DC/DC Charger Sporadically Works

[John Spilker]

I have a 2021 Airstream 22fb Caravel.

About 2 1/2 years ago, I installed two Battle Born lithium batteries. They work well and no problems.

My TV is a 2021 Toyota Tundra with a Smart Alternator.

About 2 years ago, an Airstream dealer installed a 30-amp Victron Orion DC/DC charger. I'm not sure they had ever done this before as I had to return twice to the dealership to get it to at least turn on.

Battle Born suggested that I change the absorption rate to 14.4 volts. That is the only change that has been made to the Victron app.

Yesterday, I had a 5-hour drive back home and noticed at the midway point the batteries had lost about 10 percent of capacity. When the truck was stationary, I started the engine and checked the DC/DC charger. It turned on, and after 2 minutes (configured for 120 seconds) and it momentarily charged the batteries and almost immediately it reported it was in Off mode. A few minutes later, it reported Bulk Charge and then went to Off.

On the next portion of the drive, I turned the vehicle lights from Auto to low beam. When I got home, the batteries were 100% charged.

Could turning the lights on to low beam have changed the charge state of the converter? Could the extra load on the alternator impact the DC/DC charger. If so, is there something in the Engine Shutdown Detection app setting that I should change such as the Start Voltage? I've seen a video that suggests changing the setting from 14 volts to 13 volts overcomes this type of problem, but I don't want to do anything that impacts the alternator. Or is there something else I should be looking at.

Thanks

[hikingcamera]

I've had issues with the DC to DC as well. Also a Victron 30 amp. Currently it's been blowing the 30 amp fuse in my truck pretty consistently. The dealer has it now and is looking at it. I haven't heard anything back yet, but we also ended up putting a deposit down on a new Trade Wind which we'll be picking up later this month, so I don't expect to get any answers from them. I anticipate the next time we see our Flying Cloud will be the last as we move everything from it to our new trailer.

If yours is coming back on, it must not be the fuse, though may be worth checking what amperage your fuse is. I am hoping that the 12 amp DC to DC in the Trade Wind will not blow the fuse. One option is to get separat cabling for the DC to DC (using an Anderson connection from the trailer to the TV). You could then also get a bigger DC to DC assuming your alternator will support that. That could be the issue, does your alternator have enough juice? Or if you have the hybrid engine, is there some weirdness going on there? Unfortunately I'm not much help, but I can tell you, you are not alone!

[JeffKim]

You might want to check the specs with the Victron 30A. I know with the Victron 18A, it can draw up to 25A, it's only the output that is limited to 18A. So, your 30A might be pulling more current from the TV than it can handle. It makes sense that increasing the voltage output will draw more current.

@HC, I think they might have put the 12A DC-DC in the Trade Wind so it works with most every TV. For example, our Q7 charging wire is fused at 15A.

[hikingcamera]

Originally Posted by JeffKim

You might want to check the specs with the Victron 30A. I know with the Victron 18A, it can draw up to 25A, it's only the output that is limited to 18A. So, your 30A might be pulling more current from the TV than it can handle. It makes sense that increasing the voltage output will draw more current.

That makes sense. I don't understand it all that well. I wonder if my dealer installed too powerful a DC to DC. Unfortunately I cannot see any way to adjust the amps it will draw, though that would be nice to limit it like you can a multiplus.

Originally Posted by JeffKim

@HC, I think they might have put the 12A DC-DC in the Trade Wind so it works with most every TV. For example, our Q7 charging wire is fused at 15A.

Agreed. That's my hope. It should be sufficient for my use case. And potentially it would be easy to upgrade. Though if I really wanted to charge my batteries faster on the go, I think installing a front-facing SmartPlug inlet and connecting my trailer to the built in Pro Power would yield better results.

[G8trwood]

Only the newest 50a model lets you set the draw.

Make sure and check your settings for voltage for shutdown voltage, etc. I had to set mine at 8-9v . Several, posted settings in another thread. The smart alternator and computer controlled charging circuits can be a pain. My old Ferd just had straight 30a and worked great. The new Ford, well, computers you know. I will end up running a dedicated circuit from the battery to bypass this issue.

[FilmGuy]

Originally Posted by John Spilker

Could turning the lights on to low beam have changed the charge state of the converter? Could the extra load on the alternator impact the DC/DC charger. If so, is there something in the Engine Shutdown Detection app setting that I should change such as the Start Voltage? I've seen a video that suggests changing the setting from 14 volts to 13 volts overcomes this type of problem, but I don't want to do anything that impacts the alternator. Or is there something else I should be looking at.

Thanks

Yes, depending on how the control circuitry to the DC/DC is wired, it's very possible for the lights to be a switch to tell the DC/DC to operate. It can also be set to sense the alternator, but setting that up is tricky with a smart alternator. (It's a bit tricky in any case.) And it's possible for both of those things to be active at the same time.

One of the easiest ways to turn a DC/DC charger on while ensuring that it doesn't drain the TV's battery when the vehicle isn't running is to wire a lead from the light circuit to the DC/DC's "Allow to Charge" input so the running light circuit turns it on. The installer may very well have done this. (But if they did, they should have told you, so you knew to turn the lights on.)

[Wazbro]

It' possible your "smart" alternator drops the voltage too much and turning on the lights signals your alternator to increase voltage. My Chevy owners manual does say turning on lights signals alternator to stay out of low voltage setting.

[richard5933]

Couple of things...

1) The output on the Victron DC-to-DC chargers is what's usually regulated, but the input current to get that prescribed output will vary according to the input voltage.

The formula at play here is WATT = VOLTS x AMPS. In this case, the output side can be measured in watts. As the input voltage fluctuates, so will the input current draw as the device attempts to maintain a constant output.

