24V System Wire Sizing help

[JonBartee7]

so what would need to change in this setup if I mount the dc2dc converter on the breaker side of the rv?
lynx positive -> |010|030|->isolated_dc2dc_converter.in
lynx negative -> |010|UUU|->isolated_dc2dc_converter.in
dc2dc_converter positive-> | 010|030|->dc_distribution
dc2dc_converter negative <-| 010|030|<-dc_distribution

 

[John Frum]

well the only problem I'm thinking of with just using the ac2dc converter for dc power to all my appliances is that there is nothing to power my slide out, hitch jack, fridge, water pump, pepwave router, etc. if my inverter is off and I am not connected to shore power. I would like to have 12V dc running directly from batteries to dc distribution 24/7 to keep the fridge powered most importantly and be able to shut the inverter off overnight when not using ac applicances.

I dont think I mentioned but I live in my rv and travel full time so having these things all the time reliably is important.

I thought about a 48V system but 24V seemed to suit my needs best and I already have the 24v multiplus and 2* 12v batteries that will be connected in series for a 24V battery bank. It would be very difficult to pivot now.

You will need a 12 volt battery for the slide and hitch jack.

 

[John Frum]

so what would need to change in this setup if I mount the dc2dc converter on the breaker side of the rv?

Parsing error ^

lynx positive -> |010|030|->isolated_dc2dc_converter.in
lynx negative -> |010|UUU|->isolated_dc2dc_converter.in
dc2dc_converter positive-> | 010|030|->dc_distribution
dc2dc_converter negative <-| 010|030|<-dc_distribution

Parsing error ^

 

[John Frum]

You didn't include the circuit map for the dc distribution panel.
I doubt the high draw things like jacks and slides are even terminated there but it is important to be sure.

 

[John Frum]

Is this your floorplan?

Explore and learn more about Grand Design Transcend Xplor 231RK

Explore the top-rated Grand Design RV Transcend-xplortravel trailers. Exceptional design, value, and touring capabilities. Join the biggest RV community

www.granddesignrv.com

If yes, where is the system going and where is the ac/dc distribution panel?

 

[JonBartee7]

You will need a 12 volt battery for the slide and hitch jack.

Ya I plan to connect them from the 12v end of the 24 to 12v dc2dc converter.

You didn't include the circuit map for the dc distribution panel.

I attached the only information I really have about it from the manual of the rv or breaker box.

If yes, where is the system going and where is the ac/dc distribution panel?

Attached picture indicating ac/dc distribution panel and where my underpass storage is where the batteries/inverter/etc will be located

 

[John Frum]

Ya I plan to connect them from the 12v end of the 24 to 12v dc2dc converter.

That is very unlikely to work.
Those loads will have huge surge.

I attached the only information I really have about it from the manual of the rv or breaker box.

Do you not have the RV in your possession?

Attached picture indicating ac/dc distribution panel and where my underpass storage is where the batteries/inverter/etc will be located

Wow diagonally opposite corners, I would call that 80 feet round trip.

 

[John Frum]

I'm looking for the table that describes the circuit that corresponds to each fuse.
Same concept as the picture you showed of the circuit map.

 

[JonBartee7]

That is very unlikely to work.
Those loads will have huge surge.

so should I just replace the current 12v battery and have that dedicated to powering the slide/jack/etc? then I'd have to reinstall the old solar panel and charge controller to charge that

Wow diagonal corners, I would call that 80 feet round trip.

I mean, it's a 23 foot rv inside and 30ft from bumper to front of hitch so I don't see how it could possible be 40 feet diagonally. The breaker is about 2 feet into the rv and same with where the components will be in the passthrough storage on the other side.

I don't see how I could possibly have an 80ft roundtrip without adding 10 feet of length to the rv

I'm looking for the table that describes the circuit that corresponds to each fuse.
Same concept as the picture you showed of the circuit map.

I thought I had that in the earlier picture but I forgot the front panel was off. I attached the picture of the dc labels

 

[John Frum]

so should I just replace the current 12v battery and have that dedicated to powering the slide/jack/etc?

Possibly.
Devil is in the details.
I don't have enough detail yet.

then I'd have to reinstall the old solar panel and charge controller to charge that

Not necessarily.

I mean, it's a 23 foot rv inside and 30ft from bumper to front of hitch so I don't see how it could possible be 40 feet diagonally. The breaker is about 2 feet into the rv and same with where the components will be in the passthrough storage on the other side.
View attachment 96223
I don't see how I could possibly have an 80ft roundtrip without adding 10 feet of length to the rv

I'm guessing you will need to go around the periphery.
I could be wrong.

I thought I had that in the earlier picture but I forgot the front panel was off. I attached the picture of the dc labels

So the slide has a 30 amp fuse in the distribution panel but I don't see the jack.
That complicates things.

 

[JonBartee7]

I don't have enough detail yet.

What further details do you need?

I'm guessing you will need to go around the periphery.

there are holes in the floor of the rv under breaker and in the passthrough storage where the wires are currently routed under the rv within an enclosed underbelly. I am going to route any new wires through the same channel. It only drops down about a foot and then across the 25-30ft from passthrough to breaker. so maximum length these wires will go is maybe 32 ft one way.

So the slide has a 30 amp fuse in the distribution panel but I don't see the jack.
That complicates things.

The jack is directly connected to the battery. see attached pictures. I was planning to connect the 12v output of the dc2dc converter right where the battery is connected to everything now in the pictures.

 

[John Frum]

What further details do you need?

Is the breakaway system powered by that 12 volt battery?

there are holes in the floor of the rv under breaker

What breaker?

