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 15 hours ago 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 12 hours ago 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!