Anything missing from this wiring diagram for a TaB 320S lithium, inverter & solar port upgrade?

riseandshine

We're preparing for a big electrical upgrade including: lithium battery upgrade, inverter and charger install, external solar port install and relocation of the battery inside the trailer. Below is a wiring diagram for the project. I'd love to hear your feedback on the fuse and wire sizes, if everything look compatible, and any safety or functional issues. 

Also below is a summary of this project, our current usage case, useful links and a parts list.

Summary of the project:

• Replace two 6V lead acid batteries with a single SOK 206 AH LiFePo4 battery, moved inside the trailer under the front driver side seat near the WFCO converter. Move shunt and disconnect switch inside too. 
• Use Victron Lynx Distributor for simple and compact bus bar and fuse holder solution. The MIDI fuses will require a DIY copper adapter to fit the Lynx stud spacing.
• The low-profile battery disconnect switch and the shunt will be bolted directly to the Lynx bus terminals, to reduce wiring. All components will be fixed to plywood mounted to trailer's cabinets, including a DIY plywood battery retention box.
• 1200W Inverter install (Giandel Pure Sine Wave PD30W) next to AC unit under real passenger seat. NOT connected to WFCO for whole-trailer 110 - will be used with a power strip only.
• 30A Victron Smart IP22 charger install, next to AC unit under real passenger seat. Will be plugged into the trailer's interior 110 outlet for the AC, since we never use the AC.
• External solar port and charge controller install. The port and DC breaker for solar will be in the tongue box.
• The OEM WFCO 8735-P will be kept on the battery, even though it will no fully charge, it should not hurt the battery or interfere with the new IP22 charger.
• The old MPPT75/10 for the OEM roof solar panel will bypass the battery shutoff switch, for charging during storage.
• No routing of wire out of the trailer will be needed, instead Pos+ and Neg- wires from WFCO will be cut and the Lynx distributor will be connected in between. The old tongue box-WFCO wires for old solar and old WFCO-battery connection will be repurposed per the wiring diagram.

Usage Case:

• Trailer: 2020 Tab 320S Boondock with factory solar, factory WFCO 8735-P AC-DC converter, factory Victron MPPT 75/10 solar controller.
• Typical usage: 5 - 10 day boondocking trips in Western U.S., often staying in one place for 3 - 5 nights without tow vehicle charging. We rarely use shore power. We have not used the AC since buying the trailer in 2020.
• Sun exposure: typically good partial sun each day, except for overcast weather periods, where current batteries get close to 50%.
• Electrical usage: Continual 12V refrigerator use on all trips. Laptop & camera charging. No AC usage and no microwave. With new inverter we'll use small appliances infrequently for short periods, and 800W hair dryer maybe 5 minutes every other day.

Wiring diagram:

Full-size wiring diagram:

https://photos.app.goo.gl/72idtoEQmRp3GDmC8 

List for most parts:

https://www.amazon.com/hz/wishlist/ls/1M6WI1IDWDNU5?ref_=wl_share

Battery:

https://www.currentconnected.com/product/sok-sk12v206-lifepo4-battery/

Links that I found most helpful:

Choosing the Correct Wire Size for a DC Circuit:

https://www.bluesea.com/support/articles/Circuit_Protection/1437/Part_1:_Choosing_the_Correct_Wire_Size_for_a_DC_Circuit

Lynx Distribution with midi fuses?:

https://community.victronenergy.com/questions/54614/lynx-distribution-with-midi-fuses.html

DC Junction Box, Breakaway Brakes and Battery Disconnect Switch (T@B 320):

https://tab-rv.vanillacommunity.com/discussion/9774/breakaway-brakes-and-battery-disconnect-switch-t-b-320

Lithium Charging voltage details:

https://tab-rv.vanillacommunity.com/discussion/comment/197082#Comment_197082

WFCO WF-8735-AD + LiFePO4: FYI on annoying 'auto detect' quirk:

https://tab-rv.vanillacommunity.com/discussion/16210/wfco-wf-8735-ad-lifepo4-fyi-on-annoying-auto-detect-quirk/p2

Replacing AGM with lithium in 2021 tab320 BD:

https://tab-rv.vanillacommunity.com/discussion/17897/replacing-agm-with-lithium-in-2021-tab320-bd/p1

