DC - DC Charger Project

[Yoda]

Yoda -- I did what Jim suggested on my install. The wire is disconnected where the 7-pin wiring (trailer side) joined the OEM wiring. (Snip below taken from my Master diagram.)

Guest

Thanks you two - now I really need to change out the junction box (I got the one Howard used last year - or was it the year before?). But last year after opening up the existing rats nest to tie into the reverse wire, I put it off.

Jim - Now to the back feed issue ....you made me realize the charge current could be higher than the truck wiring could take depending on the TV battery state of charge. I had dismissed it based on the charge voltage being within limits, but the truck wiring current limit (I think is 30a) could be easily exceed. Just so you two know - if I bang my head too many times against the king pin fixing this you will hear about it.

NickinCO I believe Ted TedS is correct on the emergency break pulling its power form the trailer batterys. It gets power from the factory buss bar if I remember correctly after chasing down all the wiring that was connected to it during my Victron install.

Thanks everyone...It amazing how the to-do list expands after a chat here

Keith

On edit I forgot to mention I will be using my running lights for the D+ signal to turn the Renogy on as others have done.

[Yoda]

Yoda -- I did what Jim suggested on my install. The wire is disconnected where the 7-pin wiring (trailer side) joined the OEM wiring. (Snip below taken from my Master diagram.)

Howard - do you have a link to this diagram. I went looking for it, but did not find it. I even went back through you DC-DC install thread - maybe I missed it.

[NickinCO]

Renogy said the exact opposite. They recommend in thier instruction and when I called on wire sizing, to run a separate dedicated circuit. The only consistent ground between the TV and trailer is the 10awg charging wire. Yes the hitch can offer a ground path, but it can be intermittent at times like on a rough road. There is no way 10 awg can handle 60A.

You Victron is a 30A unit and can probably pull more than 30A. It 's possible your 2022 F350 wiring could handle that, but I have not read that far in the online manual yet to know what the charge circuit is rated at.

Theses are just my thoughts on this and I could be wrong.

Merry Christmas and Happy New year

That’s interesting… maybe I need to contact them again. I will run some tests to check braking with the trailer charging wire disconnected. I agree there’s no reason for it otherwise. If the sole reason is for not back feeding the TV it seems like that would be easy to test. I’d be willing to bet modern tow vehicles have a diode preventing this (just like your solar panels). If not it would be easy to add one.

From what Battleborn said the non-isolated Victron 30A charged only has one ground port. The isolated version has a ground on both input and output side. Reading on other forums it appears many people have used the non-isolated version and only grounded onto the trailer chassis. I will probably ground mine to a common bus bar.

[howson]

Howard - do you have a link to this diagram. I went looking for it, but did not find it. I even went back through you DC-DC install thread - maybe I missed it.

There's a PDF attached to this thread: https://gdrvowners.com/forum/operati...lts-f-350-mods

[Yoda]

Update howson

I know a lot of folks have been looking for the alternator specifications
My Ford dealer came through.
Attached is the at idle performance of the 2022 240A and 157A alternators included in the 6.7 HD (397A) option - standard if you get the instant cab heat.
highlighted alternator specifications.pdf
I wish I knew how to have the picture view show up.

This information is also available through the Ford Professional Technician System so should be available for other alternators too.

Also the instant cab heat is driven by 3 separate 50A relays, so I assume it draws somewhere close to the 150A when running. With 247A at Idle available I should be good withe 60A DC-DC running, just not withe instant cab heat on.

Hope this helps
Keith

[Guest]

Yoda , it makes sense when charging Li batteries at a higher voltage than that for flooded cell batteries to disconnect the B+. The truck batteries may get a slight charge from the dcdc charger output with the higher voltage. The alternator diodes will keep current from going back into the alternator( or maybe that is old school considering today's smart electronics).

Ted,

The diode feedback concern was from a smart alternator maker. A positive 7 way terminal left in tact will be backfed by the Renogy and could mess up the TV charge strategy but it would not harm the diodes even though it should not be done. The diodes are harmed by applying a heavy load to the TV at idle where cooling is minimal.

Jim

[Scott'n'Wendy]

Welding wire charts use 40C as the ambient temperature and the current shown is that which will not raise the wire temperature to more than 105C from 40C. That is a 65 degree rise at the chart current.

That's not what the 105* means, But I don't want to clutter Yoda's thread further so I better stop debating.
All good!

[howson]

Yoda
Attached as a pic and also attached the PDF.

[Yoda]

Yoda
Attached as a pic and also attached the PDF.

Thanks Howard. How did you do that? Did you convert the pdf to a jpg?

[Guest]

There is another helpful tool in windows referred to as "Snipping Tool" Used to be "snip it". It will copy anything you drag across on the screen and save as a PNG.


Jim

[Yoda]

There is another helpful tool in windows referred to as "Snipping Tool" Used to be "snip it". It will copy anything you drag across on the screen and save as a PNG.


Jim

I never knew that existed
Keith

[Guest]

I never knew that existed
Keith

Your going to love it.

Bring up the app, save it to your lower task bar. Click on it and select "new" and drag diagonally across what you want to copy and save.

Did two things useful today. The other was speaking with my parents security folks over the smoke detectors going off from my dad cooking and taking a nap at the same time. All is good. LOL. So this will be me when I'm 90 I suppose.

Jim

[Scott'n'Wendy]

There is another helpful tool in windows referred to as "Snipping Tool" Used to be "snip it". It will copy anything you drag across on the screen and save as a PNG.


Jim

And for those Mac people the program is called 'Grab'. Does the same thing as Snippit.

[howson]

Thanks Howard. How did you do that? Did you convert the pdf to a jpg?

Yes. In the full version of Acrobat X it's possible to save a PDF page as a JPEG.

The pic below showing the menu tree for this option was created by:

1) hitting PRINT SCREEN on my keyboard which takes a snapshot of the entire screen.
2) Pasting the snapshot into a Powerpoint slide.
3) Cropping the image down, add the arrow, and then use the Snipping Tool to grab just what I want.
4) Save the Snip as as standalone JPG (which I do a LOT here) and post it. Pic ends up "just right" for this forum.

Howard

[Yoda]

Yes. In the full version of Acrobat X it's possible to save a PDF page as a JPEG.

Your putting me in the poor house - all I have is the free version. I guess I could drop SWMBO or my daughter a hint - maybe for my birthday in January.