2021 T@B 320 Wiring Batteries

Clipper_One · October 2023

When upgrading to single or dual Lithium, and moving the batteries to the inside cabin in different locations, some members are running a conduit with #8 or #10 wires to the front tub, It would be a lot simpler and cleaner to run the wires internally directly to the WFCO, and other related components.

I wonder if there is a reason why no one attempted these method?

I know that it simplifies the installation by running wires to the front tub and leaving the switch and wires in place for future use, however running the additional wire length would affect the amperage by the added wire resistance thus affecting charging as well.

I have requested from NuCamp the 2021 Tab 320 S, and they answered that they do not have a wiring diagram.

Since NuCamp does not provide the wiring, I will try to figure it out myself by ringing the current wiring in my Tab, then draw a wiring diagram based on my tracing, additionally I will add the dual lithium wiring installation under the pax bench seat.

Any comments, ideas, and suggestions would be appreciated.
Thank you,

ScottG · October 2023

I see no reason why you couldn't do this. In fact, running new wires between the interior benches sounds a lot easier than running new wires from the WFCO to the tub (been there, done that...). You would just need to run your battery (-) into the DC ground bus, and splice your battery (+) into the existing line from the tub. You could (and probably should) mount a new cutoff switch next to to the WFCO.

The one caveat I would add is to NOT disconnect the existing battery lines from the power center to the front tub. Assuming your 2021 is wired similarly to my 2015, these wires run through a forward junction box that also connects them to the pigtail (to allow charging from your tow vehicle) as well as to the breakaway brake system (which draws power from the house battery in the event of complete trailer separation). If you relocate the battery to the inside, you will want to make sure those connections to the forward junction box are maintained.

Image: https://us.v-cdn.net/5021717/uploads/editor/b6/2cvyv4ydrema.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/ix/1fz19e76fx8p.jpeg

SLJ · October 2023

You could just run the wires to the controller inside. That would work. I also could not find a wiring diagram and I don't think anyone else had documented a move yet so I ran a new set from the tub so I could easily add a third battery back in the tub location if I thought I needed it (I don't) or wanted to put the wiring back to original. I also wanted to be sure the original cut off switch would still keep the solar connected. It wasn't that much work to just run flex under the floor. An original wiring diagram would have been nice to find but NuCamp isn't known for their documentation.

Image: https://us.v-cdn.net/5021717/uploads/editor/sj/h40k2npom8pl.jpg

Clipper_One · October 2023

@ScottG
That’s my thought as well, I am planning on leaving the existing tub wiring as is for future use. I will also add a new cutoff switch on the outside of the pax bench, I am looking for a low profile switch in Amazon. Once I get the wiring done, I will document everything, and generate/draw a wiring diagram with the associated components.

I believe this will help me and others troubleshoot any future electrical issues, specially members who owns the 2021 T@B 320 S BD.

Thank you ScottG

SLJ, has been very helpful in providing me with the information related to his dual batteries upgrade mod, I really like his mod so I have purchased all of the components required. I will post the pictures of the end product.
Thank you SLJ

Yoshi_TAB · October 2023

Hi,

I installed two lithium batteries in front of the Air 8 in my '21 without cutting any new holes, without running any new wires from the outside and used only internal wiring. I abandoned the wiring in the tub. I still have the external solar plug. To do this, you can splice into the battery wire from the WFCO that goes out to the compartment in the trailer front. I installed a new battery switch inside (in addition to what is shown in the photo). I also installed an inverter and transfer switch. Let me know and I can provide more pictures and wiring diagram. You can use either location but the storage under the passenger seat was more valuable to me than the space in front of the Air 8. It was also closer to the inverter, making the wire run for the large AWG shorter. The inverter and transfer switch were placed where the WFCO is.

I also wired the batteries directly to the the electric brakes, independant of the ON/OFF battery switch, so they always have power and there is no worries if the switch was mistakenly turned off while towing. That is important to me for a safety device.

Image: https://us.v-cdn.net/5021717/uploads/editor/bb/1uljlakxayjv.jpg

Clipper_One · October 2023

Hello, Yoshi_Tab

It is very nice of you to offer, I will definitely take you up on the offer, if you have the wiring diagram, and detailed pictures it would be very helpful. I am wondering if having the batteries next to the Air-8 would make a significant shift of weight towards the rear, possibly causing towing problems and it may cause a lighter tong weight.
I like the idea of mounting the batteries under the pax bench because it is over the axel maintaining the center of gravity with no weight shift. I need to stop thinking Aviation!

