DC to DC troubleshooting

[jd1923]

Hooked up the Orion 50A DC-DC charger today at idle on our property. It created a 30A output, most of the time, which is the good number at idle (40A+ when towing). However, it freaked out twice in the first 30 minutes while I was testing/watching the app on-n-off for about 90 minutes.

Truck running at idle, voltage at the battery AND at the Andersen DC-DC connection at the bumper (while disconnected from the Oliver) were both exactly 13.56V. I'm thinking you need a load to show voltage drop, but I'm just the installer. 🤠

So, I started the hot water heater, on inverter pulling 120A to bring batteries to some lower SOC to pull amps/needing a charge!

The picture below shows the Victron Connect app for the Orion 50, 4 screenshots side-by-side, and note the change in frame #3, all over a 5 minute period of time. I noticed this behavioral pattern twice in just the first 15 minutes. The second time, the Orion went into the OFF (not charging) position, all on its own for just a minute or two.

It's difficult to watch the app and take other readings, but later I had the Klein ammeter, clamped around the 4 AWG B+ at the battery. It read 28.9A with very little variation at all for the 10 minutes I was looking.

BTW re temperature? It was 60F in the cabin. Hand touch on the Orion 50 was barely warmer, not enough heat to warm my hand.

I'm now thinking my connections are fine. I'm going to contact Nations Starters to test the alternator. More likely it's the Victron Orion acting up. I had a Victron 15A MPPT SC fail twice already. More, later...

Edited Friday at 03:35 AM by jd1923

[Snackchaser]

12 hours ago, jd1923 said:

More likely it's the Victron Orion acting up

Jd, from those screen shots, I’m seeing the system working as it should.  Before calling Nations Starters, check the Orion’s settings.  Your screenshots show the input sitting at about 13.1 V, which is exactly the Orion’s default engine shutdown voltage for a smart alternator.  When the input reaches 13.1 V, the Orion cuts its current to hold the voltage there (frame 3), and if it stays below 13.1 V for a minute, then it decides the engine is off and stops charging.  At idle you’re losing about 0.45 V between the truck and the Orion at 30 amps load, which is about right for a long #4 run.  The voltage drop will increase with load.

Try lowering the shutdown voltage to about 12.9 V.  You could also lower the input current limit in 5 amp steps to find a happy spot, but it might also lower the current while towing at higher RPMs.

Anyway, It’s probably not a failing Orion or alternator, just settings that are tight for idle charging.  If you catch the app when the charger shuts off, then you can also check the “Why is the charger off?” message for more clues.

You're on the right track!  Geoff

[Dean and Mary]

13 hours ago, Geronimo John said:

I hope that the attachment brings some understanding of the complex relationships and equipment that makes these not so simple DC/DC charging system so valueble to us "Long Ranger" OTT owners. SO, with a strong beverage of choice in hand, I encourage the technicals and Rabit Hole Society Members to provide correcting inputs.  At some point I will update the attachment and repost…… 

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.

Edited Friday at 04:03 PM by Dean and Mary
Clarification

[jd1923]

3 hours ago, Snackchaser said:

Your screenshots show the input sitting at about 13.1 V, which is exactly the Orion’s default engine shutdown voltage for a smart alternator.

Thanks, Geoff. I'll hook up again soon to check settings and tweak the numbers. Installation was March of 2025 and I just checked my write-up where unfortunately I didn't document anything on the Orion XS configuration.

To learn more about this I just watched a few YouTubes. This one was the most thorough. @Olive2Roam should check this too as there is a Smart Alternator setting and he discusses how they can run very low voltage.

Also discussed in the video is having an ignition wire connection (hot only when key is in ON position) to the switch on the Orion. This might be the perfect fix for a smart alternator so that engine shut-off detection can be turned off. This is hardwire engine ON detection which means running a light gauge ignition wire from TV to TT, having another connection at the rear bumper.

Strange how Bob's setup and mine were running just fine for a year or so and then not. Did Victron notify us and we both uploaded a firmware change that reset settings to factory defaults? It shouldn't do that but I'll soon note my current settings.

