DC to DC charger - Fiberglass RV
Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 04-09-2024, 11:24 AM   #1
Junior Member
 
Name: Shannon
Trailer: Casita
Idaho
Posts: 3
DC to DC charger

I'm getting ready to install a Renogy 20 amp DC to DC charger in my Casita (1 12v battery).
I understand the process, new bigger wires from tow vehicle, battery, fuse, connector for trailer new bigger wires to DCDC charger, then to trailer battery, fuse. What about the original charging line from the original 7 pin trailer harness, connected to 7 pin connector on tow vehicle and it's charging system.

That charging line must go to the trailer's electrical "brain," which allows it to charge the battery from tow vehicle, or from 120 volt shore power, for that matter. Also, the other lines in trailer harness allow for turn/brake, running lights, electric brakes...

So I'm unclear as to what to do with that original charging line after DCDC charger install...Help?
spmay is offline   Reply With Quote
Old 04-09-2024, 02:19 PM   #2
Senior Member
 
CharlesinGA's Avatar
 
Name: Charles
Trailer: Bigfoot
Georgia
Posts: 395
If you wish to disconnect it, find the end of the umbilical where it goes into a junction box and disconnect (and tape it up) there.

Just be aware that if the trailer is towed with any other vehicle, it will not have any power into it.

I suspect that many people leave it connected and never have any issues.

Charles
__________________
'03 Ram 2500 CTD, 5.9HO PacBrake six speed std cab long bed Leer top and 2008 Bigfoot 25B21RB.. Previously, 2008 Thor Freedom Spirit 180, SOLD! 2007 Winnebago View 23H Motorhome, SOLD!
CharlesinGA is offline   Reply With Quote
Old 04-09-2024, 04:47 PM   #3
Junior Member
 
Name: Shannon
Trailer: Casita
Idaho
Posts: 3
DC to DC

Thanks. I don't necessarily want to disconnect it. I just don't want to leave it intact and have it screw up the works.
spmay is offline   Reply With Quote
Old 04-09-2024, 06:22 PM   #4
Junior Member
 
Name: Kenny
Trailer: Bigfoot
Georgia
Posts: 17
I'm debating on replacing my battery to lithium for the trailer. I thought about pulling the fuse for the charge line from the truck as an option. I'm going to doublecheck if it's an issue for my truck, but perhaps that could be an option? Not sure if anyone has done that. I'd make sure the battery is fully charged and won't have any 12v loads other than propane detector.
ken_c is offline   Reply With Quote
Old 04-09-2024, 06:31 PM   #5
Senior Member
 
Raspy's Avatar
 
Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,903
spray,

I don't think it is critical to disconnect it, but probably better if you do. The dc-dc charger will be programmed differently than the tow vehicle's charger and there may be times when power is going into the tow from the dc-dc charger.

If you are worried about charging the trailer from another tow, disconnect the 12 volt wire in the tow, instead of in the trailer junction box. This way, the dc-dc charger would not be connected with another two, but the pigtail 12 volt would be.

When setting up the new charging wire to the dc-dc charger, use an Anderson plug at the rear bumper. Then plug in the seven pin and the Anderson wire at each hookup. But remember to disconnect the Anderson if staying for a while so you don't run down the tow's battery. Also, if you use a Victron dc-dc charger, it will be voltage sensing and will not need a signal wire to turn it on. It notices a voltage increase and turns on when the tow is started. Very convenient.
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
Raspy is offline   Reply With Quote
Old 04-17-2024, 11:14 AM   #6
Junior Member
 
Name: Michael
Trailer: Casita
New Hampshire
Posts: 2
Quote:
Originally Posted by Raspy View Post
disconnect the 12 volt wire in the tow, instead of in the trailer junction box
The least destructive way might be to just pull the fuse on the 12v tow circuit on your TV -- easy, non-destructive way to test and easy to restore if you run into trailer "brain" troubles or tow a different trailer or something?
lmgray is offline   Reply With Quote
Old 04-17-2024, 02:33 PM   #7
Junior Member
 
Name: Mike
Trailer: Trillium
Ontario
Posts: 1
Don't use just use the power line in the 7-pin?