Yoshi_TAB · October 2023

@Clipper_One

Hi, The batteries are so light, I can't imagine the weight of them by the Air 8 causing an issue. The weight of each of my batteries is only 21 lb. I've towed about 28K miles with this set up. But obviously, do what ever your comfortable with. I know NuCamp has put them in this location for some aftermarket upgrades. Also, it made my wiring to the inverter/transfer switch much easer.

Here are two drawings. The top one is generic of how to move the batteries inside without needing to run new wires outside. It's quite simple. The top drawing is split by OEM and the change . The drawing below the dash line is the detail of my particular setup. Hope it helps give you ideas. Ask any questions you may have...

The #6 wire from the WFCO is the one that runs from the WFCO outside to the junction box (and then to the battery). You cut that wire behind the WFCO. The one end from the WFCO will now go to a new battery ON/OFF switch installed inside (I placed it near the WFCO), to a bus bar and then to the battery(s). The other end of the cut wire (which goes toward the bathroom and outside) also gets connected to the bus bar. This way, the trailer emergency brakes always have power indpendant of any switch. The power to the WFCO can be turned on/off with the new switch installed.

(On a side note, I see your in Port St. John FL., I may be heading down that way in about 6 or 7 weeks to visit my parents in Vero Beach. I'm on the fence of taking my TAB. If I do, maybe you can see it which always helps)

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Image: https://us.v-cdn.net/5021717/uploads/editor/6h/nv3o2945ned4.jpg

Clipper_One · October 2023

@Yoshi_TAB
Hello,
You’re so right, I never thought of the Lithium light weight, so it shouldn’t be an issue. Question, Have you placed any shock/vibration pad beneath the batteries?

I purchased a couple of the pads to prevent internal damage to the cells, just in case.

Since you opted to installed the batteries next to the Air 8 unit, have the batteries interfere with the AC return air pathway if mounted directly on the floor?

Do you have a Solar roof panel, I do not see the Roof Solar Panel depicted on the diagrams, I do see the tub external plug, however it is hard to read the rest of the component block name.

Thank you so much for the pictorial wiring diagrams and information, now you got me thinking about installing a 2000W inverter myself, what brand is it?

Please send me an email message letting me know when you are headed down, we would like to see your T@B battery upgrade, if possible.

SLJ · October 2023

His roof solar panel would be connected to the Victron converter in the upper right of his diagram.
I considered putting the batteries next to the Air8 but decided the 44 pounds would be better directly over the axle. I do a lot of bouncing on fire roads when boondocking. I can still store stuff next to the Air8 which is easier access for me anyway as I have my table located over the passenger bench most of the time so the seat over the Air8 is easier for me to flip up.

Yoshi_TAB · October 2023

@Clipper_One

Hi,

-I did not place any shock /vibration pads. I follow a bunch of Vehicle /RV DIY solar/electrical forums and don't recall anyone using such items. They are not used in the front tub with the OEM setup. Batteries are designed (or should be) for environments such as RVs, boats, etc that take a lot of abuse. IMO this also makes the difference in quality of components and construction between higher and lower cost batteries. I have seen a few breakdown of batteries and if you watch them, there is differences in cases, parts, construction, etc. I used this as battery holddowns: Amazon.com: Camco Camper/RV Standard Battery Hold-Down Tray | Holds 24/24M Automotive Batteries | Fits Batteries Up to 11 1/8" L x 6 ¾" W x 8" H (55394) : Automotive

-There is no change in to the Air 8 return or supply air flow path. In my set up, there is nothing additional in front of the return air, and only the the supply air duct was moved on top of the batterties vs. laying in front. We took a late spring trip to the US SE and used our Air 8 for about a solid month toward the end of the trip and it ran just fine.

-Yes, I have the roof top solar. There was no change to that circuit, other than putting the negative wire on a newly installed negative bus bar. (see below in pitcture). Same for the external solar plug.

- Here's a photo of the inverter/transfer switch. It's a bit tight, but all fit. I used a 2000W Renogy. Probably a tad larger than what I really needed, but it fit nice. I know some folks are microwave haters in a camper, but its nice to quickly heat items up for a minute or two. We also use a hot water kettle for our morning coffee

(1400W) that only takes a couple of minutes to heat up. Most inverters come with a remote switch which I placed next to the Jenson. Fished the wire (for the remote) up to behind the microwave and over to the Jenson. It's easily reached from there. The most important thing when installing an inverter is sizing wiring and fuses. Fuses are sized to protect the wiring, not the device. I ended up using 2/0 AWG wire and a 250A class T fuse. I bought premade wire with ends from Windy Nation. They have high quality wire and sell on Amazon. Getting the pre-made lengths was tricky and I had to return a few and get new. As you know, Amazon makes that process very easy.

