RV Power Center: Lynx Distributor Modification

This post is the fifth of an ongoing series of articles documenting and describing our RV electrical upgrade. Our previous post in this series described creating the physical space for our power center, initial wiring, and solar upgrades. In this post, we describe the Victron Energy Lynx Distributor and a minor modification we made to it to meet our needs better.

Victron Lynx Distributor

Figure 1 illustrates the schematic of our proposed system with a 12 V battery bank.

Figure 1 illustrates the schematic of our power center design using a 12 V battery bank. Our 24 V design is very similar, and the differences are irrelevant to our present discussion regarding the Lynx Distributor shown in the lower center of the figure.

Victron describes the Lynx Distributor as “A modular DC busbar, with locations for four DC fuses. It will monitor the status of each fuse, and indicate its condition with a LED on the front”. The Lynx Distributor is one of four Victron components for power distribution:

  • Lynx Smart BMS
  • Lynx Distributor
  • Lynx Shunt VE.Can
  • Lynx Power In

See Victron Energy’s website for a complete description of each component with associated datasheets, manuals, certification, etc.

Figure 2 illustrates the internals of a Lynx Distributor comprising a positive and negative 1000 A busbar, four Mega fuse holders, and some electronics that indicate fuse status.

We’ve chosen to use a Lynx Distributor in place of a couple of independent busbars and fuse holders that would otherwise be required. These items are conveniently packaged in the Lynx Distributor, as shown in Figure 2. The cost of separate components is close to the price of the Lynx Distributor, but using the Lynx Distributor should result in a clean, professional-looking result.

Our schematic diagram shows that the Lynx Distributor connects to the battery bank via the disconnect switch and SmartShunt. The Lynx Distributor then distributes power to our inverter/charger, our solar charge controller, and the RV 12 V systems or, in the case of our 24 V design, to a 24 V to 12 V DC to DC converter. Mega fuses, housed within the Lynx Distributor, will protect the wiring between the Lynx Distributor and each of the connected loads.

The Lynx DIstributor can report fuse status via its front panel LEDs if it is connected to a Lynx Smart BMS or a Lynx Shunt VE.Can. We don’t have either of these devices planned for our system. The following section describes how we provided power to the Lynx Distributor circuit board to enable the fuse monitoring feature.

Lynx Distributor Hack

Nate Yarbrough produced a great video describing this hack to enable the lights on the front of a Lynx Distributor without having a Lynx Smart BMS or a Lynx Shunt VE.Can in your system. Victron expects this feature to be enabled by connecting the Lynx Distributor to these other devices with the included cable terminated with RJ-11 jacks. However, the Victron manual for the Lynx Distributor indicates which two of the four lines in the RJ-11 terminated wire are needed to power the device. Victron indicates that the device needs 5 V on pin 1, the yellow wire, and ground on pin 4, the black wire. So the task at hand is to generate 5 V from our available source of either 12 V or 24 V and provide it via an RJ-11 connector.

Fortunately, Victron supplies a cable terminated on both ends with an RJ-11 connector. We cut this cable roughly in half, stripped back the outer covering, cut off the two unneeded wires, and stripped the remaining yellow and black wire in preparation for their connection to a 5 V source.

Figure 3 illustrates the small wiring harness, including M8 lugs, an RJ-11 connector, and a 24 V to 5 V regulator.

We chose to use a tiny 24 V to 5 V step-down regulator, available here. Four of these devices were approximately $12. They come with wires and connectors attached and covered with heat shrink tubing. It was a simple matter to connect the outputs of this device to the RJ-11 wires and the inputs to two M8 wire lugs, see Figure 3. We then inserted the RJ-11 plug into the Lynx DIstributor and bolted the wire lugs to the busbars where additional Lynx devices could be attached, see Figure 4.

These devices were advertised as 24 V ready, but we wanted to ensure they would handle the voltages in our eventual system. We tested them briefly by applying a voltage source to the Lynx Distributor busbars ranging from approximately 6 V to 30 V. The LEDs continued to function over this entire range. We don’t expect our Lynx Distributor to see voltages outside of this range. If your design operates at 36 V or 48 V, you will need to find an alternative voltage regulator.