I'm confused. Why are you thinking of disconnecting the original wire instead of upgrading it? Would you not upgrade the wire in the 7-pin and use it to feed the power to the DC/DC which then charges your system and powers the trailer? You'll upgrade the wire gauges to allow for more current with less voltage drop but otherwise the circuit is the same but with the addition of the DC/DC connecting inline boosting the voltage up to charge levels. Is that not the normal operation?
MMIndustries is offline   Reply With Quote
Old 04-17-2024, 04:00 PM   #8
Senior Member
 
Raspy's Avatar
 
Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,903
Quote:
Originally Posted by MMIndustries View Post
I'm confused. Why are you thinking of disconnecting the original wire instead of upgrading it? Would you not upgrade the wire in the 7-pin and use it to feed the power to the DC/DC which then charges your system and powers the trailer? You'll upgrade the wire gauges to allow for more current with less voltage drop but otherwise the circuit is the same but with the addition of the DC/DC connecting inline boosting the voltage up to charge levels. Is that not the normal operation?
I don't know how we can generalize how to upgrade the seven pin hot wire by simply saying upsize the wire. Where does it come from on different vehicles? How is it controlled? How much power can the system handle?

A 30 amp dc-dc controller is not a huge size. But even that requires a #6 or larger wire because it requires a 60 amp circuit breaker. Installing a #6 wire with the needed 60 amp breaker, into the small seven pin wire system, seems like a waste of time since we don't know how much power the OEM circuit is designed to carry. But it seems perfectly sensible to predict that none of them are designed for 60 amps.

So, an independent wire, directly from the battery, with its own circuit breaker, bypasses, that design consideration on each brand of vehicle and eliminates any problems of overloading the seven pin system. The wire can terminate at an Anderson plug on the rear bumper, where a dedicated trailer wire can plug in and go directly to the dc-dc charger.
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
Raspy is offline   Reply With Quote
Old 04-17-2024, 08:24 PM   #9
Junior Member
 
Name: Shannon
Trailer: Casita
Idaho
Posts: 3
DC to DC

Good input. Indeed I intend to run the bigger wires from alternator (fused) on TV to anderson plug at back of truck; and bigger wires anderson plug connected from there directly to the DC to DC charger input in the trailer with bigger output wires (also fused) to the house battery.

The 7pin wires, (one of which is the original charging source of trailer battery while driving) are much smaller than the new charge wires to DCDC charger will be. While driving that charging/aux wire from TV to trailer harness delivers the charging from tow vehicle to the in trailer Converter/Charger (Parallax brand), which allows the battery to serve as house power when not plugged in to 120 volt and allows/converts shore 120 volt power to 12 volts and charges the house battery when plugged in.

I've emailed Parallax to see what they recommend since their device is part of the equation. Meanwhile, I'm waiting for Renogy to provide guidance as well. I just don't want to create problems with the DC to DC installation.
spmay is offline   Reply With Quote
Old 04-17-2024, 09:18 PM   #10
Senior Member
 
Raspy's Avatar
 
Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,903
Quote:
Originally Posted by spmay View Post
Good input. Indeed I intend to run the bigger wires from alternator (fused) on TV to anderson plug at back of truck; and bigger wires anderson plug connected from there directly to the DC to DC charger input in the trailer with bigger output wires (also fused) to the house battery.
This is exactly what I did and it worked very well. I don't know about Renogy, but Victron is triggered by the voltage surge when the tow is started. Thus, no switching wire needed. Also, they are bluetooth, so you can set all the parameters and monitor the charging with your phone. Also, I connected my wire to the battery, not the alternator. A short wire went to the firewall where the marine circuit breaker/disconnect switch was mounted. Then on to the rear bumper where the Anderson is mounted. I ran both plus and minus wires in #4 marine Romex.
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
Raspy is offline   Reply With Quote
Old 04-18-2024, 12:03 AM   #11
Member
 