-If using a transfer switch , you also need to make a wiring change so when running on battery power, the battery charger is not charging the battery from itself..if that makes sense. Some folks will add a new circuit breaker into the WFCO (split the last one) . As delivered. the battery charger portion of the WFCO is wired into circuit breaker #2.  I moved the wires from there into the transfer switch so it only charges on shore power. Some folks will add a new circuit breaker into the WFCO (split the last one) and wire the charger there so it can be turned off when using the inverter. Lastly, since the compartment is small even though the inverter has an internal cooling fan, I added a small computer type fan right next to the inverter and it only comes on when the inverter is powered. I mostly use the inverter for low power devices (except when usng the microwave or kettle for short periods of times).

I know this may sound complex...but if planned out it's not if you feel comfortable doing DIY electrical wiring. I'm happy to answer more questions or send photos. Here are of the sites that were most helpful to me; Vehicle Mounted Systems | DIY Solar Power Forum (diysolarforum.com);  EXPLORIST.life - Home;  DIY RV Solar Systems | Facebook

Image: https://us.v-cdn.net/5021717/uploads/editor/a0/eq7n27p8ic1f.jpg

AnOldUR · October 2023

An off topic question @Yoshi_TAB. I may have stolen your inverter mounting method. Looking at your picture I noticed no ducting for the AC outlet on the bath wall. Is this a change between 2020 and 2021? Do you have an AC vent up by the Alde control panel?

Image: https://us.v-cdn.net/5021717/uploads/editor/zo/kx6lcvz9lq0t.jpg

Yoshi_TAB · October 2023

@AnOldUR,

Ha...actually I stole yours. Did I forget to say thank you

You were a month or two before I did mine.

The AC duct is under the inverter (very hard to see) and goes through the opening (at the floor level) & up the wall. I placed a couple of small wood standoffs (glued to floor) under the inverter to provide support to the inverter and make sure the duct does not sustain any damage. I believe there was no change to the Air 8 duct locations.

AnOldUR · October 2023

Yoshi_TAB said:

You were a month or two before I did mine.

I must gotten the idea from somewhere else. I spend way too much time browsing this forum and FB groups.

On closer look, I do see the black AC tubing well hidden under the inverter. Looks good!

Clipper_One · October 2023

@Yoshi_TAB
I have to say you’re the best, excellent ideas, pictures, diagrams and Q&A’s, so I guess I’ll be copying a little bit from each of you, and applying some of the suggestions and, I will definitely take you up on asking questions I’m sure I’ll be running into some issues from time to time.

I am so excited to get this upgrade done, I retired two years ago and since I did not retired to something, this baby will keep me entertained for a while until I get it done.

Thanks
Carl

AnOldUR · October 2023

SLJ · October 2023

Clipper_One said:

until I get it done.

My first and most important mod was the wife's demand for a bathroom fan. Once I figured that one out I was free to tackle all the ones spinning around in my head in the order of my perceived importance. I have completed all of those over the past two years and am planning just a couple refinements of already completed projects after using the T@B for a couple of seasons. Nothing more on a major scale... yet.

Clipper_One · October 2023

I guess I need to be more careful with my choice of words.

Sorry guys!

bjn2 · October 2023

I decided to move my Dr. Prepare Powermax battery and my Smart Shunt from the tub to the interior next to the passenger side seat/bin. The idea is the battery will stay warmer inside the trailer and therefore accept more solar charging when it's cold out. I'm not going to futz with a battery warmer.

The discussion and images in this thread are very helpful. On our 2023 320s, the power cutoff is located on the front of that passenger side compartment, so I just detached the OEM wires there and will reuse that switch with the new 8 AWG wire I'll use for the short run over to the controller and ground bus.

In our bin, there are two fused sets of OEM wires that connect to the battery. One is for the trailer's main power circuit and the other comes from the Victron solar controller. But there are two negative wires crimped together at the lug for the main power. I need to figure out where the second negative wire comes from. Perhaps from the tow wiring junction box.

I think I'm going to take advantage of the hub device for the Powermax battery and install a port to hook up a portable solar panel via that hub. The hub can handle 100w of of solar, and I think I'll put an SAE-type solar port in the wall near the battery. I'd rather have another Victron controller with Bluetooth controls, but for the money I've decided to use the stuff I already own. I'll have to run new wires from my Victron solar to the battery, but that's also a short and easy interior run.

Rather than undercharge from the WFCO "never detect" controller, I have a Victron Blue Smart IP65 12-Volt 15 amp battery charger that works great and I can plug into the AC outlet under the dinette seating.