Many techniques, devices, and components could be used to accomplish this modification. However, our approach was straightforward. For convenience, we have included a list of the items that we used:

Summary

We will use the Victron Lynx Distributor in our power center to yield the functionality of two 1000 A busbars and four Mega fuse holders in an attractive and safe form factor. We discussed a modification to the Lynx Distributor so we can take advantage of the fuse monitoring capability. Finally, we pointed out a few of the devices we used for this project that we have found helpful many times.

Students First

At Utah Valley University (UVU), we continue to develop a culture where we focus our efforts on students. UVU is an integrated university and community college that educates every student for success in work and life through excellence in engaged teaching, services, and scholarship. This post addresses how a service organization like the UVU Division of Digital Transformation (Dx) can participate in engaged teaching.

Engaged Teaching

The UVU Office of Engaged Learning describes engaged teaching as the teaching, learning, and scholarship that engages faculty, students, and community in mutually beneficial and respectful collaboration. Consider the three possible pairings of students and faculty, community and faculty, and students and community.

First, students learn from faculty, but faculty, in turn, learn from students. In addition, students help faculty develop their scholarship. Second, our community advises our faculty and gives their scholarship direction. Likewise, our faculty develop scholarship that benefits our community and local economy. Finally, our community provides mentoring, internships, scholarships, and jobs for our students and graduates, and our students provide our community with knowledge, energy, and fresh perspectives.

Our On-Campus Community

Dx at UVU is like information technology organizations at other universities in that Dx provides information technology infrastructure such as networks, servers, storage, telephony, identity, cybersecurity, and more. In addition, Dx includes enterprise architecture, product portfolio management, process improvement services, classroom technology, teaching technology, mobile computing platforms, teaching studios, and more.

Dx provides these products and services through the work of full-time, part-time, and some student employees. In addition to their “day jobs,” some of these employees teach as adjunct faculty in various academic units on campus. In this role, they contribute to engaged teaching as described above.

However, a campus service organization like Dx can more fully participate in engaged teaching as members of the broader community. In other words, Dx should serve as advisors to our faculty and give their academic scholarship real-world experience, data, and direction. Likewise, Dx should benefit from the faculty scholarship that informs our work. Dx should provide mentoring, internships, scholarships, and jobs for our students and graduates. In turn, these students will provide Dx with new knowledge, energy, and fresh perspectives. This insight from students regarding the student experience with the services provided is invaluable and will no doubt improve provided services.

Moving Forward

So, what needs to be done to transform Dx? Well, there are several necessary tasks, approaches, and ideas:

  • When Dx hires new full-time employees, new employees must have the ability and desire to mentor students above and beyond the traditionally required skills.
  • When full-time positions become available, Dx must consider filling the positions with multiple student employees. While student employee turnover is rapid, requiring a tremendous amount of training, isn’t that why we’re hereā€”to educate students who take what we teach them and become productive contributors to society?
  • Dx should provide internships to UVU students.
  • Dx should provide meaningful capstone projects to student groups that will benefit them; in turn, the campus community will benefit from project outcomes.
  • Dx must seek out faculty who teach classes and perform scholarly work that may benefit from the real-world experiences and data that Dx has. Dx must make these experiences and data readily available.
  • When Dx faces questions about technology choices, function, or performance, they should seek out the technical expertise of our faculty colleagues
  • Finally, Dx must find ways to give directly to faculty and students. Perhaps Dx can fund named scholarships for students or fund endowed chairs for faculty. Both endeavors send a clear message that Dx is aware and engaged in the mission of the university

Summary

Digital transformation is about much more than technology and its use; it’s about changing thinking, process, and culture. It is time that Dx and other campus service organizations transform to benefit our students more directly. Employees of Dx and all campus entities should become teachers, mentors, and examples to the students who come to us to learn and grow. We have an excellent opportunity to influence the world for good. Join me in this grand pursuit!

