DC to DC charger wiring - 2022 T@b 320 Boondock

VonAustria

My camper is a new-to-me adventure and trying to figure it all out and this forum is such a great tool to use. It’s fantastic. Currently planning to wire my 40 watt dc to dc battery charger to my tow vehicle battery/alternator. I want to run a pair of 4 gage wires into my 2022 t@b 320S BD and I do not have any idea how or where I should run the wiring into my camper. I am installing the charger under the driver’s side seating next to the wheel well area. Any suggestions how or where I should do this?

(Title edited to invite help😊 - Moderator)

pthomas745

Here is a search for "DC Charger".  Sift through and there are some for installing one in a 320.  Some of the others, it seems are asking if one is "required", etc.

https://www.google.com/search?q=dc+charger+site:tab-rv.vanillacommunity.com&client=firefox-b-1-d&sca_esv=588105669&sxsrf=AM9HkKl8z7ALXtSivST1ZtSnr5XkslajeA:1701819301560&ei=pbNvZYrtIZmPur8P_9qd6Aw&ved=0ahUKEwjK08P3uvmCAxWZh-4BHX9tB80Q4dUDCBA&uact=5&oq=dc+charger+site:tab-rv.vanillacommunity.com&gs_lp=Egxnd3Mtd2l6LXNlcnAiK2RjIGNoYXJnZXIgc2l0ZTp0YWItcnYudmFuaWxsYWNvbW11bml0eS5jb21IvyxQvghYwiZwAXgAkAEAmAF3oAHrCaoBBDI1LjG4AQPIAQD4AQHiAwQYASBBiAYB&sclient=gws-wiz-serp

Yoshi_TAB

Hi,

There is no easy way to run wires from outside to inside the TAB 320.  Some have cut holes in the floor in the wheel well areas.  If you remove the protective exterior shield, you can see where the water tanks and other things are.  Then with a few measurements, you can find a place to use a small hole saw.  I did see a post once where someone was able to fish some wires through the penetration where the existing wires come through.  Keep searching with key words and i'm sure it will pop up.  Maybe someone else knows about it.  Here area couple of threads.

Running a wire from battery to inside T@b - Page 2 (vanillacommunity.com)

Running Wires Into T@B? (vanillacommunity.com)

otr_320

We recently ran a large SOOW cable from a gen/shore transfer relay located in the driver's side wheel well area to a generator (*) located on the tongue/A-frame area of our '23 320.  This same run should work well for your proposed run of 4 gauge cable for your dc2dc charger install.  Here's how we ran it:

1) Removed the black, plastic shroud/box located on the exterior, just underneath the shower drain.  For steps 2 and 3 it might help to fish a smaller wire through first, then pull the cable through.  2) From inside, ran the cable down the front side of the wheel well through the opening near the floor leading underneath the shower pan.  3) Pushed (or pulled as the case may be) the cable forward, alongside the shower drain plumbing about 12-18 in. then down through the opening in the floor (previously covered by the black box). 4) Cut a hole in the black, plastic shroud/box to route the cable through.  5) Reinstalled the black plastic box.  6) Secured the remaining cable with cable clamps as it traversed its way along the frame to the tongue/A-frame area. 

This being said, there may be other options to consider.  Lots of collective knowledge here.  No doubt others will chime in with more mounting locations and cable routing options.

We've installed a number of dc2dc chargers in previous RV's and tow vehicles we've owned.  Here's a few tips we learned along the way:

Have you decided on a 12v ignition source to activate the dc2dc charger (D+ terminal on a Renogy)?  Many folks run a wire from the ignition or other switched 12vdc source to the dc2dc charger.  That's a bit of work and still leaves you vulnerable to discharging your tow vehicle battery if you inadvertently leave the ignition (or switch) on without the engine running.  You might consider installing a generic battery isolator next to the dc2dc charger instead.  The battery isolator will only activate the dc2dc charger if the voltage on the dc2dc charger's primary input is greater than 13.3v. The alternator must be online producing current in order for this voltage to rise above 13.3v; otherwise, the dc2dc charger remains off.

Also, most vehicles have battery/alternator to frame/negative connections that are capable supporting the full rated output of the alternator.  This allows use of the vehicle's frame for most of the negative cable run---saving time and money.  Instead of running a negative cable the entire length of the vehicle (battery to rear bumper), simply make a secure negative connection to a primary frame member somewhere near the rear bumper of the vehicle. From there run the negative (and positive) cables the remaining distance to the 320. Recommend using a 175a Anderson connector (or something similar) as a disconnect point between the Tacoma & 320.

Lastly, don't try to scrimp and undersize the cables that run from the tow vehicle battery to the dc2dc charger input.  The dc2dc charger will "work" with undersized cables, but it will significantly increase the load on the alternator.  A 40a dc2dc charger with undersized cables can pull as much as 60a from the alternator to produce 40a of charge current.  The same 40a dc2dc charger with physically larger cables can potentially drop the alternator load to as low as 42-44a.  Significant reduction in load and wear/tear on your alternator.

Hope this helps, @VonAustria.  Good luck with your install!