Yoshi_TAB · October 2023

HI,

That is correct for the neg (and pos). wires (they run from the bin to the trailer junction box and then inside, at least on a '21). Now that you have spare wires in your front bin that run inside, as an option can you mount your portable solar controller in your front bin along with an exterior solar plug there. That is what I did.

rickpool · November 2023

@Yoshi_TAB - Thank you for your wiring diagram and for all your insight. I am still learning here, but wouldn’t the electronic brakes get their power from the tow vehicle while it is being towed? If so, would it be unnecessary to separate the brake wire from the switch?

Yoshi_TAB · November 2023

Hi,

Yes, the trailer electric brakes do get their power from the tow vehicle (while it's connected via your 7 pin tow harness) which is modulated by your brake controller.

The reason the battery comes into play is in the unlikely event your TAB becomes totally seperated from your tow vehicle. At the same time your TAB becomes seperated, the pin ( connected with a thin cable to your hitch) is pulled to activate the electric brakes. When the pin is pulled, the battery then sends the power to the electric brakes to turn them on and bring your TAB to hopefully a safe stop without causing any damage to other vehicles or people. Of course, this involves mutliple failures (off ball hitch, failure of safety chains, 7 pin becomes disconnected) so it's unlikely, but possible.

I seperated the electric brakes because if the battery switch is mistakely left off, there would be no power to the electric brakes for them to work. In my other life , I do safety hazard anaIysis, and counting on a human to perform an action for a safety device is at the bottom of the ways you protect your system when you can "engineer out the failure". I know it appears my set up is "hotwired", but I do have two fuses in line that can be pulled if I need to disconnect power from the e-brakes.

hope this helps...

subfreq111 · November 2023

I also moved the whole system completely inside and use the front tub to hold an extra 20# propane bottle.

https://tab-rv.vanillacommunity.com/discussion/10902/just-another-solar-lithium-install/p1

rickpool · November 2023

Still a newbie here… am investigating switching my 320 over to 2 LiTime 100 ah Minis. Understand I need to use 10 gauge wire, but not sure whether to use 30 or 50 amp fuses (have seen both used in schematics). Which is appropriate?

rickpool · November 2023

Oops… I just read 10 awg is rated for 30 amps, so the 30 amp fuse is the right answer. Sorry.

rickpool · November 2023

@Yoshi_TAB - Excellent schematic (and now I am sucked in!). Can you please confirm what wire gauge you used connecting your batteries to the positive and negative busses? The schematic seems to say 20 AWG which I am thinking is to be read as 2/0 AWG? And everything else is 10 AWG unless marked, right?

Yoshi_TAB · November 2023

Hi @rickpool,

I used 2/0 AWG only because I have an inverter in my circuit. If you don't have one, you can get by with much smaller wire. An inverter circuit needs to be protected with a high amp fuse (depending on the size of the inverter...225A/2000W in my case). If you do not have an inverter you do not need the large of wire.

I used 10AWG for all other circuits (than inverter), which for 30 amps is fine.

Good luck with your project...

rickpool · November 2023

@Yoshi_TAB - Thank you for navigating my trip down this rabbit hole! :-) I will go with the 2/0 gauge for interconnects to make it easier to upgrade to an inverter as a future project. But I do have 1 more question… your schematic seems to show a positive 2/0 wire going into your inverter, but only a 12 AWG wire going from inverter to the negative bus bar. Is this a typo, or is there yet more for me to learn? I am thinking we would need 2/0 gauge all the way back thru the bus bar, thru the shunt, and to the battery on the negative side as well? As always, I look forward to your enlightenment! Thanks!

Yoshi_TAB · November 2023

Hi @rickpool,

Yes, that is a typo. It is 2/0 AWG wire.

Also not shown is the 110V wire size from the inverter to the transfer switch. I used 12/3 SJOOW wire which is wire inside a rubber sheath, like a heavy duty extension cord. Since the transfer switch only feeds 20 amp AC circuits, 12/3 is adequate. The flex wire was much easier to work with in the space in between the transfer switch and inverter.

I'm sure you know..but keep an eye out for cheap knock offs on Amazon for fuses, wires, busbars...spend a few more dollars and get name brand parts. I got my cable from Windy Nation. If you do a good job with measuring, you can get pre-made lengths with terminals already crimped on. If not, they are easily returned for what you need. I used a string to help measure my lengths. One other "pitfall" to watch out for is the crimped terminal ends come in two standard diameters (3/8" and 5/16") and I found my battery terminals, busbars , switches & fuses mixed up with the two different sizes depending on their amp capacity. One end of a cable may need one size and the other end may need another size depending on what you are connecting to.

Keep asking..

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