DC to DC troubleshooting

[jd1923]

4 hours ago, Dean and Mary said:

Most voltage drop calculations focus on maximum current, but the Orion's charging current changes significantly as it transitions between bulk, absorption, and float stages.

After some on-the-road use, you'll find that all that matters in a DC-DC charger is that it turns on to BULK charge and gives you 40 to 50Ah for every hour towing.

Absorption and float are final charging modes used to bring SOC up to 100%. BTW, this was a lot more important for LA batteries vs. LiFePO4. Our solar charger will bring SOC up to 100% when parked at home. When traveling we are most often between 50% to 80% SOC, so the Orion is almost always in bulk charging mode when towing.

My goal is tow a half day and add 200 Ah to battery SOC for when we get to our next campsite! 😎

Edited Sunday at 07:53 PM by jd1923

[Snackchaser]

20 hours ago, Dean and Mary said:

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.

The idea could work if you want additional assurance that the charger powers down.  But use the H pin (remote on/off), not the L pin, and remove the L–H jumper, because a signal on L overrides the voltage detection and forces the Orion on, the opposite of what you want.  Remote on/off on H acts as a permission where the Orion only charges if H is high (12 V) and the normal voltage conditions allow it.

However, Victron’s manual says to turn the voltage detection off when using remote H signals. . . so it may not work as you intend.  Test it to assure that both conditions (voltage detection and H pin) will work together.  Verify that with the engine running and the 7-pin unplugged, the Orion powers down.

Hope it works for you!  Geoff

I added an edit because this is hard to wrap one’s head around it, and when better explained you might change your mind.

You can’t use the L pin for a redundant shutdown because L is only a trigger for “on”.  When the L signal goes dead, the Orion just falls back to its voltage detection to turn off.

The H pin is needed for shutdown.  If the Orion fails to see that the engine is off because of incorrect settings, it could stay on.  With the 7-pin wire on H, and the L–H jumper removed, the 7-pin goes dead when the engine is off, and that turns the Orion off .

Victron suggests turning off voltage detection when using H.  Either way, a dead H pin shuts the Orion off.  What’s uncertain is whether the voltage detection also stays active as a backup if you leave it on, so test it.

Having said that, I’d reconsider the idea altogether because I don’t believe there is a credible failure mechanism that necessitates using pin H.  We forget that Orion has an “Input voltage Lockout” feature with default setting of 12.5 volts which would shut it down probably leaving enough TV battery for a start.

We seemed to have digressed from the real benefit of using Pin L to turn on the Orion when quirky smart alternators fail to do so.

Edited Sunday at 10:54 PM by Snackchaser

[Dean and Mary]

1 hour ago, Snackchaser said:

The idea could work if you want additional assurance that the charger powers down.  But use the H pin (remote on/off), not the L pin, and remove the L–H jumper, because a signal on L overrides the voltage detection and forces the Orion on, the opposite of what you want.  Remote on/off on H acts as a permission where the Orion only charges if H is high (12 V) and the normal voltage conditions allow it.

However, Victron’s manual says to turn the voltage detection off when using remote on/off. . . so it may not work as you intend.  Test it to assure that both conditions (voltage detection and H pin) will work together.  Verify that with the engine running and the 7-pin unplugged, the Orion powers down.

Hope it works for you!  Geoff

Thanks Geoff. Since I will have a switched positive signal available from the 7-pin connector whenever the vehicle is running, my plan was to use that signal to pull the H-pin high and turn the Orion XS on.

While reading through the Victron documentation, I came across the statement: "Engine shutdown detection should be switched off in the Victron Connect app because physical control via the H-pin tells the charger explicitly when to turn on and off." Your above statement is correct and confirmed, so not sure I need to test it. 

Okay, I am now rethinking my installation choices. I asked AI to list the disadvantages of using the H-pin & came up with this: 

When you bypass the integrated Engine Shutdown Detection feature on the Victron Orion XS and instead use the Remote H-pin connected to an ignition source or a physical switch to turn the unit on and off, you introduce several distinct disadvantages:

• High Risk of Starter Battery Drain: If the vehicle's ignition is left in the "ON" or "Accessory" position without the engine actually running (e.g., listening to the radio, updating software, or running diagnostics), the H-pin will see voltage and force the Orion XS to start charging. At its full 50A capacity, it can rapidly drain or damage your starter battery in minutes. [1, 2, 3, 4]
• Increased Wiring and Installation Complexity: One of the core benefits of the Orion XS is that it can detect whether the engine is running purely by analyzing the voltage on the main heavy-gauge power lines. By turning detection off, you are required to physically fish and route a separate, auxiliary signal wire from your vehicle's fuse box or ignition circuit all the way to where the charger is mounted. [1, 2, 3]
• Loss of Alternator Overload Protection: When Engine Shutdown Detection is active, the Orion XS constantly monitors input voltage and can dynamically scale back or temporarily pause charging if the alternator's voltage dips below a safe threshold. Forcing the unit on via the H-pin and disabling detection strips away this intelligent automated cushion, meaning the charger could overwork a smart alternator at idle.

This second bullet point does not really apply to my installation, since I already have a dedicated wire from the 7-pin connector terminated in the trailer. However, the other two bullet points have me reconsidering whether I want to use H-pin control at all. At this point, I don't believe I will use that option. 

