DC - DC Charger Project

[NickinCO]

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.

[howson]

Yoda Keith,

If your running a dedicated 2awg line(s) for your Renogy, disconnect the 7 way charge wire (leave ground in place for lights) since you do not want a dual path in charging or backfeeding to the TV. By doing this, your TV and RV will have complete isolation for charging the RV. You will also be set to reconfigure the Renogy with a few DIP switches for a future lithium conversion.

Jim

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]

Yoda Keith,

If your running a dedicated 2awg line(s) for your Renogy, disconnect the 7 way charge wire (leave ground in place for lights) since you do not want a dual path in charging or backfeeding to the TV. By doing this, your TV and RV will have complete isolation for charging the RV. You will also be set to reconfigure the Renogy with a few DIP switches for a future lithium conversion.

Jim

[Jlawles2]

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

[Scott'n'Wendy]

Scott'n'Wendy, It is the insulation that you don't want to compromise by overheating of the wire.

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.

[Yoda]

You may want to consider a split loom material or similar to protect the #2 from abrasion?

I got this stuff to try in 1.25" and 1" https://www.amazon.com/gp/product/B0...2?ie=UTF8&th=1 along with some rubber coated stainless steel clamps for the truck frame.

[Scott'n'Wendy]

You may want to consider a split loom material or similar to protect the #2 from abrasion?

[Hogdrv]

Sounds like you have a great plan 👍👏, hope your truck gets here soon. I was there this time last year waiting for my truck to show up, I ended up having the 5th wheel show up before the truck, but man was it worth it, I LOVE my truck!

Merry Christmas
Jim

[Yoda]

I understand, but the 105*C you mentioned is the insulation rating, not the wire.

Hogdrv TedS TravelHabit Guest

Just to put this all in perspective. I really appreciate everyone's thought and help.

Due to the fact theRenogy 60A DC-DC unit could pull close to 90A per reports, and after reading the Blue Sea and other ampacity tables, I chose to use 2 AWG cable, good for 100A @ 65' which is about the total run length of the system. Thanks to Jim I am fusing the battery connection.100A https://www.amazon.com/dp/B084LZ6D1V/ref=emc_b_5_t. Clean and simple and takes up a lot less space than a breaker. See Scott I followed 1/2 of your advice . Power will then feed through a 200A solenoid rated for continuous duty (switched from up fitter switches) to a bulkhead fitting in the truck bed. The bulkhead will house an SP120 Anderson connector.

Trailer side I will mount the Renogy 60A DC-DC unit to the ceiling of the front bay - only space I really have left. I will still use the 2awg wire back to the kingpin and then along the existing pigtail terminating in another SB120 connector. Going the other way, the output from the DC-DC (2awg) unit will go to an 80A Blue sea 285 series circuit breaker. https://www.bluesea.com/products/718...face_Mount_80A and then to the Lynx power in bar on my system. This bar is directly attached to the batterys.

If I have run the numbers correctly I should be well within the limits of the 2awg welding cable https://temcoindustrial.com/temco-wc...g-50-ft-black/ US made and rated -50C to 105C. I have 50' of black and 50' of red on hand.

Hopefully I have this figured out correctly. I have all the parts I need on hand or ordered. Now the wait for the new truck. Ill do it first and then see if I have enough cable for the trailer side (get more if needed).

I will also be leaving the stock charge line in place in the existing trailer plug. I see no reason to disconnect it. Thoughts?

Hopefully this brings everyone up to speed Again if I messed up somewhere, now is the time to wack me upside the head

Thanks

Keith

Merry Christmas and Happy New Year

[TedS]

Scott'n'Wendy, It is the insulation that you don't want to compromise by overheating of the wire.

[Scott'n'Wendy]

Keith was wondering about using ampacity to size wire.

Ampacity is the maximum current that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Current is measured in amperes or “amps.” You must use the correct size wire for the current (load) requirement of the circuit to prevent the wire from overheating.

I understand, but the 105*C you mentioned is the insulation rating, not the wire.

[TedS]

The 105*C is referring to the temp rating of the insulation, how much ambient heat it can take before melting, not how hot the wire will get when passing max rated current.

Keith was wondering about using ampacity to size wire.

Ampacity is the maximum current that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Current is measured in amperes or “amps.” You must use the correct size wire for the current (load) requirement of the circuit to prevent the wire from overheating.

[Yoda]

If possible, verify you can stuff #2awg into the 80A breaker terminals. Sometimes terminals are just big enough for their intended purpose. (#4)

Everything uses ring terminals, including the breaker so I should be good, but I know first hand what your talking about. One trick mentioned here is to use crimp on ferrets on stuff in connections. It compresses the wire into a very tight neat bundle.

Thanks for the heads up.

Merry Christmas.

[Scott'n'Wendy]

Update
I sent a question into Renogy on what size breaker to use on the output side. Manual says 75A or close. They recommended going withe 80A.
Keith

If possible, verify you can stuff #2awg into the 80A breaker terminals. Sometimes terminals are just big enough for their intended purpose. (#4)

[Scott'n'Wendy]

Max temp rating on the welding cable from the sire you referenced is 105 C. That's mighty hot.

The 105*C is referring to the temp rating of the insulation, how much ambient heat it can take before melting, not how hot the wire will get when passing max rated current.