RV Power Center: Physical Space, Wiring, and Solar Upgrade

This post is the fourth of an ongoing series of articles documenting and describing our RV electrical upgrade. In our previous post, we described our battery bank design and discussed where we would place it. In this post, we describe creating the physical space for our power center, our initial wiring, and our solar upgrades.

Power Center Space

Figure 1, This is a 3D model of the pass-through storage space we intend to use to house our power center.

To house our chosen electrical components, we need to build a space similar to what we previously presented. Our proposed power center is illustrated in Figure 1. Component placement will likely change as we deal with surprises and take advantage of opportunities. However, the basic structure seems sound, and the creation of this space will allow progress.

Figure 2 illustrates the physical space we’re starting with and some essential tools, Dewalt impact drill and a Diet Coke. First, we constructed a 3/4″ plywood wall that stretches from the bottom to the top of this compartment and lies flush against the short wall near the top.

Figure 2, This is the space we’re using for our power center. In this picture, we have already run some wires that we’ll describe in the next section.

This approach required a cleat, see Figure 3, attached to the floor to support the plywood wall. To determine the location of the cleat, we held a small piece of plywood against the upper wall and marked the bottom of the compartment with blue tape where it landed when square.

Figure 3, This figure illustrates the lower cleat to support the plywood wall.

The cleat, made of 1-1/4″ by 1-1/4″ lumber, was built by drilling screw holes and countersinking them to allow some 1-1/4″ screws to reach well within the 5/8″ flooring. We also had to add a top cleat, made of the same material, on the right-hand side of this space. The upper cleat was attached to the rectangular aluminum framing using 1-1/4″ self-drilling screws. Finally, before the plywood wall went up, we needed to run a few electrical wires and rescue the Diet Coke.

Initial Wiring

As mentioned in a previous post, our RV is a 2016 Outdoor RV Blackstone 240 RKSB. The floorplan of this model is illustrated in Figure 4. Our new power center will be located in the left-hand side of the pass-through storage area in the upper right-hand corner of Figure 4. Our shore power outlet is located at the left rear of the trailer, while our circuit breaker panel is located just under the refrigerator in the lower left of the figure.

Figure 4, This is the layout of our RV, a 2016 ORV 240 RKSB.

120 Volt AC Wiring

The shore power electrical outlet is wired directly to the circuit breaker panel. However, in our design, the shore power connector must be wired to the inverter/charger, and then the inverter/charger is wired to the circuit breaker panel. We ran Southwire 6/3 Romex from the circuit breaker panel area to the power center to accommodate this need. This line will carry the 50 A shore power to the inverter/charger. We then ran a second piece of 6/3 Romex from the power center back to the circuit panel area. This wire will carry inverter/charger output to the circuit breaker panel to energize our appliances.

Many discussions in RV forums berate Romex because it shouldn’t be used in high vibration environments like RVs and boats. However, Southwire Romex larger than 10 AWG uses stranded wire for three conductors and a solid ground wire. Therefore, we used Romex instead of running a PVC conduit and pulling eight strands of 6 AWG THHN wire through it.

We intended to run this wire ourselves, but it was a task I was not looking forward to. However, our local RV center, where we purchased our trailer several years ago, was willing to run the Romex for a few hundred dollars. That was a deal we couldn’t pass up. They ran the wire neatly and securely and left extra wire coiled behind the circuit breaker panel and in our power center.

Solar PV Wiring

The original solar setup on our trailer was a single 150 W panel on the roof. The installer fed the PV cables through the roof and into an upper cabinet in the bedroom. An inexpensive PWM solar charge controller was installed in that cabinet and then wired down through the trailer cap to the a-frame-mounted batteries.

Soon after purchasing the trailer, we upgraded this setup by replacing the single 150 W panel with three 200 W panels and the PWM controller with an MPPT controller. This upgrade used the existing wiring, and the new controller remained in the bedroom closet. This work aims to improve all aspects of our solar setup and get the solar charge controller out of our cupboard.

We ran new 10 AWG PV cables from the roof through the portal and into the trailer attic near the front of the trailer. Next, we routed the PV cables behind the trailer cap and into our power center. Unfortunately, we purchased 20′ lines with MC4 connectors on each end. We intended to cut the connectors off of one end and fish the cable to its destination. However, we inadvertently cut off the wrong connectors and ended up having to install our own. We should have purchased cable and installed MC4 connectors after they were in place.

