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24V diagram review for travel trailer please

acoleman43

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Aug 27, 2021
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I have a travel trailer I would like to be fitted with some solar. This is my first solar install so it would be nice to get more expert advice.

The end goal is 1600W (eight 200W panels) with two 200AH 24V batteries. Daily consumption is expected to be about 3000W per day.

We currently have an onboard 4000W generator. "Shore" power is 30 amp. I would like to place an automatic transfer switch between the generator and shore power.

I would like to have the AC out 2 from the Multiplus powering another 30 amp outlet. The thought is that others can plug into this outlet to use the generator if needed.

I am also planning to have a 24V DC panel for some additional things.

Before I start sizing wires, fuses, etc but would like some honest critique of my thoughts.

I hope this all makes sense. Thank you in advance for you time.

Equipment I am looking at:
-Big Battery 202AH 24V batteries (2)
-Victron Lynx Shunt
-Victron Lynx Distributor
-Victron Multiplus 24/3000/70
-(8) RIch 200W 24V solar panels OR (8) Hightec 200W 12V solar panels. 4 pair of series panels in parallel.
-Victron MPPT 150-100 solar charge controller (I found one for 30% off so already bought it)
-Victron Orion 24/12-70
-Victron Cerbo GX
-Victron GX Touch 50

Prelim diagram.jpg
 
I would like to have the AC out 2 from the Multiplus powering another 30 amp outlet. The thought is that others can plug into this outlet to use the generator if needed.
that is a cool idea - I was thinking about using my RV-solar system as backup "generator" for my house, that would enable this functionality.

Equipment I am looking at:
-Big Battery 202AH 24V batteries (2)
I'm not sure if I would use a big Battery in a high vibration environment as an RV - only if you can mount them with the cells inside facing in the right direction. Got that opinion from the teardown videos and case design. I couldn't care less for service-ability of a battery. Because 5 years from now you don't get parts anyhow.
The end goal is 1600W (eight 200W panels)
I'm planning a similar system size and looking into 400w panels - cheaper per watt and less roof penetrations - it always depends on the roof layout - just throwing out the idea -

so my RV will get 3-4x (435w to be exact) large panels.
I would like to place an automatic transfer switch between the generator and shore power.
nice to have but not necessary, - an AutoStart function for the generator - so that your Multiplus can start the generator when batteries are running low would be higher on my wishlist

Otherwise - good system design - I don't see something fundamental wrong with it. Just would use different colors for 24V and 12V when you go further and size your wiring.
What are your plans for the 24V Auxiliary Panel?
 
that is a cool idea - I was thinking about using my RV-solar system as backup "generator" for my house, that would enable this functionality.
That's "stage 2". I would like to use the solar/generator on the trailer as backup for priority appliances (fridge, freezer)

I'm not sure if I would use a big Battery in a high vibration environment as an RV - only if you can mount them with the cells inside facing in the right direction. Got that opinion from the teardown videos and case design. I couldn't care less for service-ability of a battery. Because 5 years from now you don't get parts anyhow.
Something I thought about...but didn't want to think about. This decision was based on price. Maybe I can find some vibration isolators under the batteries. I plan to mount the batteries on their side or back.

I'm planning a similar system size and looking into 400w panels - cheaper per watt and less roof penetrations - it always depends on the roof layout - just throwing out the idea -
The 200W panels fit well on the roof. I did try 300W panels but can fit only 4. I haven't looked at 400W panels....that could be a good option.

nice to have but not necessary, - an AutoStart function for the generator - so that your Multiplus can start the generator when batteries are running low would be higher on my wishlist

What are your plans for the 24V Auxiliary Panel?
That's not a bad idea. Something to consider.

The 24V aux panel will be for things outside the normal RV stuff. Onboard compressor, aux water pump, etc.. I may drop it down to 12V as well-not sure yet.


Thanks for your input. I really appreciate your time.
 
Something I thought about...but didn't want to think about. This decision was based on price. Maybe I can find some vibration isolators under the batteries. I plan to mount the batteries on their side or back.
you already bought them? Amperetime / Chins battery are similar/cheaper and good quality only the low temp cutoff missing. (you can add a sensor to the Multiplus - way better solution then disabling the BMS)

That's "stage 2". I would like to use the solar/generator on the trailer as backup for priority appliances (fridge, freezer)
same here, Fridge/ freezer, router, some lights, Window A/C or Mini Split for the main house.

I'm in Florida and our power goes out all the time. Would be a waste to have two sets of batteries - I rather have a very large bank in the RV.
When we are away with the RV - I couldn't care less if my home has no power.
 