 

Edited Friday at 07:33 PM by jd1923

[Geronimo John]

Dean:

Good response above.  Glad you are going with the 50 A version.  Although I stated in several places in my post about the equipment I have for DC/DC charging another reminder to owners to double check numbers and settings for THEIR gear.

3 hours ago, Dean and Mary said:

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.

You chart is a huge eye opener about voltage drop.  

3 hours ago, Dean and Mary said:

To calculate the exact voltage drop for a 50-foot one-way run pulling 50 amps on a 12-volt system

All of the below is based upon a 100' out and back distance.

Looking at the numbers for the older 30 amp vs. the newer 50 amp is great.  But the calculation understates the problem of using too small cables:    

• With use of oversized cables in an ideal world, both units could produce their rated outputs. But in the real world we need to remember there are losses that will be incurred.
• With oversized cables and Orion individual efficiency of operation:  At the TV batteries the 50 amp version input will likely pull just a bit more amps due to its very high efficiency.  But the 30 amp version with it's much lower efficiency will pull a lot more amps at the TV battery.  
• With oversized cables, I'm guessing in the real world, at the TV battery the 50 amp would be pulling about 53 amps. The 30 amp unit would pull 38 amps. 
• To more accurately calculate the wire size one would need to use the estimated 54 amps or 40 amps for the two calculations. 
• When we add in the degrading factor of the 100' actual resistance losses, the Orion units output will be decreases and the input from the TV will be increased.

So what practicle conclusions can we derive from this?  Here are a few that my pea brain is pondering:

• Your great chart is overly kind.  Assuming 100' of cable, very high grade copper wire, and excellent terminations:  The wire size for the 30 Amp output Orion should be 2 AWG (minimum) and 1/0 preferred.   For the 50 Amp output Orion it should be 1/0 (Minimum) and 2/0 preferred.

• That for the negative cable, one should always use an out and back cable design vs using the truck and trailer frames as conductors.  

• That using #4 AWG cabling with a 50 amp Orion is not going to get anywhere close to the rated 50 amp amperage to the TV...... unless the cables are also upgraded.

In my case of my three year installed 30 Amp Orion, 100' of very high grade copper cable #4 cables, with the unit mounted under the fore port seat;   I must remove the cover and cushions AND add supplemental fans under the Orion.  And then I'll likely see the unit stay on, but still only produce a bit over 20 amps contineous.   And that is fine now that I understand why I'm not going to get close to 30 amps.

In summary, the reality of phisics that you, Geoff, and JD have made clear is just what it is.  And I thank each of you for taking the time to help me understand why.  

GJ

 

[Dean and Mary]

5 minutes ago, Geronimo John said:

So what practicle conclusions can we derive from this?  Here are a few that my pea brain is pondering:

• Your great chart is overly kind.  Assuming 100' of cable, very high grade copper wire, and excellent terminations:  The wire size for the 30 Amp output Orion should be 2 AWG (minimum) and 1/0 preferred.   For the 50 Amp output Orion it should be 1/0 (Minimum) and 2/0 preferred.

• That for the negative cable, one should always use an out and back cable design vs using the truck and trailer frames as conductors.  

• That using #4 AWG cabling with a 50 amp Orion is not going to get anywhere close to the rated 50 amp amperage to the TV...... unless the cables are also upgraded.

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.

[Geronimo John]

51 minutes ago, jd1923 said:

Also discussed in the video is having an ignition wire connection (hot only when key is in ON position) to the switch on the Orion. This might be the perfect fix for a smart alternator so that engine shut-off detection can be turned off. This is hardwire engine ON detection which means running a light gauge ignition wire from TV to TT, having another connection at the rear bumper.

JD:

That's one way to get there.  I did not connect mine, but am rethinking it.

Let's consider putting to better use the truck OEM charge battery cable that we all disconnected in the past for the Litho's.  Just enable it to pass back thru the existing 7-wire connection and redirect it to the Orion.   That line is hot only when you need it for this purpose.

GJ

Edited Friday at 08:19 PM by Geronimo John

[Geronimo John]

9 minutes ago, Dean and Mary said:

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

Spot on.