Battery and House Wiring

Eventually, as described in our previous post, we will move our battery bank and will need to provide 12 V from our power center to the rest of our trailer. For now, the batteries remain on the a-frame and feed the rest of the trailer from there. Therefore, we need to tap into the existing 12 V and ground line so our new solar charge controller can charge the batteries. Our completed project will eliminate the lines to the batteries.

Figure 6, Power and ground distribution travel through this space from the battery bank to the trailer.

On the underside of the subfloor near the a-frame of our trailer, we found several auto reset circuit breakers. The breaker illustrated in Figure 6 has a direct connection to the positive terminal of our batteries. The positive terminal of our batteries and the trailer emergency brake are attached to the shown stud. We attached a 6 AWG THHN wire with a lug to that terminal and fished the wire into our power center.

Figure 7, We used a Morris connector to connect a ground wire from the existing ground to our power center.

A ground wire also travels through this area from the negative terminal of our batteries and into the trailer. We obtained ground by cutting the ground wire that travels through this space and connected both ends and a new 6 AWG THHN wire with a 3 position Morris connector, illustrated in Figure 7. These connectors are amazing and easy to use. Finally, we fished the new ground wire into our power center.

After the 120 V AC, solar PV, and 12 V DC wiring were complete, we installed the plywood walls. With this done, the power center is ready for the addition of components. The empty power center can be seen in Figure 8.

Figure 8, The empty power center is illustrated with 120 V AC, 12 V DC, and solar PV wiring in place.

Solar Additions

On the roof of our trailer, we installed a fourth 200 W solar panel, as illustrated in Figure 9. We couldn’t obtain another panel identical to the three we had, so we chose a panel with similar voltage characteristics and a current capability that slightly surpassed our existing panels. This panel will not constrain our system or be significantly limited by our existing panels; it should be a good match.

Figure 9, A fourth 200 W solar panel was added to the roof and connected in series to the existing panels.

Before celebrating the installation of our new panel or our wire routing prowess, we measured a voltage of 60 V across the PV cables. The addition of the fourth panel increased the PV voltage to approximately 80 V; success!

We connected the PV cables to a disconnect switch/circuit breaker mounted in a DIN breaker box in our power center. Next, we used a couple of short lengths of PV cable to run from the breaker box to our Victron SmartSolar 150-45 solar charge controller. Finally, we connected our 12 V DC lines to the solar charger, and we’re back in business. Figure 10 illustrates the result.

Figure 10, The completed power center with solar charge controller and PV disconnect switch installed.

The End Result

We’ve reached the end of another sub-project, and the trailer is once again ready to be used. We successfully created our power center space prepared to receive additional components. In addition, we routed all necessary power cables to this new space. Finally, we added a solar panel and upgraded our MPPT solar charge controller.

RV Power Center: Battery Bank Space

This is the third post of an ongoing series of articles documenting and describing our significant RV electrical upgrade. In our previous post, we discussed a potential need for an alternative design and presented its schematic. We also discussed a 3D model of our finished product, and we shared our results. In this post, we describe our battery bank design, discuss where we intend to place it, and the details of making space for it.

Battery Bank Design

Our first article of this series discussed our requirement for a 400 Ah battery bank to meet our electrical needs. However, our 400 Ah requirement assumed a 12 V system. We have since determined that we’d like to implement a 24 V system that reduces our Ah requirement. To enhance clarity, we should discuss our needs in terms of Watt-hours (Wh). A 12 V system capable of delivering 400 Ah is a 4,800 Wh system. A 4,800 Wh 24 V system delivers 200 Ah. We need a battery bank design for both a 12 V and a 24 V system until we determine whether or not Victron will produce a 24 V version of their MultiPlus-II 2x 120V inverter/charger.

