Dean and Mary

Yes, this is the easiest way to implement that option, in my opinion, at least until someone comes up with a better approach. You've definitely got my wheels turning again. I had pretty much settled on the manual switch route, but after reading the discussion and thinking through the pros and cons, I may still end up going with the hardwired Engine ON detection option after all. I need to stop talking about it and get out there and run some wires. Seriously, the more I discuss a project, the less likely I am to have to do it twice. I've learned that spending time planning and bouncing ideas off others is usually much cheaper than discovering a better way after everything is already installed.

I agree and had intended to mention that earlier. With the hardwired Engine ON detection option, there is no need to spend time fine-tuning the voltage parameters. I considered going that route, but my plan is to leave that feature disabled and instead wire the Orion through a manually operated switch that is easy to access. That will allow me to disconnect the charger whenever needed. There is little benefit to having the Orion enabled while boondocking for a week, even though it is disconnected from the tow vehicle. The manual switch would also provide an additional layer of protection against battery discharge when stopping for the night and not disconnect the trailer from the TV. I also plan to connect the cooling fan from Mobile Solar Consulting for the 50-amp Orion charger to the same double-pole switch. That way, both the charger and cooling fan can be enabled or disabled together with a single switch.

John, what a detailed and accurate summary. Thank you for taking the time to lay it all out so clearly. The recent introduction of the 70-amp Orion XS adds another layer of complexity for installers. It provides even more charging capability, but it also raises additional questions regarding wire sizing, voltage drop, fuse selection, alternator capacity, heat management, and overall system design. What was already a somewhat confusing topic for many owners with the 30-amp version has become even more complicated with another high-output option now available. Fortunately, I believe 50 amps of charging while driving is all I will ever need, and I'd prefer not to be pushed into upgrading the alternator. Depending on how things perform in real-world use, I may end up using the Orion's settings to limit the current draw on my 50 amp to a lower value.

Carpenter, I just saw your post. I agree, I wouldn't want to store gasoline or a generator inside the truck topper either. I want to check with my better half before committing, but we may be willing to part with our front aluminum tray. Since we have the Sea Biscuit storage box, I don't see us switching back. Send me a message and we can work out the details.

I read every word of the article and found it extremely useful, especially since I'm currently installing a DC-to-DC charger in my 2019 Ford Lariat with the factory tow package. The information was well presented and made a lot of sense. I'm still using my original 2019 battery and had already planned to replace it this winter. One thing I learned from the article was the need to perform a BMS reset after battery replacement, which was new information to me. A word of caution for anyone reviewing the article and applying the results to their own installation. The voltage drop calculations were based on a 30-amp charger. If you're considering a 50-amp charger, the voltage drop increases significantly compared to the 30-amp charger. This will change the wire size requirements and/or Orion input parameters. See the AI-generated information below for a comparison. (Since I am in the process of my installation, I have decided to use 1/0 AWG for my Orion 50 amp installation.) AI Overview To calculate the exact voltage drop for a 50-foot one-way run pulling 50 amps on a 12-volt system, you must look at the wire size (gauge) being used. Because DC circuits require a complete loop (a power wire and a ground return wire), the total electrical distance is a 100-foot round trip. [1, 2] An acceptable voltage drop for general applications is under 5%, and under 3% for critical or sensitive electronics (like DC-to-DC chargers or lithium batteries). Here is how different copper wire sizes perform under these exact conditions: [1, 2] Wire Gauge (AWG) Voltage Drop (Volts) Voltage Drop (%) Voltage Remaining at Trailer Recommendation 6 AWG 2.46 V 20.46% 9.54 V Unacceptable. Severe voltage drop; equipment will malfunction. 4 AWG 1.54 V 12.83% 10.46 V Poor. Exceeds maximum 10% tolerance for heavy loads. 2 AWG 0.97 V 8.08% 11.03 V Borderline. Acceptable only for highly resilient equipment. 1/0 AWG 0.61 V 5.08% 11.39 V Good. Reaches the industry standard 5% limit for generic loads. 2/0 AWG 0.48 V 4.03% 11.52 V Excellent. Optimal choice to minimize loss over this distance.

Those crimps look substantial! For the project I'm currently working on, I purchased a hydraulic crimping tool from Powerwerx. On previous projects, I used a hammer-style lug crimper, which worked well, but I wanted a more consistent and professional crimp for this installation. I also chose the Anderson SB175 connector instead of the SB125 to provide additional current-handling capacity and a bit more margin for future upgrades. Best of luck, Dean

John, After reading a few of your thousand-plus posts, I've come to realize that you're usually the one providing troubleshooting advice, not asking for it. I mainly wanted to say that I agree a properly functioning 50-amp Orion charger is not overheating the way you have it installed. The real question is what changed between when it was working correctly and when it started behaving differently. I'm sure you'll track down the cause and let everyone know what you find. My guess is that it's a connection-related issue, possibly something as simple as a poor connection between the tow vehicle and the trailer. Are you using an Anderson connector? I have had wires work loose in what I thought was a good crimp on the Anderson lugs. Given your track record, I suspect you'll have it figured out before the rest of us.

Thanks for the update. I'm still waiting on an order that I placed back in July and was planning on given them another call. Your update saved me making a call.

You're welcome. John brought up a good point. Oliver simplified the plumbing by adding a valve, which allowed them to reduce the number of inlets.

all fiberglass travel trailer

Geoff, Thanks for the detailed feedback. I agree with everything you mentioned in your response. Four-gauge cable is commonly used, even though the voltage-drop calculations and cable-sizing tables show that the loss can be higher than ideal for maximizing the efficiency of the Orion XS. I think a lot of the recommendations stem from camper van installations where the cable runs are much shorter, as you suggested. Victron generally recommends keeping DC voltage drop below 2.5% to achieve optimal charging performance and efficiency. When I run the numbers, review the voltage-drop tables, or even check with AI tools, the results consistently point to 1/0 cable as the size needed to stay within that guideline for a typical tow vehicle-to-trailer cable run of 80 feet round trip. Based on that, it looks like my Orion installation is going to cost more than I originally anticipated, especially considering the current price of quality copper cable. However, I'd rather size the wiring correctly the first time than leave charging performance on the table. I will install individual terminal lugs a few inches before connecting to the Orion and then connect with 4 gauge wire. Thanks, Dean

While gathering information for this project, I also discovered that Victron has introduced a new Orion XS 12/12-70A model. It has the same footprint and mounting pattern as the 50A version but adds integrated cooling fans. Victron also slightly increased the terminal size, which should make it much easier to terminate 4 AWG wire. Getting 4 AWG wire into the terminals of the 50A version can be a challenge, so that is a welcome improvement for higher-current installations. It is pricey and I just recently purchased my 50 amp version, so not for me at this time.

Accidental duplication.

Thanks, Geoff. I appreciate all the information you've shared. I'm in the process of installing my DC-to-DC charger now, but I haven't begun working on the tow vehicle portion of the project. Your comments about the cabling requirements and the tow vehicle current sensor gave me some useful information to consider before I get started on that part of the install. I agree that the 50A Orion XS is significantly more efficient than the 30A version. Even with the improved efficiency and reduced heat output, I plan to mount my Victron Orion XS 12/12-50A DC-DC charger on top of Mobile Solar Consulting’s Orion Fan Module, which features temperature-controlled cooling. If you’re not familiar with this option, there are several YouTube videos that demonstrate the noticeable reduction in operating temperatures when using the fan module. For me, the added cooling is inexpensive insurance for a component that will often be operating under heavy load. Dean

I hope to be at that point within a year or less.