So if your smart alternator drops the voltage as the tow vehicle battery becomes charged, the DC-to-DC charger will increase the input current to offset that so that it can maintain a constant output. As the input voltage drops below the output voltage, the DC-to-DC will draw higher current on the input side.

This is likely why your is blowing the 30a fuse even though it is a 30a charger. That represents the output of the charger, and for the DC-to-DC charger to do that it will have to draw much more than 30a if the voltage is lower than the output voltage.

2) It's possible that the DC-to-DC charger was not installed with a proper sensing wire to cause it to turn on when the vehicle is running. On an old-school alternator this was more simple - the DC-to-DC used a sense wire to know when the TV's alternator was outputting above a set voltage. With today's smart alternators this doesn't work so well.

To override this, some people use a power feed from the running lights circuit on the TV as the trigger for the DC-to-DC to turn on and start making power inside the trailer. This means that your running lights must be turned on when towing in order to enable the DC-to-DC.

Others (like me) have installed a toggle switch on the tongue of the trailer and manually switch on the DC-to-DC charger. When we stop somewhere it's just part of my walk-around inspection to flip off the DC-to-DC toggle to keep from running down the TV battery while parked. As a safety, I also have the automatic cutoff set to turn it off when the input voltage drops to a certain set point in case I forget.

There a a few other methods of triggering the DC-to-DC to turn on, so check the manual to see how to best reconfigure yours.

[jec1]

I did the lithium upgrade and installed a Victron DC-DC charger on our Globetrotter 27. Initially, I had problems similar to what you described, the charger would switch on and off seemingly randomly. Long story short, the wire size I used was a very tight fit into the connection on the charger, and a couple of the fine strands did not make it in the terminal strip hole and were intermittently shorting out with the negative wire. I corrected this, problem solved.

[uncle_bob]

Hi

Simple answer: The 30A DC/DC is *way* too big. No matter what your tow vehicle, it will not work properly through the 7 pin connector. Something like the 18A may or may not be too big. Many folks get a programable version so they can "tune" the current limits with the app.

Solutions:

1) Run a dedicated pair of number 6 cables from the front of the vehicle to the back bumper. Then hook it up with some Anderson Power Pole connectors. Next add a similar pair of cables on the trailer to feed the DC / DC. Hopefully the alternator in the tow vehicle will be able to feed the load without burning out ....

2) Get a more appropriate DC / DC and replace the one you have. Swapping them out is not all that hard. There are several to pick between. ( The 8 to 12A versions with no programmability, the 18A with some programability, the 25 and 50A with *lots* of programability (for $$$$). )

Bob

[Life is a Highway]

Any unit can fail?

You should be running an Anderson Connector to the DC Orion and it should be heavy enough wire gauge to handle the voltage drop and amperage

I would suspect that you have an alternator drive belt slipping or failing or an alternator failing.

Now it all starts at your battery can the vehicle battery pass a load test and are the cable connections to the battery and alternator secure.

In the trailer are the wires to the Orion secure tight ? And to the batters in the trailer are they tight.


I wired my truck Ronnie Dennis did our trailer I started with one 30 Orion this spring had a second installed. No issues

[BGClassic]

Not to pile on, but my take-away on this thread is the DC-DC charger needs a pair of dedicated 4AWG (or better) cables from the battery to the bumper. I have two alternators (390A) and two batteries and am not even sure 4AWG is sufficient since my lithium batteries are now inside over the axles, a long run.

I am waiting for the new Orion XS, since it is adjustable, and I believe it can accept larger AWG wire than previous models.

[PaulinVA]

Some great feedback on this problem. If I read the OP correctly, the charge flaw was overcome by turning on the lights. Could that be the most direct and least intense method to overcome the problem.

[Mikebrady62]

Originally Posted by PaulinVA

Some great feedback on this problem. If I read the OP correctly, the charge flaw was overcome by turning on the lights. Could that be the most direct and least intense method to overcome the problem.

The way my backup camera is wired, I need to turn on mu running light to power it. The DC-DC charge could possibly be wired the same way.

[jnm30327]

As others have said, the 10 AWG charge wire for the DC-DC Charger is woefully inadequate. The unit interprets the voltage drop as a car shutdown. Also, there is risk of losing the use of the trailer brakes.

See my story here with a similar setup.

[uncle_bob]

Hi

Ok, if we need more details:

The typical DC/DC sits there looking at the input voltage. After a while (10's of seconds) it decides the voltage is OK.

It then starts ramping up the output current. This also probably is a 10's of seconds sort of process.

As the output current goes up, the input current also goes up. That increases the drop in the wires to the unit. This drop can easily be many volts.

As the voltage drops, the DC/DC eventually decides the voyage is too low. It then disconnects from the circuit.

Once disconnected, you are right back to the "wait for the voltage to be ok phase.

The net result is a "burp burp burp" sort of current flow going into your batteries. Your vehicle's alternator is also seeing this same series of load spikes. None of it is a good thing. The cycle could take anything from a minute to ten minutes to complete depending on the model of DC/DC and its settings. In the case of a 30A DC/DC, you will never get to "full output" on the device with a normal 7 pin setup.

You might take a look at your alternator. It probably has a very impressive current rating number on it. That number is at a lot of RPM's on the device. It also is for an (normally unstated .... brief ... ) period of time. (yes, there are other constraints as well ...). Best guess, figure it will put out half that number full time. You could still be overestimating the capacity ....

Bob

[Saullman]

you may very well have one of the recalled Orion DC-DC Chargers. There's a list of serial #'s that we're affected, ive had to replace (2) under warranty. You'll need to get to the serial tag take a picture of it then see if it is in that range. The good news they have a 5 year warranty. But because of these factory defects the warranty doesn't apply, & they will be replaced with new good units.