How to Wire a Solar Disconnect for a DIY Camper Electrical System:

https://www.youtube.com/watch?v=HOXnWXvLXko

How to Crimp Various Electrical Wires: Beginner and Expert Tutorial:

https://www.youtube.com/watch?v=dTYyMwbSK7I&t=519s

Offgrid Solar Inverter Buyer's Guide for Beginners:

https://www.youtube.com/watch?v=1rxSapfp4Hs

New Battery! Marine Grade SOK 12V 206Ah LiFePO4 for $.39 per Wh:

https://www.youtube.com/watch?v=zJmIS5tmzPU&t=364s

bjn2

@riseandshine I can't make out the positive side connection to the Smart Shunt but assume that involves the unshown battery connections to the Lynx. Note that in our 2023 trailer, the trailer brakes get battery power via a branch wire tapped into the main OEM battery connection wire to the tub. If I interpret your drawing correctly, you're maintaining power to the OEM tub wires, which would keep power supplied to the brakes assuming yours are wired like ours. I mounted the OEM trailer wire to a pair of post isolatin studs. I've reused the tub's solar wiring to add a solar port to the side of the tub. I extended the wires inside the trailer to a second Victron solar controller.

I put an EMS-HW30C surge and electrical protector behind my WFCO box. I'd really have to move stuff around to squeeze in my lithium battery, shunt, external solar port controller, fuses and breakers. I have a Victron charger and have wired in their quick connect. I like your idea of using the under-seat AC outlet for the air conditioner to plug in my charger, but I'll see if there's space to use one of these: https://www.amazon.com/Conntek-RL-30104-3-Prong-Outlet-Adapter/dp/B00BHGY37C?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=ATVPDKIKX0DER

Rather than bother with adding an inverter to the trailer, I got a Bluetti AC180 during the holiday sales and will use that for any minor amount of AC use we'll need. The Bluetti's versatility and portability make some sense for our envisioned uses, including a multizone DC cooler for our tow vehicle. If I didn't already have a 100AH lithium battery, I'd have opted for one of the newer 200+ AH options for the trailer. 

riseandshine

Sounds like a nice upgrade bjn2. You are correct: power is being maintained to the main OEM tub wires (and the 7-pin junction box on the underside of the trailer) via circuit # 3 on the Lynx. The Lynx distributor has both a Pos+ and a Neg- bus bar inside (hidden in the diagram) - it contains four MEGA fuse holders integrated into the Pos+ bar. The EMS inside the trailer is an elegant solution, but we already have a portable unit (Power Watch Dog PWD-30 EPO). As for space being tight under the seat, you're right, the measurements show it all fitting, as least as of now :-) And regarding the Bluetti: we love ours too, but it takes up a lot of room on the floor of the trailer.

riseandshine

Has anyone had trouble fitting 10 AWG wire with ferrule crimped ends into the Victron SmartSolar MPPT 100 | 15 12/24 V Solar Controller? I found one review that said 12 AWG with ferrule ends is the largest that fit.

Maxcamp8

Wow.  You've done your research and an impressive thorough diagram.  Wish I was as organized on my similar retrofit underway.  Will have to look into this Lynx for space optimization.
Comments I received that might apply to your layout as well: 
1. Would a DC shutoff switch between Lynx and Inverter be beneficial for maintenance reasons?
2. Minor point, are there additional ground connections needed at various equipment?  I didn't draw all of mine either.

Your  surge protector is important.  We camp on shore power less often now, but our hardwired PWD30 has protected us from severe undervoltage at a stunning number of about sites (below 112 to 114v AC).

Trying to build in: 
- Robustness against wire pullout or damage. 
- Cable slack to ease installation and future maintenance. 
- physical separation of 120v from 12v wiring.  In buildings they cannot cohabit.
- labeling for future reference 

I have moved and rewired most of Nucamp 120v work for layout and safety.  Just say no  to snap-together RV duplex outlets in water compartments.

Spent hours today modifying a new 2000w inverter to accept 10awg output feeders and made wire strain relief device.  Underfit terminal design.   Sounds like you encountered something similar.

Look forward to seeing and reading how it goes!

riseandshine

Great points Maxcamp8. A second disconnect switch could be installed easily and inexpensively on the Pos+ wire going to the inverter, so I'll add that to the diagram. And before this project is finished all the wires will get labels, even the OEM DC component wires, so we know which fuses affect which trailer components.

Regarding ground connections, the inverter manual specifically says to ground it. The only other component that has a ground connection is the Lynx distributor. Victron's manual says that grounding "only applies if the system requires a ground connection. There should only be one ground connection per system". The WFCO is already grounded, and the Lynx is hard-wired to the WFCO via circuit # 3. And the inverter will be grounded to the WFCO's ground wire to avoid a "ground-loop", or multiple ground points in the system. So, I'm unsure that grounding the Lynx is required, but it's an easy add-on if needed. I'll learn how to connect one bare copper ground wire to the middle of another, to connect the new ground wires to the exiting WFCO ground wire.