Whether we implement a 24 V or 12 V system, we intend to use four Lion Energy UT 1200 lithium-ion batteries to implement our battery bank. We would use their newer UT 1300 batteries, but we already own two of the UT 1200s and found two used UT 1200s for less than half the price of new units. The UT 1200s are rated at 1,152 Wh, while the UT 1300s are rated at 1,344 Wh. So while our goal was 4,800 Wh, we’ll settle for the 4,608 delivered by our four UT 1200s.

24 Volt Battery Bank

We will connect two UT 1200 batteries in series to create a 24 V set. This set can deliver 2,304 Wh, which is well below our goal. Two of these sets can be connected in parallel to yield our desired 24 V battery bank, providing 4,608 Wh. Figure 1 illustrates this configuration. This implementation also adds redundancy in case a battery fails while in the field.

Figure 1, This is a 24 V series-parallel battery bank configuration built using four 12 V Lion Energy UT 1200 batteries. The fuse holder on the left of the figure will hold a 300 A Class T fuse.

Because wire resistance is nonnegligible in these types of systems, it is essential that the circuit length from the positive terminal of any battery, through the load, and back to the negative terminal of the same battery be equal for all batteries in the bank. In practice, this means that the connecting wires between batteries should be of equal length, and the positive and negative connections to the load should be from opposite ends of the battery bank. For example, Figure 1 shows that the positive connection comes from the upper bank, while the negative connection comes from the lower bank.

According to a comprehensive document published by Victron Energy called Wiring Unlimited, an alternative configuration includes a connection between the midpoints of both sets. This configuration is illustrated in Figure 2.

Figure 2, This is a 24 V series-parallel battery bank configuration built using four 12 V Lion Energy UT 1200 batteries and includes a midpoint connection. The fuse holder on the left of the figure will hold a 300 A Class T fuse.

According to the Wiring Unlimited document, this approach requires midpoint monitoring to detect deviations in voltage between the upper and lower batteries. In addition, when deviations are detected and reported, they must be acted on to deal with potential issues. Batteries in the battery bank may be damaged if reported problems are not resolved. Monitoring the midpoint has the advantage of detecting these issues that might otherwise go unnoticed. The Victron SmartShunt, which we intend to use in our system, can monitor midpoint voltages and raise alarms when problems arise.

12 Volt Battery Bank

Alternatively, four UT 1200 batteries can be connected in parallel to yield a 12 V battery bank, delivering the same 4,608 Wh. This configuration also adds more redundancy in case a battery fails while in the field. The obvious configuration to accomplish this is shown in Figure 3.

Figure 3, This is a 12 V parallel battery bank configuration built using four 12 V Lion Energy UT 1200 batteries. The fuse holder on the left of the figure will hold a 400 A Class T fuse.

Notice in Figure 3 that the positive connection comes from the upper left battery in the bank, and the negative connection comes from the upper right or the last battery in the bank.

In a 12 V system, the currents are double those of a 24 V system. These higher currents demand a 400 A Class T fuse and wire with double the cross-sectional area of wire used in a similar 24 V system.

A cleaner wiring layout that still respects the principle of keeping circuit lengths equivalent is illustrated in Figure 4.

Figure 4, This is a 12 V parallel battery bank configuration built using four 12 V Lion Energy UT 1200 batteries. This layout uses the halfway approach of keeping circuit lengths equivalent. The fuse holder on the left of the figure will hold a 400 A Class T fuse.

In the hopes of reducing system currents, voltage drops, and associated ripple, we desire to create a 24 V system. However, if this is impossible due to the lack of availability of an appropriate inverter/charger, the 12 V layout, illustrated in Figure 4, will be used.

Battery Bank Placement

Our RV is a 2016 Outdoor RV Blackstone 240 RKSB. The floorplan of this model is illustrated in Figure 5. Our new Power Center will be located in the left-hand side of the pass-through storage area that is accessed by an exterior door located in the upper right-hand corner of Figure 5. Batteries should be located as close as possible to their associated invert/charger to reduce voltage drops that may occur over long cables. To keep the cables short but still leave storage areas available for their intended purpose, our battery bank will be located under the foot of the bed.

Figure 5, This is the layout of our RV, a 2016 ORV 240 RKSB.

