Designing Victron System for Keystone RV Travel Trailer

[HRTKD]

Have you tested this?
I mean administratively open the discharge path on the bms.
isolate the panels from the scc to simulate night.
re-connect the panels to the scc to simulate daytime and see if the ssc will charge.
Many sccs need to see voltage on the bat side so that they can detect the system votlage before they will charge.

I didn't test it. I think Will did a video on it and that's what catapulted the Overkill Solar BMS to being as popular as it is.

 

[HRTKD]

the multiplus II GX doesn’t need all the cables and has the same functionality as the Cerbo to my understanding. It also runs venus os.

Oh, duh. Hence the GX in the name. That's good to know.

 

[SendIt]

Updated schematic with grounding and shunt removed:


Gonna sit on it a bit before purchasing anything. The trailer is currently in storage and I can't remember, but am pretty sure that the A/C components are grounded to the frame in multiple places. I found manufacturer instructions on how to do a g-n bond in my generator.

Thanks again for the input.

 

[John Frum]

Updated schematic with grounding and shunt removed:

The lynx should be bonded to the frame to give the 48 volt dc domain reference.

The trailer is currently in storage and I can't remember, but am pretty sure that the A/C components are grounded to the frame in multiple places.

That sounds wrong.
By A/C do you mean air conditioning or alternating current?
The alternating current domain for a system that is powered only via the shore power inlet should have only one reference to the chassis.
Typically that chassis reference is for both ac/dc sides of the distribution panel.
The dirt bond and neutral/ground bond are upstream from the pedestal.

I found manufacturer instructions on how to do a g-n bond in my generator.

Suggest you use a bonding plug so that the generator can be used in its default floating mode when not attached to the travel trailer.

https://www.amazon.com/Southwire-Company-LLC-44400-Generator/dp/B07F4R7BDL

 

[HRTKD]

@SendIt, do you have the generator prep package in your trailer? I'm not sure where I was going with that, but I do recall that if you have that package it can make this upgrade a bit easier.

 

[SendIt]

@SendIt, do you have the generator prep package in your trailer? I'm not sure where I was going with that, but I do recall that if you have that package it can make this upgrade a bit easier.

It is a stock 2017 Keystone Springdale. I have a mini generator so the plan is to just plug that into shore until I get the solar set up.

The most difficult part is running wires from where the batteries are going to the power distribution center. Going to have to drill holes in the floor and run a conduit under the trailer. I’ll post pictures if anyone is interested.

 

[SendIt]

The lynx should be bonded to the frame to give the 48 volt dc domain reference.

Got it

That sounds wrong.
By A/C do you mean air conditioning or alternating current?

Alternating current. I’m probably remembering wrong. The DC system is probably using a chassis return and I mixed it up… been a few weeks since I looked at it.

Suggest you use a bonding plug so that the generator

makes sense!

 

[John Frum]

It is a stock 2017 Keystone Springdale. I have a mini generator so the plan is to just plug that into shore until I get the solar set up.

The most difficult part is running wires from where the batteries are going to the power distribution center. Going to have to drill holes in the floor and run a conduit under the trailer. I’ll post pictures if anyone is interested.

Put the dc2dc converter near the dc distribution panel because voltage drop is less of an issue at 48 volts than 12 volts.

 

[SendIt]

Put the dc2dc converter near the dc distribution panel because voltage drop is less of an issue at 48 volts than 12 volts.

Yup, planning on sticking it inside the distribution panel to the same bracket where the stock converter was.

 

[John Frum]

Yup, planning on sticking it inside the distribution panel to the same bracket where the stock converter was.

Where do you plan to put the core of the system?

 

[SendIt]

Where do you plan to put the core of the system?

I think I can fit everything under one of the dinette seats, which is just across the isle from the power panel.

It’s maybe a 10-12’ run after going through insulation and along the belly of the camper.

Plan is to disconnect the very long shore plug from the panel, drill holes in the floor, and run it under the trailer.

I’ll also run a 48v + and -, a 120v pos, neutral, and ground, and the data cable that goes from the cerbo to the DC-DC converter I’m installing in the panel.