As for rewiring the OEM 120V wiring, what all did you do? I'm unfamiliar with the snap-together RV duplex outlet issue. I would LOVE to add more slack to the 110V wires connected to the WFCO, as they take up a lot of space under the driver side seat. Would you splice these wires to make them longer, or replace them with new longer Romex 10 gauge wire, rewiring from each component (shore socket, AC, Alde, trailer outlets) to the WFCO?

Regarding physical separation of 120 and12V wiring, that issue never popped up in my research. The main issue appears to be DC wire magnetic fields messing up the sine wave of a nearby 110V wire. It also appears that as long as the AC and DC wires are not touching and are separated by a thin divider, that should solve the induction problem. I'll use 1/2" plywood or sections of cable cord hider to separate AC and DC wires wherever they come within a few inches of each other, especially on the inverter and charger cables.

The system has no built-in surge protector, but we always use a Power Watch Dog PWD-30 EPO when hooking up shore power, even at home. It's a high quality protector with replaceable surge/spike module, and we have a spare module.

Regarding wire pull out and damage, properly use of lug and ferrule crimping techniques will hopefully make this system robust enough for a mobile RV. And everything will be fixed to plywood that's in turn fixed to the trailer's cabinetry. I'm wondering if the components should be attached to the plywood with small rubber spacers to absorbs some of the shock from road travel, or if that would be detrimental.

As for cable slack, that's a great suggestion. I'll measure using the actual cable and include enough slack for easy install, easy battery removal in winter, and to allow wire drip sag to protect components from any drips onto the wires from either glycol, a leak, or a drink spilled on the seat cushions. Thankfully the Lynx has a cover in case there are any exposed bits of wire near the terminal ends.

Maxcamp8

Link to prior work.  Yes I did full 120v rewire.
Worked on the Wefco up at waist level sitting on stool, coiled slack for install.  Too compromised to grovel down at floor level for long.

https://tab-rv.vanillacommunity.com/discussion/4388/pd-4135-installation#Comment_182995

subfreq111

Sounds like you use your 320 similar to how we do. I haven't plugged into shore power since installing our system 4 years ago and never need to mess with a suitcase. Power is just a thing we don't have to worry about. We are always at 100% from solar charging on the highway and the 12v fridge takes us to about 91% overnight but we are topped off again by 10am. We have 530W of flexible panels on the roof, 340Ah of lithium, and a 3000W inverter. 

Here is a link to my install with some pictures

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

riseandshine

Thanks Maxcamp8 for the rewire post. Wow subfreq111, that's a lot of solar - I suppose that's next on the project list if the suitcase doesn't cut it! 

RCB

This RV electrical stuff is getting pretty complex, especially for us rubes. Thanks, I’m learning.
Question please. Can someone post a pic of the Nu Camp solar disconnect now in use ? My 400 is a 2019 and does not have one.

riseandshine

Update: the project is complete and everything in the new electrical system and all other T@B electrical items are functional. Below are photos of the install and several comments that fellow upgraders may find helpful. This was a bigger project than anticipated, but well worth the cost and time. The wiring diagram was modified from what was originally posted, so the final version is shown further below. 


Photo 1: Battery compartment under the driver side front seat. Below is the main install area, with battery, shutoff switches, smart shunt, both solar controllers, solar cutoff switches, and the Lynx power distributor, plus the OEM WFCO converter.


Photo 2: Closeup of battery compartment left side. Below it's easy to see the roof solar and solar port shut off switches, the main battery shut off switch (red, top) and the inverter shut off switch (red, bottom).


Photo 3: Cooling fan controller and updated 110V outlet in Alde compartment under driver side back seat. The cooling fan is set to turn on at 90F with the temperature probe in the main battery compartment near the solar controllers. The battery has it's own BMS for internal low and high temperature protection for charging and discharging.


Photo 4: Inverter, charger and updated 110V outlet in AC compartment under passenger side back seat. Since we never use the AC, all three AC hoses were disconnected and pushed out of the way, freeing up a lot of extra space in this compartment.


Photo 5: Inverter power strip and on/off switch panel, to right of WFCO fuse box. Below shows the panel installed near the floor that runs the inverter outlet. The OEM shore power 110V outlet that used to be in this location was bypassed and removed, freeing up room for this new inverter panel.


Photo 6: Solar port installed under driver side of tongue box. Sturdy, out of the way and fairly easy to access, this port install required no metal drilling, using pre-existing holes in the bottom back side of the tongue box.