Name: Derek
Trailer: Bigfoot 25RQ
Washington
Posts: 96
I installed a Victron Orion 12/12-18 using the existing 7 pin wiring on my F150 with the factory 30 amp circuit. Since the charging wire is small and the distance is long, the 14.2 volts from my truck alternator drops to around 10.5 volts by the time it reaches the Orion. The Orion then transforms the voltage up to 14.5 volts to charge the lithium trailer battery. To get an output of 18 amps at 14.5 volts requires that the truck charging wire provide an input of 25 amps at 10.5 volts (actually slightly more amps than this due to inefficiencies). But, not more than 30 amps. So, I don't need to run any new wiring. It is my understanding that this is the purpose of the 18 amp charger--it will function with the factory wiring. I am able to monitor the Orion charger while towing using the Victron Connect app and bluetooth and I can see everything in real time--input voltage, output voltage, amps--and I can verify that it works as described above. The only challenge was getting the settings just right. (The trick for me was setting the lockout voltages very low, around 9.5 volts. Otherwise, the charger would cycle off and on.)

If you want more amps than this, you can buy the Victron 30 amp DC-DC charger but you then have to run heavier gauge wire, use Anderson plugs, etc. like has been mentioned. I already have 400 W of solar panels on the roof, so I just wanted enough extra amps to help out on cloudy days to guarantee the battery would be topped off by the end of our drive.

Check out the AM Solar website for more info and schematics.

Derek
Derek Johnson is offline   Reply With Quote
Old 04-18-2024, 10:41 AM   #12
Senior Member
 
Raspy's Avatar
 
Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,903
Great post Derek. Thanks.
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
Raspy is offline   Reply With Quote
Old 04-18-2024, 11:37 AM   #13
Member
 
Name: Troy
Trailer: Casita
Texas
Posts: 52
Quote:
Originally Posted by Derek Johnson View Post
I installed a Victron Orion 12/12-18 using the existing 7 pin wiring on my F150 with the factory 30 amp circuit. Since the charging wire is small and the distance is long, the 14.2 volts from my truck alternator drops to around 10.5 volts by the time it reaches the Orion. The Orion then transforms the voltage up to 14.5 volts to charge the lithium trailer battery. To get an output of 18 amps at 14.5 volts requires that the truck charging wire provide an input of 25 amps at 10.5 volts (actually slightly more amps than this due to inefficiencies). But, not more than 30 amps. So, I don't need to run any new wiring. It is my understanding that this is the purpose of the 18 amp charger--it will function with the factory wiring. I am able to monitor the Orion charger while towing using the Victron Connect app and bluetooth and I can see everything in real time--input voltage, output voltage, amps--and I can verify that it works as described above. The only challenge was getting the settings just right. (The trick for me was setting the lockout voltages very low, around 9.5 volts. Otherwise, the charger would cycle off and on.)

If you want more amps than this, you can buy the Victron 30 amp DC-DC charger but you then have to run heavier gauge wire, use Anderson plugs, etc. like has been mentioned. I already have 400 W of solar panels on the roof, so I just wanted enough extra amps to help out on cloudy days to guarantee the battery would be topped off by the end of our drive.

Check out the AM Solar website for more info and schematics.

Derek
Would love some more info on your set up. What year F150? Did you mount the DC charger on the F150, or in the camper? Can you adjust the output? I
justa25thTA is offline   Reply With Quote
Old 04-18-2024, 12:02 PM   #14
Member
 
Name: Derek
Trailer: Bigfoot 25RQ
Washington
Posts: 96
My truck is a 2005. The charger is mounted in the trailer near the electrical panel. I just disconnected the 7-pin charging wire from the factory panel and ran it to the DC charger instead, then ran the output to the battery (actually to the Victron Lynx Power in--this component really simplified my layout--highly recommended if you are installing solar and inverter as well).