At the time running my #4 cables was costly in time and materials.  The 100' length of cable for a 70 amp unit would be super heavy and off the charts expensive.  I'll be staying with my 30 amp and cables at least until it dies.  Then relook at the actual performance of the 50 amp unit with the same cables.  So GO JD to figure it out for me.  LOL

In the mean time I will be moving my negative wire over to the fender stud, adding my twin spare set of refer fans under my Orion, and resetting the Victron settings per the "Rabbit Hole" attachment.

For any ownere with or considering DC to DC, I think this thread has documented some really sage info to make the process easier and more effective.

GJ

[Dean and Mary]

41 minutes ago, jd1923 said:

Also discussed in the video is having an ignition wire connection (hot only when key is in ON position) to the switch on the Orion. This might be the perfect fix for a smart alternator so that engine shut-off detection can be turned off. This is hardwire engine ON detection which means running a light gauge ignition wire from TV to TT, having another connection at the rear bumper.

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.

[Dean and Mary]

15 minutes ago, Geronimo John said:

Let's consider putting to better use the truck OEM charge battery cable that we all disconnected in the past for the Litho's.  Just enable it to pass back thru the existing 7-wire connection and redirect it to the Orion.   That line is hot only when you need it for this purpose.

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.

[jd1923]

6 hours ago, Snackchaser said:

just settings that are tight for idle charging.

DONE - SOLVED - Yay! I hope Bob gets theirs working asap! So glad I took time to add those screenshots. Geoff read them and had the answer. I understand most of it but it's confusing!

Turns out I had the Engine Shutdown Detection at the default settings (see pic, left frame). I had adjusted the battery charge settings but nothing else. Not sure why it was running better, then not, since looking back at my pics during installation I'm pretty sure now the Orion was always at these defaults.

Taking into consideration what Geoff wrote and the YouTube video, I set mine to Standard Alternator and then when I changed individual voltage settings it's then called User-Defined. The new settings chosen are also pictured (center frame).

She's running better than ever! Before I was getting about 42A when towing. Now I'm getting that at idle. I held the pedal to bring the diesel idle up at 1600 RPM and the Orion moved up to a 46A output.

For some reason (?) the Input Voltage shown on the app is the same number as the selected Shutdown Voltage. It was 13.1V, now 12.8V and I changed it to 12.7V it did the same thing. Then I set it back to 12.8V.

The Klein clamp ammeter showed the same numbers as the app. I measured all three 4 AWG wires at the Orion. I found Input Amps - Output Amps was equal to the approx 4A reading for the Orion Ground Wire. The 4A must be the current the Orion is using in doing the work of the DC-DC charger.

The Orion 50A charger during tests today and yesterday got just slightly warm to the touch. I could leave my hand completely over it for as long as I wanted.

Yes, @Geronimo John and others might want to upgrade to the 50A given your 30A charger is truly getting hot!

[jd1923]

2 hours ago, Dean and Mary said:

There is little benefit to having the Orion enabled while boondocking for a week, even though it is disconnected from the tow vehicle.

I leave all of our Victron products on all the time. I have breakers for everything under the dinette seat, didn't want extra switches. I'm not saying this is the right way.

We also leave our Outside Courtesy Lights on 24x7 (rodent deterrent). Everything on we burn about 1.75A. About 1A for the MP2, 0.25A for the lights and 0.5A for all other electronics ON or on standby. The rooftop solar replenishes this much even on cloudy days.

The last thing you want is to be towing down the highway and think, "oops, I forgot to turn on the Orion!" I've read here about some turning off their LevelMate to save batteries. Same thing, you're backing into a campsite and realize the LevelMate is OFF, bummer.

We have the PRO model hardwired, always ON. I also have our Victron MPPT SC always ON. It's for the suitcase solar that we rarely use but when I plug in the solar cables it wakes up the SC. Am I hurting the SC leaving it on standby? IDK, but ours has been ON for two years now.

Our hull has a power switch for the rear camera. This would be another circuit where just when you need it, it would be OFF! I never used the cameras anyway and have since removed them.