Photo 7: Junction box inside tongue box for unused OEM wires that used to connect to batteries. This is to keep the old wires in place safely, just in case there's a future need for them. This waterproof box also contains the old 4 pin connector for the previous smart shunt location. 


Photo 8: Access door that was installed in the bathroom for easy access to the glycol reservoir. This is one of the BEST mods I've made to this trailer. This access door looks great and was easy to install, after getting the sizing and position of the cutout just right. Saves a LOT of time and hassle when you want to view the glycol level (or add glycol), which seems to happen every trip.


Photo 9: Glycol reservoir access door opened. The door is sized and positioned to allow reasonably easy viewing of glycol level, and just enough room to pour glycol into the reservoir with no need for a funnel or tubing.


Photo 10: Closeup view inside the glycol reservoir access door, with battery powered LED puck light inside. The puck light turns on and off when you push in on it and lights up the compartment very easily and well.


Final Version of Wiring Diagram:


Comments:

• This entire project took about 5 days, 6 to 7 hours per day, after preliminary measurements were worked out. 
• 80% of the time and effort for this project was consumed by planning and making space for all the new components and designing and installing ways to attach all the components.
• One day's time is all that was needed to install and connect all the 12V wiring for all the components.
• The Lynx distributor saved some time and space in some ways, but added extra time and work in other ways. The included washers and lock washers had to be ground slightly on one side so they would not interfere with the MIDI fuses bodies. Copper extension plates were needed to fit MIDI fuses into the Lynx, being careful where the holes are to fit the fuses properly. The MIDI fuse lugs/holes had to be carefully reamed larger to fit onto the included Lynx bolts.
• The cooling fan was installed just in case it gets too warm in the battery compartment for efficient solar charge controller operation (100F or higher). It has not gotten that warm in there yet, but it's a nice insurance policy just in case.
• The SOK battery is mounted on its side, which is safe according the the manufacturer and according to Current Connected, the seller of our battery. There a shallow wooden battery box screwed to the floor with foam bottom and sides for the battery, but it's hidden in the photos.
• Programming all the Victron components with the correct specs and networking them all together took 2 or 3 hours. Fortunately, Current Connected has very detailed webpages for all the settings for most Victron components for the SOK batteries.
• Lastly, this was a tremendous learning experience. Coming into this project with minimal basic electrical experience, I learned a lot about 110 and 12V safety, function, equipment and installation. These are great skills to have for future use, and it's great to be intimately familiar with your RV's electrical system.

Maxcamp8

Nice job @riseandshine! Impressive planning and creative use of space and fitup.
Like the use of DC breakers, have to look into these rather than a kill switch on the phantom draw of the solar converter when not in use.   

RCB

How is the TV alternator protected from overheating when the Lipo battery draws a large amperage ? The 7 pin accessory is limited by an in car fuse. In my case the entire 7 pin has a 30 amp fuse. The wiring to the 7 pin  is as well sized to this load. I understand the 7 pin accessory wire is probably limited to about 10 amps. So how is this charging system protected when the battery is low and is hungry for amps ?

riseandshine

Good question RCB. From my limited research into DC tow vehicle charging and alternator damage due to RV lithium battery current draw, it seems this is only an issue with upgraded DC-DC charging systems and upgraded cable that are designed to carry more amps. With a traditional 7 pin connector, this should not be a problem. I have yet to measure the amps coming in from the 7 pin connector, but plan to do so soon.

A short video about this from Battle Born Batteries:

https://youtu.be/Gxypk8J-0Mg?si=61W1gzsw1F2kj-MX

A demo of low amperage through a standard 7 pin wire:

https://youtu.be/WblbzIQgNRE?si=rbJUtCHqHROxwRbz

Yoshi_TAB

Hi @riseandshine

A couple of questions in an effort to learn more.  I have a similar setup with slightly different wiring and a few other differences.

1.  Why do folks put breakers in between the solar controller and the panel or solar plug.  Why don't OEM suppliers (i.e NuCamp) also do it?

2.  Did you tie in your victron charger to the lynx distributor as a way to connect to a positive  busbar or did you want also fuse protection on the DC output of the charger? 

3.  What does your cooling fan cool?  Victron charger or inverter?  Does it come on at a certain temp. 

TY

Marceline

Yoshi_TAB said:

A couple of questions in an effort to learn more.  I have a similar setup with slightly different wiring and a few other differences.

1.  Why do folks put breakers in between the solar controller and the panel or solar plug.  Why don't OEM suppliers (i.e NuCamp) also do it?