(*) We chose to use a Honda 2200 generator we had installed in the tongue/A-frame area (secured inside an enclosure) to perform charging duties while driving (vs. a dc2dc charger) and to provide full generator support while camping. Due to the high efficiency of the Victron Multiplus II 3000 charger we use, we're able to net 90-95a of charge current while only drawing ~13.5a from the Honda (prefer to run the Honda 2200 below its 15a continuous current rating).

pthomas745

@otr_320 Did you have a thread about doing this?  Or commented about it in an earlier thread?  I seem to remember some discussion about going into the trailer this way in the last couple of months.  Seems it would be very much easier than other threads that use the same "wire run" used for the cables from the junction box toward the rear of the trailer.

otr_320

pthomas745 said:

@otr_320 Did you have a thread about doing this?  Or commented about it in an earlier thread?  I seem to remember some discussion about going into the trailer this way in the last couple of months.  Seems it would be very much easier than other threads that use the same "wire run" used for the cables from the junction box toward the rear of the trailer.

I believe I mentioned it in a post 2-3 months ago, but didn't go into much detail.  It's a tight squeeze, but doable, at least on our 320.   

VonAustria

My initial post was just explaining what I wanted to do regarding installation of a 200 amp Renogy li Core inside my 2022 320 S BD along with a 2000 watt inverter. I’ve decided to install a 40 amp dc to dc converter inside as well. I’ve managed to find places to install the parts and pieces and now trying to properly configure the electrical integration after removing the factory installed lead acid from the tub and to bring the connection from the tv battery to inside the camper to attach to the dc2dc converter to fully charge the Li batt when I’m driving. 

I’ve reviewed all the information that others have shared in this forum and it’s been very helpful to say the least. I thank everyone that has responded and to those who have shared their experiences in times past.  

The dc2dc to me is important mostly to protect the alternator. I have a 2019 tacoma 4x4 off-road and I can SEE the alternator and sort of touch it. I can expect it is expensive but the labor cost  to replace it would make one weak kneed so to me the s
converter is simply insurance along with being able to fully charge the Li batt. 

HikerTravelers

routing wires from the trailer tongue to the drivers side and it wasn’t too difficult. My set up was a bit different than yours as my 30AH victron dc-dc charger was placed in the tub up front with charging wires running to the battery placed under the DS bench to a DIY 270AH lithium battery. 

I drilled a 3/4” hole through the floor under the bench. I screwed a standard square waterproof electrical box to the exterior of the floor, sealed with silicone.  The tongue wires run through waterproof seals into the box. While I was there I also ground the battery to the frame here as well. I used a large Anderson connector at the back of the TV to make the connection. BTW, we have a 2015 320css. 

You Definitely want to attach the charge wires to the battery and not to the alternator. I was able to add an “L”’ shaped lug to the existing battery connector and it looks stock. Don’t forget to add a breaker or fuse near the battery in the engine compartment. I added a 60 amp buss marine breaker so I can shut off wen not towing (so the Anderson plug at the back of the Pilot isn’t hot when not needed ). I’d also recommend you buy a quality breaker and not a cheap Amazon one. 

I did had troubles configuring the smart victron auto settings…the charger kept shutting down due to low voltage from my 2016 pilots alternator. I finally figured out all I need to do is keep the headlights on.  Now the the alternator consistently puts out 13.8 or higher voltage to trigger victron an auto on software. I also had to pull the 7 pin fuse on the Pilot because the charger was back-feeding to the Pilot. Hopes that helps. 

VonAustria

Thank you HikerTravelers for the response.  My trailer is a 2022 320S BD.  I bought it used so I have not dealer to lean on.

I have installed the Renogy 200-amp Core version on the passenger side under the seat cushions which is a close fit to say the least.  I put the Renogy 2000-Watt inverter nest to the a/c unit and the Renogy 30-amp dc2dc converter on the floor under the driver's side cushion.  I believe I will get an auto-switching relay for the ac voltage (I am old and forgetful).  Once I get this all finished and working I will share a few photos and how I resolved any problems I ran into during this modification.

The boondock version has a "cover" under the trailer that will have to be removed/let down to access the frame to route the wiring from my pickup battery.  I have already purchased the 4-gage wiring so I will likely use the black cable for the battery ground rather than the TV frame. Why did you decide to place the junction box externally under the floor rather than after you brought it into the cabin of the trailer? I assume you routed the wiring along the frame of the trailer. I have not dropped the "cover" down as of yet, so I don't know what access exists.
 
I read on one of the responses to add a device that contains a voltage controlled relay (don't remember what it's called) that will open and close between the tow vehicle battery and the dc2dc battery charger.  If the charging voltage from the tv falls below "X" voltage it will open the charging circuit.  This will prevent possible unwanted discharge of the tow vehicle battery. I'm guessing it is connected to the on/off control wire for the dc2dc box.

I am all new with this camping trailer adventure and looking forward to finding out how much I don't know.  Everyone who shares their experiences helps everyone so thanks for the suggestions. 

daizie24

Just came across with this but haven’t tried it yet.
Looks promising  & less complicated. 

VonAustria

I haven’t seen this type of system so I looked it up. It’s a lithium ion battery with a life if 2 to 3 years. It’s also subject to overheating. It’s probably a good alternative but I personally wouldn’t feel comfortable with it.