The output is not adjustable, but I don't know why you would need that. If your battery is low it puts out the full 18-20 amps, then the amps drop as the voltage of the battery increases and approaches 14.5 v. The charger then drops from bulk charging to absorption, and finally to float. What you can adjust is the charging voltage, the float voltage, and the absorption time among a few other things. Download the Victron Connect app, go to the demo library, and select the charger. You will be able to see all of your setting options. (Note that on an installed unit the truck must be running for the DC charger to show up in Victron Connect so you can adjust the settings.)

Also--Victron is just coming out with a new DC charger that some folks are excited about, but I believe it is 50 A and would require new wiring.

If you look back in the electrical forum you can find my earlier post showing pictures of the install, and then later another post about how it functioned on our trip.

Derek
Derek Johnson is offline   Reply With Quote
Old 04-28-2024, 08:35 PM   #15
Senior Member
 
Name: zack
Trailer: scamp 13
California
Posts: 350
Great thread. Thanks everybody. Good info!
zack sc is offline   Reply With Quote
Old 05-07-2024, 11:11 AM   #16
Junior Member
 
Name: chris
Trailer: Casita
New Mexico
Posts: 5
I'm planning on adding a dedicated Anderson SB50 connector on our tow vehicle and using that to connect to our 2021 Casita. I'm debating not having a SB50 connector on the trailer and just having a fixed cable with a SB50 on the end that will plug into the tow vehicle, much like how the 7-pin is fixed on the casita side. Mostly because I'm having problems figuring out a good mounting point for a SB50 panel mount.

Anyone have any great ideas for that?
christsay is offline   Reply With Quote
Old 05-07-2024, 02:37 PM   #17
Senior Member
 
Raspy's Avatar
 
Name: John
Trailer: Roamer 1
Smith Valley, Nevada
Posts: 2,903
Quote:
Originally Posted by christsay View Post
I'm planning on adding a dedicated Anderson SB50 connector on our tow vehicle and using that to connect to our 2021 Casita. I'm debating not having a SB50 connector on the trailer and just having a fixed cable with a SB50 on the end that will plug into the tow vehicle, much like how the 7-pin is fixed on the casita side. Mostly because I'm having problems figuring out a good mounting point for a SB50 panel mount.

Anyone have any great ideas for that?
I've done it on two of my trucks.

Mount an Anderson plug to the rear bumper of your truck. They come with mounting holes in the plugs. Then make a new pigtail for the trailer side that runs from the dc-dc charger to the tongue. Plug this second pigtail into the truck side Anderson plug when you connect your seven pin. You'll just have two pigtails to plug in. Use rubber jacketed, fine stranded wire for the trailer side pigtail so it can flex as needed.

A good wire for the truck side is marine grade Romex, stranded and tinned wire, two conductors, in a PVC jacket. Connect it to the tow vehicle's battery terminals with a marine circuit breaker on the plus side.. The wire size and breaker rating will be determined by the amperage of the dc-dc charger. The 30 amp Victron asked for a 60 amp breaker. They also make an 18 amp model.

Victron is a good brand of charger because it need no signal wire to turn it on. It senses a voltage increase in the wire when the tow is started and that triggers it to start charging, and shut off when the engine is shut off. All parameters are adjustable, through bluetooth, on your phone. Simple easy and you can monitor it with your phone.
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
Raspy is offline   Reply With Quote
Old 05-07-2024, 03:09 PM   #18
Junior Member
 
Name: chris
Trailer: Casita
New Mexico
Posts: 5
Quote:
Originally Posted by Raspy View Post
I've done it on two of my trucks.

Mount an Anderson plug to the rear bumper of your truck. They come with mounting holes in the plugs. Then make a new pigtail for the trailer side that runs from the dc-dc charger to the tongue. Plug this second pigtail into the truck side Anderson plug when you connect your seven pin. You'll just have two pigtails to plug in. Use rubber jacketed, fine stranded wire for the trailer side pigtail so it can flex as needed.

