DC - DC Charger Project

[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]

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?

[howson]

Yoda
Attached as a pic and also attached the PDF.

[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!

[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

[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

[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

[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.

[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.

[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.

[TedS]

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).

[Yoda]

Straight from My lithium Battery maker (SOK)- There is no reason to disconnect the 7-pin even with a DC to DC charger in place. This also powers your emergency brakes if you have electric brakes and is legally required. Also, I spoke with tech support at battleborn about the Victron DC to DC charger. They stated there's no reason to run a ground from the TV battery all the way back to the charger unit in the trailer. They recommended I buy the non-isolated version of the Victron DC to DC charger and ground it to the trailer chassis. I don't believe any back feeding occurs in any current tow vehicle, but cannot confirm. I cannot imagine there isn't a diode preventing this somewhere.

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

[Yoda]

Yoda Keith, let me know how that wire protector works and how you get it over the cable.

It going to be interesting - I already tried some (you scrunch it up like a finger puzzle an it doubles in size). It will take a bit of patience. But I think it can be done. The 1.25 is easier to work with than the one inch. the two 2awg wires measure 0.8 side to side.
Keith

[TedS]

The 105*C is for the ambient atmosphere around it, the wire will never cause it to come close to 105*C. It's so you know where you can run the wire. For instance, the lumex wire in your house is rated 90*C, but the wires in your house don't heat up to 90*C when you have a blow dryer going on high or the oven on broil.

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.

House wire charts use 30C as the ambient temperature and the current shown is that which will not raise the wire temperature to more than 90C from 30C(86F). That is a 60 degree rise at the chart current. There are derating figures to use to figure ampacity for other ambient temperatures.

[TedS]

NickinCO , the emergency brake function requires the trailer battery, not the tow vehicle battery. The 7-pin connection is already pulled apart if the emergency braking is necessary.