I am going to route any new wires through the same channel. It only drops down about a foot and then across the 25-30ft from passthrough to breaker. so maximum length these wires will go is maybe 32 ft one way.

Cool, so 64 feet round trip.
So 40 amps over 64 foot round trip at 12 volts.
To get below 3% voltage drop at the dc distribution panel you would need 1 awg.
1 awg can be hard to find so you may have to source 1/0 awg.
Copper is expensive.

The jack is directly connected to the battery. see attached pictures. I was planning to connect the 12v output of the dc2dc converter right where the battery is connected to everything now in the pictures.

The surge to start the motor on the jack could easily be 3x the rated draw.
What is the rated draw and locked rotor amps for that jack.

 

[JonBartee7]

Is the breakaway system powered by that 12 volt battery?

yes it is

What breaker?

I'm saying that the wiring to/from the breaker box (ac and dc distribution panel) is routed under the rv and there is a hole in the floor of the rv under the cabinet where the breaker box is which I will be using to route wires. Wires from the battery-> dc distribution are not run through the walls.

Cool, so 64 feet round trip.
So 40 amps over 64 foot round trip at 12 volts.
To get below 3% voltage drop at the dc distribution panel you would need 1 awg.
1 awg can be hard to find so you may have to source 1/0 awg.
Copper is expensive.

well if I can remove the ac2dc converter and put the dc2dc converter right under the breaker box, then it would be 24 volts across that distance.
Could I maybe just get a second dc2dc converter to run directly from the batteries to the spot where the hitch jack and all that is connected? I know you don't trust the cheap converters much but if I got a good one for the dc distribution panel and one of the cheap ones which would only be really for the breakaway and jack would that work?

 

[John Frum]

yes it is

The breakaway system needs power too.

well if I can remove the ac2dc converter and put the dc2dc converter right under the breaker box, then it would be 24 volts across that distance.

Then the math indicates 6 awg.

Could I maybe just get a second dc2dc converter to run directly from the batteries to the spot where the hitch jack and all that is connected?

Depends on the continuous draw in amps and the locked rotor amps for the jack?
Can this be manually actuated?
I think some folks just use a cordless drill for this.

I know you don't trust the cheap converters much but if I got a good one for the dc distribution panel and one of the cheap ones which would only be really for the breakaway and jack would that work?

See previous inline reply ^ .

 

[John Frum]

Just to make the scale and proportion clear

For 64 feet round trip

12 volts 40 amps   =  1 awg 2.72% drop
24 volts 25 amps   =  6 awg 2.71% drop
48 volts 12.5 amps = 12 awg 2.75% drop

 

[JonBartee7]

Depends on the continuous draw in amps and the locked rotor amps for the jack?
Can this be manually actuated?
I think some folks just use a cordless drill for this.

Power Tongue Jack | Lippert Customer Care Center

support.lci1.com

Says 30 amp rating but I don't see anything about continuous or locked rotor amps.
No it cannot be used with a drill manually, electric only.

 

[John Frum]

Power Tongue Jack | Lippert Customer Care Center

support.lci1.com

Says 30 amp rating but I don't see anything about continuous or locked rotor amps.
No it cannot be used with a drill manually, electric only.

The doco says it has a manual override.

https://lci-support-doc.s3.amazonaws.com/manuals/leveling-and-stabilization/ccd_0002172.pdf

Maybe you can contact the manufacturer for the LRA and whether running it from a converter is a supported useage model.
"FuseThe Power Tongue Jack is provided with a 30A ATO-type in-line fuse and will need to be replaced if it blows. The battery must be fully charged prior to operating the Power Tongue Jack. Low voltage from the battery will cause the fuse to blow prematurely" -- https://lci-support-doc.s3.amazonaws.com/manuals/leveling-and-stabilization/ccd-0004287-en-fr-es.pdf

 

[JonBartee7]

The doco says it has a manual override.

just went outside and checked and never noticed that little plug on top lol guess it does have manual override. I would still need power to the breakaway cable though and if I have to route power to that, I'd like to have power to the tongue jack as well.

Maybe you can contact the manufacturer for the LRA and whether running it from a converter is a supported useage model.

opened a case with their customer service, so I will probably not get a response on that until Tuesday because of memorial day.

So in terms of converters, I guess my best bet is the victron one since most other stuff I'm seeing isn't above the 55A rating that the ac2dc converter is.

https://www.amazon.com/dp/B01BF5BQLA?ref_=cm_sw_r_cp_ud_dp_NA2DBJK5ZW9JNYA2P2GJ

I noticed that it says it can be used as a battery charger too, "The adjustable output can be used as a battery charger"
Could I get like a 50ah 12v battery and connect the dc2dc converter to the battery to charge it via the 24v battery bank, then directly connect the 12v battery to where it is connected now? for the tongue jack and breakaway

 

[JonBartee7]

So like how I'm seeing it in my head is I could keep the dc2dc converter on the side of the whole system, run the larger gauge wire across the rv to the distribution panel, and substitute a washer on the 12v output of the conv with a ring terminal going to a smaller gauge wire being run to the 12v battery.

 

[John Frum]

Here is an idea.
Temporarily remove remove the 12 volt battery
and see if the jack will run off the ac2dc converter.
That will give us an idea how much converter you need to run the battery.
If the dc2dc converter can run the jack then it can run the breakaway system as well.

So like how I'm seeing it in my head is I could keep the dc2dc converter on the side of the whole system, run the larger gauge wire across the rv to the distribution panel, and substitute a washer on the 12v output of the conv with a ring terminal going to a smaller gauge wire being run to the 12v battery.

Not parsing ^