A good wire for the truck side is marine grade Romex, stranded and tinned wire, two conductors, in a PVC jacket. Connect it to the tow vehicle's battery terminals with a marine circuit breaker on the plus side.. The wire size and breaker rating will be determined by the amperage of the dc-dc charger. The 30 amp Victron asked for a 60 amp breaker. They also make an 18 amp model.

Victron is a good brand of charger because it need no signal wire to turn it on. It senses a voltage increase in the wire when the tow is started and that triggers it to start charging, and shut off when the engine is shut off. All parameters are adjustable, through bluetooth, on your phone. Simple easy and you can monitor it with your phone.
Awesome yep that's the plan.

I'm frequently ~700 miles from the trailer and the truck so I'm going to stage this out:

Stage 1:
Victron Orion XS and SmartShunt install
Connect the +12V from the 7 pin to the Victron and turn down the input amps. Truck wire is fused at 40A so I gotta check to see what's in the Casita, I expect a 10AWG

Stage 2:
Anderson SB50 wiring on the truck
50A AMI fuse and 75A weather proof relay switched by ignition in the engine bay
6AWG from engine to the bumper terminated in a SB50
6AWG pigtail from Orion XS to SB50

Crank up the amps!

while I'm in there: Better battery terminals on the truck to hang all these accessory power taps from...

Stage 3:
LiFePO4 in a group 31 size
Progressive Dynamics 4655VL converter upgrade
christsay is offline   Reply With Quote
Old 05-08-2024, 12:41 PM   #19
Junior Member
 
Name: Lurk
Trailer: Shopping
Colorado
Posts: 8
Quote:
Originally Posted by MMIndustries View Post
I'm confused. Why are you thinking of disconnecting the original wire instead of upgrading it? Would you not upgrade the wire in the 7-pin and use it to feed the power to the DC/DC which then charges your system and powers the trailer? You'll upgrade the wire gauges to allow for more current with less voltage drop but otherwise the circuit is the same but with the addition of the DC/DC connecting inline boosting the voltage up to charge levels. Is that not the normal operation?
I agree with you MMI - I'm a bit confused by this thread too, but could be I missed something. Almost seems two topics are being mixed- primary wire size upgrade and DC DC charger.

Personally, upgrading the tow vehicle cabling would not be high on my project list - the Casita has a small battery and the benefits just don't scale enough to justify the effort. Reducing charging time by 205-40% on a 1000AH battery bank could mean several hours. On a 100AH battery bank typically found in a Casita? Reduction would be measured in minutes.

But adding a DC-DC charger is recommended if the FLA/AGM house battery is swapped for LFP. If you also have solar, a handy device is the 50A dual-input DC-DC charger from Renogy. Hook-up your solar, hook-up your alternatory, and you're done. Caveat -I'm not a fan of Renogy's due to lousy customer service and lame monitoring (you have to purchase a separate dongle). But their 50A DC-DC (HERE) with MPPT is handy and I've installed it on a camper van.

One item I have not seen mentioned is charging a LFP from the onboard 120VAC charger when plugged in to shore power. Guessing only trailers produced in last couple years are LFP compaptible.

Note that Victron and Renogy DC-DC chargers both act as a blocking diode to prevent accidental discharge of the battery on the tow vehicle. If you still have a solenoid in your alternator circuit, it can be removed though there isn't much harm in keeping it.
CoMan is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
How can you make a dumb converter/charger a smart charger? Timber Wolf Electrical | Charging, Systems, Solar and Generators 10 03-09-2016 12:11 PM
Solar Powered Battery Charger Rich S Electrical | Charging, Systems, Solar and Generators 6 10-17-2006 09:19 AM
Battery Charger Needed Patrick M. Electrical | Charging, Systems, Solar and Generators 30 07-24-2006 07:00 AM
Solar charger questions Steve Rosenberg Care and Feeding of Molded Fiberglass Trailers 17 12-01-2005 02:00 AM
Converter/charger Legacy Posts Care and Feeding of Molded Fiberglass Trailers 31 02-02-2003 08:47 PM

» Upcoming Events
No events scheduled in
the next 465 days.
» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 10:04 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.