In our last post, we determined that space between the drawers was available for our battery bank. This open space was found during our modeling efforts and is illustrated in Figure 6.

Figure 6, The space between the drawers is sufficient for four Lion Energy UT 1200 batteries.

The UT 1200 batteries measure 10.2″ long, 8.8″ tall, and 6.6″ wide. We started demolition to determine the best way to orient these batteries within the available space. We knew from our previous inspections that two cross beams were holding up the false floor of the storage area above the drawers. We removed the drawers and, using a jigsaw, removed the portion of the false floor between the beams. This roughed-out hole and the exposed space are shown in Figure 7.

Figure 7, This is the rough cut opening that exposed the space we intend to use for our battery bank.

While the drawers are only 17″ from front to back, the glides they’re on are 18″ long. The distance between the backs of one set of glides and the other is insufficient for two side-by-side batteries to sit between them. Unfortunately, 17″ drawer glides are unavailable, and the next size down is 16″.

The lack of space necessitated converting one of our drawers to 16″ glides and adjusting the drawer to match. After removing the glide supports and drawer glides, we constructed a new and more robust support structure shown in Figure 8.

Figure 8, This is the drawer space with a new support structure and drawer glides in place.

We acquired and installed new 16″ drawer glides. In addition, we disassembled the associated drawer, cut 1″ off the sides and bottom, and reassembled it better than new.

The remaining space between the backs of both drawers is now more than sufficient to hold two UT 1200’s side by side. The distance from right to left in Figure 8 is also more than enough to hold two UT 1200s longwise. There is also enough space for the fuse holder that needs to be located near the battery bank.

Figure 9 shows the battery bank space with two UT 1200s in place between the installed cleats.

To assist in holding the batteries firmly in place, we added two cleats to the floor spaced to allow the batteries to sit side by side with little to no room to spare. The cleats and batteries can be seen in Figure 9. Also, notice in Figure 9 that the roughed-out access hole has been cleaned up using a round-over bit in our router, some chisel work, and a bit of sanding.

To restore the utility of the storage space used to provide access to the batteries, we drilled finger holes in the remaining false floor. We also added another false bottom over the top of what can be seen in Figure 9. This can be seen in Figures 10 and 11.

Figure 10, Finger holes were added to the existing false floor to facilitate the removal of the new false floor.
Figure 11 shows that the new false floor restores the storage area while protecting the hidden battery bank.

The End Result

In the spirit of making incremental progress and leaving the trailer functional for camping, we’ve reached the end of this sub-project. We successfully created an excellent space for our battery bank that will work for either a 24 V or a 12 V system. The only negative impact of this sub-project was one drawer is now an inch shorter. In future posts, we’ll install the batteries, wire them together, create a small shelf for the fuse holder, and wire the battery bank to the battery disconnect switch and the SmartShunt.

RV Power Center: Design

This article is the second of an ongoing series of posts documenting and describing our significant RV electrical upgrade. In our previous post, we outlined our requirements and created a schematic of a system that would meet our needs. We also discussed our desire to do the work incrementally, leaving the trailer in working order after each sub-project. Finally, we discussed our desire to build a 24 V system. In this post, we discuss a potential need for an alternative design and present its schematic. We also discuss the need to model our finished product, and we share our results.

Alternative Design

While we desire to build a 24 V system to reduce currents, Victron Energy does not currently produce a 24 V version of their MultiPlus-II 3000 VA 2x 120 V inverter/charger. However, we are hoping they announce such a device at the METS 2021 conference.

Figure 1 illustrates a schematic for a 12 V system that meets our requirements.

In case a suitable product does not become available, we have designed an alternative 12 V system. This version would not need a 24-12 V DC-DC converter, but increased system currents require larger wires to connect the battery bank to the inverter/charger. Figure 1 illustrates the schematic for our alternative design.

Modeling the System

Our desire to make incremental progress without wasting time or money requires us to see the outcome before taking our first steps. If we don’t know where each component will go and how it will be oriented, we will likely make mistakes that waste resources.

