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.

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.

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