Geoff has posts where he added timers to some of his devices, allowing the time-out to switch power off. Lot's of good solutions and things to think through before the installation.

Edited Friday at 11:20 PM by jd1923

[Geronimo John]

8 hours ago, Dean and Mary said:

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

You are sounding more and more like a  potential canidate for the OTT Rabbit Hole Society!  🙂  I love it....

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

5 hours ago, jd1923 said:

Yes, @Geronimo John and others might want to upgrade to the 50A given your 30A charger is truly getting hot!

For sure when mine dies.  No need to rush into this on my end.  However, I'll be monitoring your wonderful results to make sure that your cables and the 50 amper holds up with the high voltage drop issue still out there.

Bottom line I'm thrilled with the efforts for all of us.  You and Geoff are "Pathfinders" on this topic, and others, for sure!

GJ

[Snackchaser]

My suggestion of using the 12 V wire from the 7-pin tow harness to trigger the Orion through its L input is gaining traction.  But it was only meant as a last resort if changes to the Orion’s settings didn’t correct the problem.  The preferred method is still automatic detection, and it will work best for most installations.

However, if you choose to go down that road, I’ll re-caution that the wire needs careful testing first.  The tow harness 7-pin 12 V wire must be disconnected from the trailer battery, or the battery will back-feed it and hold the Orion on.  The wire must be hot only with the engine running, not with the key off, and not with the key on and the engine off, or it can quickly drain the tow vehicle’s battery.  Also be aware that some vehicles reportedly only energize it when they detect a trailer or a load, and the Orion would be invisible because the input draws almost nothing.  Just be aware that the 12 V tow wire can behave differently across truck brands, models, and years.

If you still want to go that route, then a cleaner option is a separate connector fed from a true engine-running source, such as an oil-pressure switch, an up-fitter engine-on output, or a CAN interface module programmed on engine RPM.

Consider using Anderson’s SBSX-75A sealed connectors.  They connect the power cables and up to 6 additional wires.  They have a waterproof rating, handle up to 140 amps, and they are designed for 5,000 mating cycles.  The new SBSX Pro model was robustly designed for electric riding mowers with battery monitoring.  It has a clean looking panel mounting and 8 aux contacts.

In my case, the 12 V wire is already in use for automatic rear camera switching, and I’ve been noodling a project to use the SBSX PRO to wire a BMS display head in the truck using the Anderson contacts for an RJ12 connection.  That still leaves extra contacts for creative ideas such as a in truck - trailer air conditioning control.  Let's see how fast this idea catches on!

Oh, the Anderson connectors only accept up to #4 wire, so a short pigtail might be needed to connect heavier cable.  This only adds negligible voltage drop.

Either way, it’s worth careful thought before going down the road of tow-wire signaling over the preferred automatic engine on detection.

Hope this helps for better informed decision making.  Cheers!  Geoff

[jd1923]

On 11/6/2026 at 8:51 AM, Dean and Mary said:

I have decided to use 1/0 AWG for my Orion 50 amp installation.

I went with 4 AWG for cost reasons and the fact the Orion 50 terminals take 4 AWG max.

I spent $95 for 65 ft. Today this costs $145. Also today 85 ft of 1/0 costs $354!
https://www.amazon.com/TEMCo-WC0180-50-Welding-Battery-Copper/dp/B00LIB4JP2/?th=1 These prices are generally even higher from other suppliers.

I understand the EE calculations for a 50A load and wire gauge and length considerations. And I truly understand how important this can be in residential, commercial and industrial installations. Voltage drop can be an issue with electronics and some discerning appliances but honestly isn't it a lesser consideration for a battery charger? These DC-DC chargers can accept input voltage from 9V to 17V.

Does it truly matter that an alternator producing 13.8V at the low end (13.8-14.2V is our range) with a 0.5V voltage drop, still delivering 42A at 13.3V?  You lose potential but your not hurting anything given the drop is not causing excessive heat in the charger and wiring.