This is how Bay Marine Supply explained it to me: 

"A fuse or breaker is required on the +ve circuit between the controller and the battery, yes. While another fuse or breaker between the panel and controller is not required by code until you get 3 or more parallel strings running into the controller, we do suggest that some kind of disconnect be installed there in any case just so that you can isolate the controller should you need to, without waiting until dark or climbing around covering your panels."

Since I'm using a portable panel that I plug into an SAE port between the controller and the panel, I don't have a breaker/fuse there as I can just unplug the panel the cut the power supply from the panel to the controller. It sounds like it would be a good idea to have a breaker/fuse if you have panels permanently mounted to the roof of your T@B.

riseandshine

Hi Toshi_Tab,

1. The breakers are being used as simple disconnects rather than breakers. This is to comply with NEC 2020 Article 690.13, which may not be needed for RV's but seems like a good and simple to implement idea, just in case. It's also nice to quickly disconnect solar sources from the system to measure the draw on other RV components, such as furnace or fridge. The code states "Means shall be provided to disconnect the PV system from all wiring systems including power systems, energy storage systems, and utilization equipment and its associated premises wiring." Links:

https://up.codes/s/photovoltaic-system-disconnecting-means

https://www.youtube.com/watch?v=HOXnWXvLXko

2. The charger is dedicated to circuit no. 2 on the Lynx distributor with a dedicated 40 amp midi fuse. The charger is capable of 30 amps, but I manually adjusted the settings to 20 amps max, as it's plugged into a 20A 110 outlet in the RV (when on shore power), and it also runs much cooler at 20 amps versus 30. If I'm at home, I can run a 10 gauge extension cord from our home's 30 amp washer/dryer room outlet to the RV and run the charger at 30 amps, but there's little need as 20 amps charges plenty fast.

3. The cooling fan is for the solar controllers and battery compartment. It's easy to install, cheap and programable per the video below. The solar chargers are supposed to run at temps below 100F for best efficiency. The fan is set to turn on at 90F. Since we don't know how hot it may get inside the battery compartment when running the Alde heater on a cold night all night long, a fan seemed like a good idea. But at night there's no solar charging, so that issue is gone. And during the day when we may use the inverter and cause battery heating, the Alde should be off. And even if it gets over 100F, the BMS in the battery has internal low and high temperature protection. So far, running the heater at 80F for a few hours has not caused a heat problem in the battery compartment. We'll monitor the temperature closely on our first few trips and see if the fan ever turns on, and if so, how well it works.

https://www.youtube.com/watch?v=srxYjc9nJao

FYI, the charger and inverter are in a separate compartment away from the solar controllers and battery. The charger only puts out moderate heat at 20 amps, as mentioned above. And the inverter, even running a hair dryer at 50 amps (low heat setting) for 5 minutes, surprisingly puts out negligible heat.

riseandshine

UPDATE: Below are some observations after our first week-long camping trip of the season:

1. Everything in the new electrical system worked well, actually better than expected. This trip included over 1000 miles of trailer travel, with a mix of interstate, mountain passes, and 40 miles of bumpy, dusty and sometimes muddy dirt roads in the Wedge area of Utah.
2. The inverter was a big hit with Michelle, who used it for drying her hair after her evening shower and prevented her from getting cold in the evening due to a wet head. The hair dryer only drained the battery 0.5% on each use and the inverter never got hotter than lukewarm to the touch.
3. We used the inverter more than we thought. It simplified things with no need to recharge the laptop, phones and tablet inside the truck while driving. 
4. The temperature inside the battery compartment never exceeded 85F, so the cooling fan never kicked on. The hottest times were in the evenings when the Alde heater was running most. Lowest outside temperatures were around freezing on this trip.
5. Even after a few days with mostly cloudy skies and normal electrical usage (refrigerator, laptop charging, brief hair drying, evening lights, fan, etc.) the battery never fell below 65% SOC (discharge floor is set at 10%). It was really nice to have plenty of excess power and not be concerned about running too low, as happened often with the old lead-acid deep cycle batteries.
6. The solar port and 120W briefcase solar panel was a big success, with one glitch. When the sun did come out, it really sped up the charging and outperformed the roof OEM solar most of the time. The port connection was very tight and hard to plug into, likely due to expansion of the plastic in the heat (the new electrical system was installed during cool weather). Some adjusting of the solar port and/or the briefcase plug will be needed.
7. Despite the fact that Michelle is sensitive to odors, she noticed very little "hot parts" smell from any of the electrical components. One exception was the inverter, which put a little bit of "hot electrical" odor into the trailer, but it was mild.