All the other wire runs will be much shorter as it’s all fitting in a pretty small space under the seat.

 

[SendIt]

After hearing about this black friday sale. I'm considering dropping to 24 V and buying 8 x 280A cells to save myself ~$650 and get 1.9 kwh more capacity...

Looking at the wire/fuse sizes @John Frum selected, I don't think I'll need to bump them up at all since it looks like there is a lot of safety factor.

 

[John Frum]

After hearing about this black friday sale. I'm considering dropping to 24 V and buying 8 x 280A cells to save myself ~$650 and get 1.9 kwh more capacity...

Looking at the wire/fuse sizes @John Frum selected, I don't think I'll need to bump them up at all since it looks like there is a lot of safety factor.

View attachment 122001

You will need a bigger bms and a different dc2dc converter.
Suggest a non-isolated 24->12 dc2dc converter.

 

[MisterSandals]

Suggest a non-isolated 24->12 dc2dc converter.

Why non-isolated? I always wondered about the use case for this model. Just trying to learn something.

 

[John Frum]

Victron wants double 1/0 awg for > 5 meters round trip.
Which is a bit silly.
Are you planning to buy the wire today as well?

Why non-isolated? I always wondered about the use case for this model. Just trying to learn something.

They are cheaper and use a bit less wire.
They are also available in much higher amperage.
It does require special consideration with the tow cable though.

 

[John Frum]

Suggest you bump up the battery circuit to 2/0 and a 300 amp class-t fuse.
The inverter circuit should be 2/0 and 250 amp mega fuse.
Suggest the Orion 24/12-70 non-isolated converter.

 

[SendIt]

You will need a bigger bms and a different dc2dc converter.

Any other brands you recommend?

[why non-isolated]
They are cheaper and use a bit less wire.

Wow, yeah they are: https://icmontana.com/products/orion-dc-dc-converters-non-isolated-high-power?variant=42832984441062

Are you planning to buy the wire today as well?

No, I'll pick that up from the local distributor who's selling me the victron equipment. I can probably get them to check over the plans as well since they sell pre-built systems. 1/0 is huge, but it's going to be a very short run, so at least it won't completely break the bank.

It does require special consideration with the tow cable though.

My plan is to disconnect the trailer aux power pin, so the vehicle electrical should be completely separate from the trailer.

Suggest you bump up the battery circuit to 2/0 and a 300 amp class-t fuse.
The inverter circuit should be 2/0 and 250 amp mega fuse.
Suggest the Orion 24/12-70 non-isolated converter.

Got it, thanks.

 

[John Frum]

Any other brands you recommend?

There is a jbd with a 200amp contactor.
I don't have any experience with it but it should work and should work with the equivalent cerbo integration I would think.

Wow, yeah they are: https://icmontana.com/products/orion-dc-dc-converters-non-isolated-high-power?variant=42832984441062

I think the integration with the cerbo for lvd and administrative disconnect will be different but functionally equivalent.https://icmontana.com/products/orion-dc-dc-converters-non-isolated-high-power?variant=42832984441062

1/0 is huge, but it's going to be a very short run, so at least it won't completely break the bank.

I'm suggesting 2/0 awg which is even bigger.
Just to keep Victron happy.
We don't won't any voltage sag when that inverter is surging to ~150% of its rating.

My plan is to disconnect the trailer aux power pin, so the vehicle electrical should be completely separate from the trailer.

Excellent.

 

[John Frum]

Since you will be using a non-isolated dc2dc converter the chassis bond in the ac/dc distribution panel should be removed.
That way there is only one path for a ground fault to chassis back to source.

 

[HRTKD]

No, I'll pick that up from the local distributor who's selling me the victron equipment. I can probably get them to check over the plans as well since they sell pre-built systems. 1/0 is huge, but it's going to be a very short run, so at least it won't completely break the bank.

Get welding cable. It's so much easier to work with. The typical cable you get from the big box stores is very stiff and difficult to work with if you ever need to bend it.