If you're going to spend $200 more in wire gauge, I strongly suggest you spend ONLY another $67 to upgrade to the Orion XS 70A. With 1/0 wire, after you leave the EE calculations and worries to the side, you'll find in application you'll likely get 60A from the Orion XS 70A. You can always limit the Input Current to any value on any Orion charger model.

https://invertersrus.com/product/ori121221040/

It also has built-in cooling fans for the little extra money, but our 50A barely gets warm at all running on under-sized wire, go figure! 😎

4 hours ago, Snackchaser said:

Oh, the Anderson connectors only accept up to #4 wire, so a short pigtail might be needed to connect heavier cable.  This only adds negligible voltage drop.

Geoff mentioned this first re the Orion terminals and here re the Andersens. Yes, both are 4 AWG. In the Andersen SB175 lug designed for 4 AWG, the opening is actually a little larger, but the Orion has a tight fit with 4 AWG.

Instead of adding pigtail cables, wouldn't it be a simpler the strip the 1/0 wire and then trim the copper strands down in size to fit the terminals? The pigtails adds more cost, more resistance in connections and additional points of failure. I imagine trimming the wire size would not be "to code" but it's the way I would do it for simplicity.

Heat shrink the Andersen poles as I showed above and certainly buy the "environmental boots" (also pictured above). You need two parts, both Source and Load side boots

https://powerwerx.com/anderson-36036p1-sb175-environmental-boot-source
https://powerwerx.com/anderson-36037p1-sb175-environmental-boot-load

Edited 13 hours ago by jd1923

[Geronimo John]

4 hours ago, Snackchaser said:

  The tow harness 7-pin 12 V wire must be disconnected from the trailer battery, or the battery will back-feed it and hold the Orion on

For sure.  But then if we had not disconnect that direct link between our Litho's (when we installed them) at best we would have blown its fuse in the TV.  Or worse. But a good reminder to disconnect that wire as GalwayGal (I think) mentioned this long ago.

Always good to keep Top of Mind the requirement to disconnect the TV charge wire (Usually AWG 12 or smaller) from the TV OEM line. 

Originally, the OEM "Charging Wire" to the 7-Pin Connector was to keep the trailer emergency brake battery "somewhat" charged.  Back then they were TV LA to Trailer LA batteries.  The two batteries would equalize while driving.  With a brakeaway, a ten year totally neglected near dead trailer battery likely would have had enough charge in it to sent 6 or 12 amps (Single axle/Double axle) for the ten seconds or so to lock up the trailer wheels and get the trailer stopped or at least slowed down.  

For most modern RV's, the onboard batteries provide the power for a breakaway event.  And for those trailer with LA, the wire still is a good feature.  Hence it is still provided by the TV OEM's.  But as soon as Litho's in the trailer are involved that line needs to be disabled from the Litho's. 

For reuse in this creative approach, your cautions are very much on target!

 

Edited 13 hours ago by Geronimo John

[Dean and Mary]

On 11/6/2026 at 3:47 PM, jd1923 said:

DONE - SOLVED - Yay! I hope Bob gets theirs working asap! So glad I took time to add those screenshots. Geoff read them and had the answer. I understand most of it but it's confusing!

Turns out I had the Engine Shutdown Detection at the default settings (see pic, left frame). I had adjusted the battery charge settings but nothing else. Not sure why it was running better, then not, since looking back at my pics during installation I'm pretty sure now the Orion was always at these defaults.

Great, that has to be a good feeling. Glad the problem is solved. 

On 11/6/2026 at 4:13 PM, jd1923 said:

I leave all of our Victron products on all the time. I have breakers for everything under the dinette seat

John,

My perspective is still shaped by the 18 years I owned a Bigfoot RB21. Even with a solid solar setup and a healthy battery bank, I never had enough capacity to completely ignore phantom loads and stop keeping an eye on power consumption. With the new system, that should no longer be a concern.

That said, I decided to control it using pin 4 of the 7-pin connector. Based on what I've read in the owner's manual for my 2019 Ford F-150, that approach should work well. It will also power the unit down automatically when appropriate, and startup should be automatic once the tow vehicle detects a trailer and the required conditions are met, such as the driver's door being closed.