That brings me back to my original plan of using a physical switch inside the trailer to enable or disable the L-pin-to-H-pin jumper. I would also have the option of controlling the charger through the GX device or simply unplugging the cable to the tow vehicle.

My main concern is those situations when it is late, you pull into a place like Cracker Barrel for the night, and you do not unhitch. In that scenario, being able to flip a switch inside the camper provides peace of mind. It is a positive way to ensure the Orion cannot draw power overnight, regardless of any software settings, detection logic, or wiring configuration.

I appreciate being able to use the forum members as a sounding board while I work through these options. Discussing the pros and cons with others often helps me think through scenarios I may not have considered and ultimately arrive at a solution that best fits how I actually use the trailer.

[Snackchaser]

@Dean and Mary Please go back and read my edit on the previos post, it may shine a new light on things!

[Dean and Mary]

16 hours ago, Snackchaser said:

Please go back and read my edit on the previos post, it may shine a new light on things!

@Snackchaser Yes, I understand and agree with the edit. 

My current plan is to use a simple manual switch to interconnect the L and H terminals, allowing me to remotely activate via the Orion XS as needed. That approach lets me take full advantage of the unit's built-in engine shutdown protection without relying on any automated control of the L or H pins.

Thanks, Dean

[Snackchaser]

1 hour ago, Dean and Mary said:

My current plan is to use a simple manual switch to interconnect the L and H terminals

That’s a solid plan, the switch can replace the factory L–H bridge.  There’s also a toggle in the Victron app if you ever want to switch it off without a physical switch.

Good discussion!  Cheers!

[jd1923]

On 11/9/2026 at 9:54 AM, Snackchaser said:

There’s also a toggle in the Victron app if you ever want to switch it off without a physical switch.

The screen below clearly shows the Orion DC-DC charger is OFF (left frame). When you click on the message, "Why is the charger off?" you get 3 reasons.

In the setup, I clicked the app toggle Charger enabled to OFF, the option Geoff had mentioned which is given in see reason #3. Notice the warning message when using the app switch to disable charging (middle frame).

As soon as the TV ignition key is turned OFF reason #8 will appear since the engine detection will immediately show <12.9V (configurable). A sitting lead acid starter battery in good condition should read about 12.6V.

Reason #1 is Low Input Voltage which occurs as soon as you physically disconnect the DC-DC cables at the Andersen terminal at the bumper. You can see that looking at the first screen where it shows 13.5V on house batteries and 0.0V on the starter battery since is is disconnected (OFF reasons in right frame).

If I needed a 4th method to turn OFF the Orion, e.g. for servicing the system, I would throw the 60A breaker under the dinette seat which connects the Orion charging output to the main positive bus. When both the breaker AND the Andersen connector are OPEN the Orion will have no possible voltage on either end, so will be fully powered down.

Gosh, if a 5th way to ensure the Orion is OFF is truly needed, please add the switch at the hitch or within arms length under the doghouse. If I had to climb back into the cabin just ONCE to turn the Orion ON when we're packed and ready to tow, it would be the last time. I would delete that switch leg asap. 🤣

But that's just me, keep it simple. BTW, the switch for our LiFePO4 batteries is a 1/2" wrench to the main ground wire. It works every time, no added resistance, no additional points of failure! 😎

Edited 1 hour ago by jd1923

[Geronimo John]

You guys totally lost me on the H and L pins.  Suspect some others are not following that as well.  So more AI homework that explains what they do, and how it applies to both the 30 and 50 amp versions:

AI Overview

 

No, both units actually share this identical hardware feature. The factory-installed wire loop bridge between the remote L and H pins is present on both the older Victron Orion-Tr Smart 30A and the newer

Victron Orion XS 50A models. 

 

 

 

How It Works on Both Versions:

• The Factory Setup: Both chargers ship with a small wire bridge (jumper loop) pre-installed into the green remote terminal block connecting the L (Low) and H (High) pins. This loop tricks the charger into remaining in a constant "Remote On" state so it works right out of the box using just its internal engine-shutdown detection settings. 

• Disabling / Customizing: If you want to tie the charger to a physical toggle switch, an ignition-live wire, or a Battery Management System (BMS), you must pull that factory bridge out on either unit to utilize the individual pins. 

The Real Key Differences:

While they share the same style of remote bridge, the Orion XS 50A is a complete, ground-up redesign compared to the older Orion-Tr Smart 30A
 

Efficiency: The 50A model runs at an impressive 98.5% efficiency (meaning it stays incredibly cool and no longer features massive cooling fins), whereas the older

30A model runs at 87% efficiency and gets famously hot to the touch. 

 

Connectivity: The 50A unit includes a dedicated VE.Direct port to easily talk to GX devices (like a Cerbo GX), whereas the 30A unit relies purely on Bluetooth for communication. 

Adjustability: The 50A version allows you to precisely dial down the charging current via the app (from 1A up to 50A  to protect weaker alternators, while the older 30A version simply outputs its fixed max capacity when active. 

 

[topgun2]

1 hour ago, Geronimo John said:

You guys totally lost me on the H and L pins.

Dang - you're doing a bunch better than I am.

I currently have no intent on doing anything with DC to DC charging.  However, I still find the discussion interesting.

Bill