To visualize our project, we used Autodesk’s Fusion 360 3D modeling software to create a model of our RV’s pass-through storage space, our under-bed storage area, and the significant components of our system. Then, by placing the scale versions of the desired components into the modeled spaces, we can arrange and rearrange them to ensure the best overall final implementation. We can then undertake small projects without worrying about them negatively impacting future work. We can also simultaneously work on multiple projects that don’t interfere with one another.

RV Storage Spaces

We initially thought we would put both the power center components and the battery bank in the pass-through storage area. However, we decided to place the battery bank in the under-bed storage to reduce the temperature extremes it would otherwise experience.

Figure 2, The pass-through storage area, under the bed drawers, and storage space beneath the foot of the bed. Immediately above these modeled objects is where the mattress sits within the trailer.
Figure 3, The pass-through storage area is on the left, and the under-bed storage space is on the right.

Figure 2 illustrates the pass-through and under-bed storage areas of our trailer. It might be helpful to note that the mattress sits immediately on top of these modeled objects. The under-bed storage comprises two drawers, and immediately above them, a small storage space accessible by lifting the foot of the bed. The area illustrated in Figure 3 seemed to be an ideal place for our battery bank.

Figure 4, The space between the drawers is sufficient for four Lion Energy UT 1200 batteries.

However, we discovered some completely wasted space between the two drawers during our modeling efforts, see Figure 4. This space is almost large enough for four Lion Energy UT 1200 batteries. Some modifications will be necessary, but using this space will leave both the under-bed and pass-through storage areas free for their intended purposes.

This example points out the sound practice of measuring things out and opening up places in your RV to determine what is there and what’s available. You never know when you may need a bit of space for one thing or another.

Modeled Components

Modeling the trailer spaces gave us a great reason to learn a bit about Fusion 360. While we aren’t experts, we learned enough to model each of the major components we’ll use in our system. These models are not precise, but their overall dimensions and appearance are accurate enough for our purposes.

Victron MultiPlus-II 2x 120V
Victron SmartSolar MPPT 150/45
Victron SmartShunt
Victron Lynx Distributor
Victron Cerbo GX
Victron Orion DC-DC Converter 70A
PV Circuit Breaker Box
Lion Energy UT 1200 Battery
Blue Sea Class T Fuse Holder
Blue Sea 300 A Battery Disconnect Switch

This modeling effort enabled us to place each component, move them around, ensure adequate spacing, etc. The implementation illustrated in Figures 5 and 6 was achieved by adding a wall in our pass-through storage space and placing the modeled components. As previously mentioned, we may have to implement a 12 V alternative by removing the DC-DC converter and adjusting fuse values appropriately.

Figure 5, This is the front view of the RV Power Center showing the layout of all major components. The solar charge controller and PV breaker are in the upper left. The DC-DC converter is in the lower left. The inverter/charger is in the center of the figure, while on the right side, we have from top to bottom the Cerbo GX monitoring system, the SmartShunt, battery disconnect switch, and the Lynx Distributor.
Figure 6, This top view of the RV Power Center component layout demonstrates sufficient clearance from all devices, walls, doors, etc.
Figure 7, The four batteries fit nicely between the drawers with the 300 A Class T fuse nearby.

As previously mentioned, the battery bank will be located between the drawers in the under-bed storage area. In addition, we’ll build a small shelf near the batteries where our 300 A Class T fuse will be located. The battery cables will pass through the thin wall between the under-bed area and the pass-through storage area and then travel down to the left in Figure 7 until they reach the battery switch and SmartShunt.

Summary

In this post, we discussed our alternative 12 V design and modeled the physical spaces and components in the hope that we get it all right the first time around. This may be an optimistic goal, but having this detailed plan in hand will enable small projects to fit more seamlessly together. Now the work begins.

RV Electrical Upgrade

We spent more than 30 years tent camping and backpacking with our children, but recently we’ve transitioned to a bumper pull RV. We continue to love camping in the great outdoors but like to do so with all of the luxuries of life, glamping. We love the solitude and the noises of nature and tolerate crowded campgrounds and the noise of generators that start each morning and run through the day. Instead, we want to take a different path. We want the best of both worlds, and this series of posts will document our path that leads there.