I'll share more details once I've completed the installation and had a chance to test everything in real-world use. I appreciate your report on temperature. I will mount mine on the fan produced by Mobil Solar consulting because I need to mount it horizontal. 

I also plan on putting all of my isolation breakers, cutoff switches and misc. switches under the dinette. 

8 hours ago, Snackchaser said:

Oh, the Anderson connectors only accept up to #4 wire, so a short pigtail might be needed to connect heavier cable.  This only adds negligible voltage drop.

The Anderson SB175 supports cable contacts up to 1/0 AWG, while the SB120 is limited to contacts for up to 2 AWG cable, according to the Powerwerx specifications. Since I am running 1/0 cable, I ordered the SB175 along with the matching 1/0 cable contacts. 

 

8 hours ago, Snackchaser said:

However, if you choose to go down that road, I’ll re-caution that the wire needs careful testing first.

I completely agree with this sound advice. Thank you for taking the time to outline the pros and cons of the different approaches. Those considerations are important and will help others determine which option best fits their particular setup and needs.  Each tow vehicle will be different. I will soon test my F-150 to determine if what I read is correct and post the results. 

[Dean and Mary]

4 hours ago, jd1923 said:

I understand the EE calculations for a 50A load and wire gauge and length considerations. And I truly understand how important this can be in residential, commercial and industrial installations. Voltage drop can be an issue with electronics and some discerning appliances but honestly isn't it a lesser consideration for a battery charger? These DC-DC chargers can accept input voltage from 9V to 17V.

Does it truly matter that an alternator producing 13.8V at the low end (13.8-14.2V is our range) with a 0.5V voltage drop, still delivering 42A at 13.3V?  You lose potential but your not hurting anything given the drop is not causing excessive heat in the charger and wiring.

If you're going to spend $200 more in wire gauge, I strongly suggest you spend ONLY another $67 to upgrade to the Orion XS 70A. With 1/0 wire, after you leave the EE calculations and worries to the side, you'll find in application you'll likely get 60A from the Orion XS 70A. You can always limit the Input Current to any value on any Orion charger model.

John,

I completely agree with what you're saying, and I've given this a great deal of thought. The one area where I might differ is on the voltage drop. The tables I'm using show a voltage drop closer to 1.23 volts on an 80-foot round-trip run of 4 gauge wire.

That said, the Victron manual specifies an input voltage range of 9-17 volts, meaning the charger can still produce a charging voltage for the trailer batteries even with an input as low as 9 volts. The manual also lists a maximum cable cross-section of 4 AWG, which I assume is more of a terminal-size limitation than a recommendation for optimal system efficiency.

I also place value on real-world experience. The eXplorist.life videos, which I find very informative, indicate that 4 AWG works well in about 95% of their installations (I believe they do a lot of camper vans etc). Your setup is another good example of 4 AWG performing successfully, even at or near the charger's maximum output rating.

You're also absolutely right about cable cost. Good grief, I paid nearly $5 per foot for 4/0 cable the other day.

So why am I using 1/0 cable? Partly because I grew up on a farm where the philosophy was, "If four nails will hold it, use five screws."

More seriously, it's about efficiency. Output wattage cannot exceed input wattage minus conversion losses, and those losses include the voltage drop across the cables and connectors. Larger conductors reduce voltage drop, reduce losses, and allow the charger to operate more efficiently. 

That said, if I already had 4 AWG cable installed with a 30-amp charger and wanted to upgrade to the 50-amp version, I probably wouldn't replace the cable. The performance gain wouldn't justify the additional cost and effort in most cases.

[Geronimo John]

18 minutes ago, Dean and Mary said:

the required conditions are met, such as the driver's door being closed.

Wow, I did not know about the Door Closed condition!  I like it.  Also good to know when you are sitting there in the front seat looking at the numbers and not seeing any current and wondering WHY???????   

20 minutes ago, Dean and Mary said:

The Anderson SB175 supports cable contacts up to 1/0 AWG, while the SB120 is limited to contacts for up to 2 AWG cable, according to the Powerwerx specifications. Since I am running 1/0 cable, I ordered the SB175 along with the matching 1/0 cable contacts

The lugs inside the housing of the SB175 can also support smaller cables.... such as our #4 AWG wires.  The contact point of all the various lug sizes listed is the same.  I like having oversize contact points so went with the larger SB175's contacts with the smaller #4 lugs.  Besides the SB175 fits my hands better!  

