Simple option for DC-DC charging from tow vehicle?

[sbsyncro]

Yes I'm using the dumb ones. 4x 24/48 8.5a and 2x 24/12 70a

It's not the bms but the voltage has to be high enough to charge the batteries. Turn the pot all the way up and see what happens, along with drain the batteries down. This is all very simple to see if you have a shunt like victrons smartshunt.

Thanks I'm using the shunt built into the BMS - not perfect but it least it gives me a picture of what is happening at the "source". I've put on a 500w load and will let it run about an hour or so and check it

 

[justinm001]

Thanks I'm using the shunt built into the BMS - not perfect but it least it gives me a picture of what is happening at the "source". I've put on a 500w load and will let it run about an hour or so and check it

While you're at it turn the Orion on and see how many watts the load is pulling from the battery then turn it off and see. I'm betting it's 100-110w less when on

 

[sbsyncro]

While you're at it turn the Orion on and see how many watts the load is pulling from the battery then turn it off and see. I'm betting it's 100-110w less when on

just checked. no difference.

 

[sbsyncro]

OK so I took it down to 55% (13.07v resting), fired up the tow vehicle (putting out 14.2v), let it run for a minute and still nothing coming through. I'm wondering if I might have an issue with the way I have the circuit grounded? I'm grounding the trailer junction box to the trailer chassis and also the battery is connected directly to the chassis, so there is a common ground on the input and output sides of the Orion.

 

[Cal]

I've searched and read a lot of posts and all discuss one of two scenarios: (1) charging directly from the 7-pin without a dC-DC controller or (2) running a heavy gauge wire pair from the tow vehicle to a dedicated high-amp connector on the trailer and using a high amperage DC-DC smart charger. I'm considering a simpler "hybrid" solution that seems to provide some benefit but eliminates the need for running that dedicated circuit & connector (and uses a much less expensive DC-Dc charger) but didn't find any previous posts that address my remaining question.

Thanks in advance!

Is it too late for another option?

Run a 120V AC line to the trailer. Install an inverter in the vehicle and charge battery with a converter.

 

[sbsyncro]

Is it too late for another option?

Run a 120V AC line to the trailer. Install an inverter in the vehicle and charge battery with a converter.

Hmm. I have an AC-DC charger in the vehicle. But this approach would require me to install additional wiring between the vehicle and trailer, and thats one of the things I'm trying to avoid.

 

[Cal]

Yes, more wires, but orders of magnitude simpler than 12V and high current. All you need is a couple of extension cords. Plug them together at the hitch.

 

[HRTKD]

[Is there a way to multi-quote in replies...?]

Highlight the text in a post that you want quoted, then hit the Reply button that comes up after highlighting. Or, just hit the Reply link to quote the entire message. That will populate the quoted text at the bottom of the page. If you wish to add another quote to your reply, just do the same thing again. It will add the new quote to your existing reply.

 

[HRTKD]

My understanding of the "Isolated" version of the Orion is that it needs dedicated positive and negative lines. Using a common ground is for the non-isolated version.

 

[justinm001]

My understanding of the "Isolated" version of the Orion is that it needs dedicated positive and negative lines. Using a common ground is for the non-isolated version.

They can use a common ground but have the option to isolate the ground. OP does need to use both ground terminals which it looks like he does

 

[sbsyncro]

Highlight the text in a post that you want quoted, then hit the Reply button that comes up after highlighting. Or, just hit the Reply link to quote the entire message. That will populate the quoted text at the bottom of the page. If you wish to add another quote to your reply, just do the same thing again. It will add the new quote to your existing reply.

Ah! Just keep hitting reply to the various posts - thank you!

My understanding of the "Isolated" version of the Orion is that it needs dedicated positive and negative lines. Using a common ground is for the non-isolated version.

I think this must be my problem. My tow vehicle ground (in the 7-pin harness) is tied to the trailer chassis, thus both Neg terminals on the input and output of the Orion are grounded to the trailer (and vehicle) chassis.

They can use a common ground but have the option to isolate the ground. OP does need to use both ground terminals which it looks like he does

So can the "isolated" version (like I have) be used for non-isolated applications? If so, then perhaps this is not my problem....

 

[justinm001]

So can the "isolated" version (like I have) be used for non-isolated applications? If so, then perhaps this is not my problem....

Yes as long as both negatives on the Orion are used it'll act the same.

 

[sbsyncro]

Yes as long as both negatives on the Orion are used it'll act the same.

Hmm.. That leaves me just scratching my head then...

 

[JS43]

Coming back to this discussion after installing the Orion TR 12/12 -9 (isolated) into the trailer with some questions for the electrical gurus here. I'm getting an unexpected result that I am not able to figure out: (note this is not the "smart" version - the only thing adjustable is the output voltage via a trimming pot)

1. Input side is connected to trailer plug (+) terminal (rated at 15 amps from Jeep).
2. Output side is connected to LifePO4 battery in trailer
3. Output voltage adjusted to 14.6v per recommendation from battery mfg. measured before being connected to trailer battery

Resting voltage on trailer battery is 13.3v
Output from Jeep while running is around 14.1v (measured both at the trailer connection and the input side of the Orion)

Problem: I'm only getting 13.3v at the battery while the tow vehicle is running, despite the Orion's output being connected to the battery (which is 14.6v when not connected to the battery). I've also checked the BMS and verified that there is no current inflow to the battery (no charging effect).

Somehow I'm getting no contribution from the Orion, despite it seeming to perform as expected when not connected to the battery.

For those that are going to say "you should have gotten the Smart version - thats a "real" DC-DC charger", yes, I know that would have been ideal, but (1) it would not have fit the space (2) I was trying to KISS and (3) trying to keep costs down and the extra $100 is not something I wanted to spend, as I really only intended this as a "trickle charger" type solution while underway (read my original post at the beginning of the thread). I have friends successfully using this approach, so I can't understand why my setup isn't working.

Thanks in advance for any advice.

Keep in mind that Jeep, and Chrysler in general uses the smallest wire they can get away with on each circuit. That cuts down on their costs. They also use cheap insulation on the wires. Every time I have added something to my truck I end up changing the original wiring to handle the added load. I have had their original wiring get hot enough you feel it. I have also seen factory wiring go up in smoke because of the cheap tiny wires and insulation.

 

[Aussieguy]

Do you even need the dc-dc ?
If you are just going away weekends then use the solar and 7 pin
hopefully they will replace........ or get close to the power you used over night..
When you get home plug in the shorepower or let the solar finish the charging to 100% while you are not using it.

I would look at getting a second panel, use as ground mount that you can hopefully find sunlight.

My2c
If longer trips and if you have to rely on dc-dc while driving.......
get one that will at least do 20amps and rewire the jeep-trailer to get max performance.
Jeep should handle a 20amp draw from battery/alternator

getting a small dc-dc with only 9amps output is no better than just allowing the 7pin to do the charging.
and you still have to check your wiring whatever size even for the small dc-dc

hunting in forest .... solar may not be the greatest.
consider a small 800-1000w generator to power your converter for a couple of hours .
tractor supply has a sportsman model .... nice green color.
But don't run it during prime hunting hours ....or other hunters may just shoot it