Hey guys. Who of you has added a DC to DC Charger in their Super Duty with a 2 Battery Set up / 397 amp alternator? Can you please give me some tips / pointers as to how you wired it? Which battery did you use? Where / how did you place your inline fuse? How did you route the wire ect? Thanks in advance!
Mountain Pass
Joined: Mar 2010
Posts: 183
Likes: 27
From: Northern CA
I recently bought a popup truck camper and the dealer did the DC to DC charger wired to my 21 F350 with dual batteries. I'm certainly not an expert but I do have a couple of things that I am pretty sure are accurate to share.
One is the wire from the battery should be fused as close to the battery as possible, mine is on the firewall but about the shortest distance they could get. Also as important is their should also be another fuse at the camper battery for this same wire.
Make sure the wire you use is big enough for the amps and distance and maybe a little bit larger. Many folks are saying that for 30amps 8 or 6ga. wire is needed for both the hot and gournd.
The dealer used my driverside battery but the passenger side has some extra posts that are easy to use. I had already used my passenger side for something else.
You might also search for another forum dealing with overlanding the west that has good information on pick up truck camping and DC to DC chargers.
Good luck.
One is the wire from the battery should be fused as close to the battery as possible, mine is on the firewall but about the shortest distance they could get. Also as important is their should also be another fuse at the camper battery for this same wire.
Make sure the wire you use is big enough for the amps and distance and maybe a little bit larger. Many folks are saying that for 30amps 8 or 6ga. wire is needed for both the hot and gournd.
The dealer used my driverside battery but the passenger side has some extra posts that are easy to use. I had already used my passenger side for something else.
You might also search for another forum dealing with overlanding the west that has good information on pick up truck camping and DC to DC chargers.
Good luck.
Cross-Country
Joined: Oct 2018
Posts: 56
Likes: 54
From: MI
I recently posted the following in the IRV2.com forum. Lots of info there.
I have a Renogy 40A DC to DC charger mounted in my rig, a couple of feet from my batteries. I "feed" the charger through a 2awg umbilical that connects (via 175A Anderson type connectors) to the truck at the hitch. The truck connector has 2awg wire that grounds at the rear of the truck frame. The 2awg positive runs along the truck frame through flexible conduit and is connected to a 200A continuous rated Cole Hersee relay mounted near the firewall. The other side of the relay is connected to the passenger side battery via a 60A terminal fuse. Mr Fluke tells me there is no voltage loss at the back of the truck.
The relay is triggered by upfitter switch #1. So I can control the Cole Hersee relay from the driver seat. And the system cannot be "hot" when the truck is not "on."
Apparently fuses work better under the hood than circuit breakers. The terminal fuse block is smaller and easier to mount than the ANL fuse holder that I initially tried. I originally put a cheap 50A circuit breaker between the charger and battery bank (the output side). I have since replaced it with a 50A ANL fuse. A quality (Blue Sea?) circuit breaker would probably work, but they aren't cheap - stay away from the cheap ones. The charger's output cables are a short (<3') 8awg.
I have a Renogy 40A DC to DC charger mounted in my rig, a couple of feet from my batteries. I "feed" the charger through a 2awg umbilical that connects (via 175A Anderson type connectors) to the truck at the hitch. The truck connector has 2awg wire that grounds at the rear of the truck frame. The 2awg positive runs along the truck frame through flexible conduit and is connected to a 200A continuous rated Cole Hersee relay mounted near the firewall. The other side of the relay is connected to the passenger side battery via a 60A terminal fuse. Mr Fluke tells me there is no voltage loss at the back of the truck.
The relay is triggered by upfitter switch #1. So I can control the Cole Hersee relay from the driver seat. And the system cannot be "hot" when the truck is not "on."
Apparently fuses work better under the hood than circuit breakers. The terminal fuse block is smaller and easier to mount than the ANL fuse holder that I initially tried. I originally put a cheap 50A circuit breaker between the charger and battery bank (the output side). I have since replaced it with a 50A ANL fuse. A quality (Blue Sea?) circuit breaker would probably work, but they aren't cheap - stay away from the cheap ones. The charger's output cables are a short (<3') 8awg.
Hotshot
Joined: Oct 2015
Posts: 19,719
Likes: 12,861
From: Wyoming
I've been told that fuses have less resistance than circuit breakers. At higher amperages, DC circuit breakers get expensive! When I do put in a breaker, I use either Blue Sea Systems or Midnite Solar.
4wd Low
Joined: Apr 2022
Posts: 12
Likes: 7
I have the dual alternator (397A) and dual batteries. I connected to the driver's side battery because it was closer to where I was going to run the cable. I installed the fuse on top of the driver's side battery and ran 2 gauge cable to an Anderson connector the rear bumper. I used two gauge because for the length it can easily handle more than 60A. The wire is run along the frame on the left side of the truck. From the rear bumper, I use a short pigtail to another Anderson connector on the camper. Inside the camper, the wires run to a terminal block near all my electronics (forward end of the basement). I then ran separate 10 gauge wire to two DC/DC converters which are in turn each connected to the house side terminal blocks (load, battery, inverter, MPPT, etc).