GJ

 

[Dean and Mary]

9 hours ago, Snackchaser said:

My suggestion of using the 12 V wire from the 7-pin tow harness to trigger the Orion through its L input is gaining traction.  But it was only meant as a last resort if changes to the Orion’s settings didn’t correct the problem.  The preferred method is still automatic detection, and it will work best for most installations.

I appreciate the explanation of the potential issues that can arise when using the 7-pin tow harness to trigger the Orion. Those are important considerations and something I have spent a fair amount of time thinking about.

My plan is to use the 7-pin connection as a redundant method to ensure the Orion is powered down when the vehicle is not running. At the same time, I intend to configure the Orion's voltage-sensing parameters as if no external ON/OFF control were present. That way, the charger should still operate properly based on voltage conditions, while the 7-pin trigger provides an additional layer of assurance that it remains off when the tow vehicle is shut down.

 

[Dean and Mary]

1 minute ago, Geronimo John said:

Wow, I did not know about the Door Closed condition!  I like it.  Also good to know when you are sitting there in the front seat looking at the numbers and not seeing any current and wondering WHY???????   

Oh, my mistake, I thought I had read that and trying to confirm and found I not to be true. Sorry for that misinformation. 

 

4 minutes ago, Geronimo John said:

The lugs inside the housing of the SB175 can also support smaller cables.... such as our #4 AWG wires.  The contact point of all the various lug sizes listed is the same.  I like having oversize contact points so went with the larger SB175's contacts with the smaller #4 lugs.  Besides the SB175 fits my hands better!  

 The Anderson SB175 can be used with 1/0, 1, 2, 4, or 6 gauge wire. It does fit the hand better and I added the handle kit. 

[jd1923]

51 minutes ago, Dean and Mary said:

John, I completely agree with what you're saying, and I've given this a great deal of thought.

And I agree with everything you wrote in these posts.

”The tables” re voltage drop and real world measurements are showing the tables are (engineered on purpose) to be conservative.

Maybe you already purchased the Orion 50 and if so perhaps it could be returned. I believe with 1/0 wire installed you can exceed 50A. I’m in the 40s in the Orion 50A with only 4 AWG and the Orion 70A could be getting over 60A.

At the same time, I truly understand if you’re about done with sourcing parts, the hardest, longest part of any DIY effort!😎

Edited 8 hours ago by jd1923

[Dean and Mary]

5 hours ago, jd1923 said:

Instead of adding pigtail cables, wouldn't it be a simpler the strip the 1/0 wire and then trim the copper strands down in size to fit the terminals? The pigtails adds more cost, more resistance in connections and additional points of failure. I imagine trimming the wire size would not be "to code" but it's the way I would do it for simplicity.

Yes, I agree. These wire reducers, shown below, may be a little too large to fit, but I'm going to give them a try. If they work, they should eliminate the additional connections and potential failure points you mentioned, which would make for a simpler and more reliable installation.  

 

 

[Dean and Mary]

10 minutes ago, jd1923 said:

Maybe you already purchased the Orion 50 and if so perhaps it could be returned. I believe with 1/0 wire installed you can exceed 50A. I’m in the 40s in the Orion 50A with only 4 AWG and the Orion 70A could be getting over 60A!😎

John,

Yes, I had already purchased the 50-amp Orion and have it mounted, although I haven't run any of the wiring yet. I also purchased the Mobile Solar fan because my installation requires the charger to be mounted horizontally.

Had the 70-amp Orion been available before I made those purchases, I likely would have gone that route. At this point, however, I'm committed to the 50-amp setup. If the Orion 50 ever fails, I would probably replace it with the 70-amp version.

I am curious how many changes Victron actually made between the 50-amp and 70-amp models. From the outside, it appears that much of the increase may come from the addition of active cooling and perhaps some upgraded output-stage components.