The Big Picture

We want the ability to use our microwave, television, and other 120 V AC systems without having to ruin our camping solitude with a generator. In addition, we want to minimize the intrusion of our generator while recharging our batteries.

On a typical day of camping in our RV, we consume 1400 Watt-hours or approximately 115 Ah of our 12 V system. About 30 Ah are consumed watching television for a few hours and 85 Ah for lights, fans, heater blower, etc. We want to watch TV for several hours per day and use a game console for several additional hours. In addition, we want to use our microwave for making snacks along the way.

Using our TV for six hours consumes 60 Ah, three hours of our game console consumes 30 Ah, and our microwave for 10 minutes consumes 13 Ah, totaling 103 Ah. This usage, combined with the 85 Ah mentioned above, brings the total to nearly 200 Ah. To ensure some reserve power, we’re planning on a 400 Ah battery bank. To recharge our batteries each day, without having to hear that noisy generator, we’re planning on 800 Watts of solar.

To accommodate our AC devices, including the TV, game console, and microwave, we need an inverter/charger capable of producing 1320 Watts or more. We’d also like to use our air conditioner for short periods to keep our dog comfortable while we shop, eat in a restaurant, take a short hike, etc. Our air conditioner consumes approximately 1500 Watts. We also desire the charger to charge our battery bank as quickly as possible for those terrible days when we have to run our generator. Our RV is wired for a 50 A service, and this should be passed through to the circuit panel when connected to shore power.

In summary, we want to enjoy the quiet solitude of camping and some of the luxuries of life. We want to do this with as few detrimental modifications to our trailer as possible. Several items will make this goal a reality:

  • 400 Ah of lithium-ion batteries
  • 800 Watts of solar power
  • An inverter that is capable of producing nearly 3000 Watts of 120 V AC power
  • A battery charger that is capable of consuming our entire generator output to minimize charge time

Our Plan

We intend to accomplish our previously outlined goals incrementally so that between projects, our trailer is still functional. Therefore, our first step was to develop our design so we could start breaking it into sub-projects. Figure 1 is the schematic of the plan we intend to implement.

We made an early design choice to create a 24 V system with four 12 V lithium-ion batteries. We chose this because the components we intend to use work at 12 or 24 V, and at 24 V, the system currents will be cut in half, reducing wire size and decreasing unwanted heat dissipation.

Figure 1, Schematic diagram of 24 Volt electrical system with 12 Volts available for backward compatibility with existing RV systems.

We intend to locate most of the equipment illustrated in Figure 1 in the left-hand side of our pass-through storage area near the front of our trailer. We’re going to call this location our power center. The solar panels will go on the RV roof, and the batteries are going under our bed which is just to the rear of the pass-through storage area.

Currently, our trailer is configured in a fairly standard way. We have two Lion Energy UT 1200 lithium-ion batteries mounted on the front a-frame of our trailer and housed in conventional plastic battery boxes. We have some solar on the roof with the solar charge controller mounted in a bedroom closet, and the rest of the electrical components and wiring are factory default. Our upgrade project will require a lot of time and work, and as previously mentioned, we intend to do it incrementally and leave our trailer in shape for traveling between sub-projects. Our tasks include:

  • Constructing the new power center with sufficient space and strength to mount all of the components in our design.
  • Adding solar panels, routing PV cables to our new power center, mounting our charge controller and disconnect switch, and connecting to our original battery bank.
  • Making room for our four batteries under our bed.
  • Connecting the batteries in a parallel/series configuration to obtain our desired 24 Volt system and interfacing this new battery bank to the existing RV systems.
  • Routing AC lines from the power center to the existing RC circuit panel and back.
  • Mounting the remaining components in the power center and wiring them into the system.
  • Configuring each prgrammable component.
  • Thoroughly testing the system, cleaning up flaws, and enjoying the outcome

This post is the first in a series to document our journey from where we are to where we want to be. Each sub-project above will be thoroughly described in separate posts, and we’ll include the good, the bad, and the ugly. We hope you enjoy our journey.

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