Mountain Pass
Joined: Jul 2012
Posts: 132
Likes: 37
I installed a renogy 50 amp dc to dc charger with mppt. Connected to driver side battery, inline 60 amp fuse. I used 6 awg welding cable ran it through expandable braided cable sleeve. Followed the factory harness down the frame rail entered the bed via the inspection plug on the front of the bed. Used a 90 degree liquid tight connector and 1/2 hose to protect the cables from abrasion. I have dual alternators and used the brown ignition on wire from upfitter bundle to trigger the dc to dc charger. I have another 60 amp fuse coming off the hot side on the dc to dc charger before the bus bar. The dual 100 ah lithium batteries are wired in series with a disconnect switch to prevent powering my truck topper.
Hotshot
Joined: Oct 2015
Posts: 19,719
Likes: 12,861
From: Wyoming
I installed a renogy 50 amp dc to dc charger with mppt. Connected to driver side battery, inline 60 amp fuse. I used 6 awg welding cable ran it through expandable braided cable sleeve. Followed the factory harness down the frame rail entered the bed via the inspection plug on the front of the bed. Used a 90 degree liquid tight connector and 1/2 hose to protect the cables from abrasion. I have dual alternators and used the brown ignition on wire from upfitter bundle to trigger the dc to dc charger. I have another 60 amp fuse coming off the hot side on the dc to dc charger before the bus bar. The dual 100 ah lithium batteries are wired in series with a disconnect switch to prevent powering my truck topper.
I tend to use pessimistic numbers to be on the safe side. Your alternator is going to put out a voltage higher than 13.0 volts.
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Mountain Pass
Joined: Feb 2017
Posts: 201
Likes: 9
From: Vancouver Island
I wouldn't be surprised if the 60 amp fuse on the truck side of the DC-DC charger blows. The charger puts out 50 amps (max) but to that it will draw more than 50 amps, upwards of 60 amps, probably more. A 60 amp draw over 30' length of cable (round trip) at 13 volts will have a 5.6% voltage drop. To account for the voltage drop, the amps will have to come up. This is a worst case scenario which requires the LiFePO4 batteries to be at a certain state of charge (say less than 70%) such that the DC-DC charger decides to do a bulk charge at full throttle. If your round trip wire distance is less than 30' the voltage drop gets better.
I tend to use pessimistic numbers to be on the safe side. Your alternator is going to put out a voltage higher than 13.0 volts.
I tend to use pessimistic numbers to be on the safe side. Your alternator is going to put out a voltage higher than 13.0 volts.
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Mountain Pass
Joined: Jul 2012
Posts: 132
Likes: 37
I wouldn't be surprised if the 60 amp fuse on the truck side of the DC-DC charger blows. The charger puts out 50 amps (max) but to that it will draw more than 50 amps, upwards of 60 amps, probably more. A 60 amp draw over 30' length of cable (round trip) at 13 volts will have a 5.6% voltage drop. To account for the voltage drop, the amps will have to come up. This is a worst case scenario which requires the LiFePO4 batteries to be at a certain state of charge (say less than 70%) such that the DC-DC charger decides to do a bulk charge at full throttle. If your round trip wire distance is less than 30' the voltage drop gets better.
I tend to use pessimistic numbers to be on the safe side. Your alternator is going to put out a voltage higher than 13.0 volts.
I tend to use pessimistic numbers to be on the safe side. Your alternator is going to put out a voltage higher than 13.0 volts.
5th Wheeling
Joined: Sep 2009
Posts: 25
Likes: 3
This is a good YouTube walk through on how he did his system and how the dual alt system on the '19 SD performed.
http://No Generator RV Alternator Ch...h Explore More
http://No Generator RV Alternator Ch...h Explore More
4wd Low
Joined: Nov 2014
Posts: 11
Likes: 0
From: On the road
Some good info here. I have a 2017 6.7 Lariat with plow package and dual HD alternators (don’t know their exact size- apparently another thread I found indicates this is up for debate.) Anyway, I fathom putting a 30 Amp Victron DC/DC isn’t going to be a stretch for the truck.
What’s the difference between the driver’s and passenger side battery hookup, other than location on the truck? I don’t want to cause an overload situation- I do plan to setup the system such that the charger is only pulling a load when the alternator is clearly above idle output.
Thanks!
What’s the difference between the driver’s and passenger side battery hookup, other than location on the truck? I don’t want to cause an overload situation- I do plan to setup the system such that the charger is only pulling a load when the alternator is clearly above idle output.
Thanks!
Hotshot
Joined: Oct 2015
Posts: 19,719
Likes: 12,861
From: Wyoming
The dual batteries are wired in parallel, so there's not much difference in connecting one or the other. There have been a number of posts suggesting that you should use the battery that is wired the closest (in wire length) to the alternator.
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