Chassis bond should be on the system side of the shunt, luckily the lynx distributor has a dedicated grounding point.
The Victron Orion is a non-isolated converter so both black wires go to the same lug.
No wire guage, fuse size or lug diameter are annotated, might be worth doing.
 
you already bought them? Amperetime / Chins battery are similar/cheaper and good quality only the low temp cutoff missing. (you can add a sensor to the Multiplus - way better solution then disabling the BMS)
No, I haven't bought them yet. The only purchase so far is the Victron150-100 solar charge controller. It was $200 off....cheaper than the 150-70 and 150-85 so I didn't pass on the opportunity, plus it gave me more flexibility with solar array setup.

same here, Fridge/ freezer, router, some lights, Window A/C or Mini Split for the main house.

I'm in Florida and our power goes out all the time. Would be a waste to have two sets of batteries - I rather have a very large bank in the RV.
When we are away with the RV - I couldn't care less if my home has no power.
At first I thought I was strange...glad to see somebody else thinking about that. I live in Texas where summers are extra toasty and appliances don't maintain temperature well if they don't have power.



I guess I need to start sizing wires/fuses. Where would you place fuses?
 
Chassis bond should be on the system side of the shunt, luckily the lynx distributor has a dedicated grounding point.
The Victron Orion is a non-isolated converter so both black wires go to the same lug.
No wire guage, fuse size or lug diameter are annotated, might be worth doing.
Thank you for the advice!

I haven't sized wire yet because I wanted to make sure the system was sound first :)
 
2/0 wire from the batteries to the un-fused position on the busbar
250 amp fuse as close as possible to the positive terminal of the batteries.

2/0 wire from the lynx to the inverter/charger
250 amp fuse on busbar

4 awg wire from lynx to orion converter
125 amp fuse on busbar

4 awg wire from orion to dc distribution center
125 amp fuse on busbar

4 awg from busbar to solar charge controller
125 amp fuse on busbar

I consolidated wire and fuse sizes to keep the bom simple and reduce the number of required spares.
 
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2/0 wire from the batteries to the un-fused position on the busbar
250 amp fuse as close as possible to the positive terminal of the batteries.
Fuse would be in the Lynx Shunt, correct? The Lynx shunt/distributor will be within 24" of the batteries, is that sufficient?

2/0 wire from the lynx to the inverter/charger
250 amp fuse on busbar
Fuse would be inside Lynx Distributor, correct?

4 awg wire from lynx to orion converter
125 amp fuse on busbar
Fuse would be inside Lynx Distributor, correct?

4 awg wire from orion to dc distribution center
125 amp fuse on busbar
Fuse would be in-line before existing busbar, correct?

4 awg from busbar to solar charge controller
125 amp fuse on busbar
Fuse would be inside Lynx Distributor, correct?


I really appreciate your time on this. Thank you!
 
Fuse would be in the Lynx Shunt, correct? The Lynx shunt/distributor will be within 24" of the batteries, is that sufficient?


Fuse would be inside Lynx Distributor, correct?


Fuse would be inside Lynx Distributor, correct?


Fuse would be in-line before existing busbar, correct?


Fuse would be inside Lynx Distributor, correct?


I really appreciate your time on this. Thank you!
The master fuse(battery fuse) goes as close as possible to the battery positive terminal to minimize the chance of an upstream short.
Correct the wire from the batteries lands on the lynx shunt.

The fuse for the inverter circuit is part of the lynx.

The fuse for the dc distro panel is part of the lynx

The fuse for the orion circuit is part of the lynx.

Yes the fuse between the orion and the legacy busbar is in-line.

The fuse for the solar charge controller is part of the lynx.
 
2/0 wire from the batteries to the un-fused position on the busbar
250 amp fuse as close as possible to the positive terminal of the batteries.

2/0 wire from the lynx to the inverter/charger
250 amp fuse on busbar

4 awg wire from lynx to orion converter
125 amp fuse on busbar

4 awg wire from orion to dc distribution center
125 amp fuse on busbar

4 awg from busbar to solar charge controller
125 amp fuse on busbar

I consolidated wire and fuse sizes to keep the bom simple and reduce the number of required spares.
For 24v/3000w inverter I calculated 1/0 wire. How did you calculate 2/0? Not saying your wrong, I just want to learn correct way. I'm a novice
 
For 24v/3000w inverter I calculated 1/0 wire. How did you calculate 2/0? Not saying your wrong, I just want to learn correct way. I'm a novice
My eyes are too tired to read back through the whole thread so I just had a quick look

-Victron Multiplus 24/3000/70
-Victron Orion 24/12-70

From the manual the inverter gets 50mm2 which is roughly equivalent to 1/0awg.
When we add the Orion and considering we don't know the wire lengths I bump the main circuit to 2/0 awg.
Since we bump the main wire to 2/0 awg I bump the inverter wire to 2/0 to consolidate the bill of materials.
Common fuses and common wire gauge.
I would change the spec to 300 amp fuses as larger fuses have lower resistance.

When you bust a cat house you take the piano player too.
 
you already bought them? Amperetime / Chins battery are similar/cheaper and good quality only the low temp cutoff missing. (you can add a sensor to the Multiplus - way better solution then disabling the BMS)


same here, Fridge/ freezer, router, some lights, Window A/C or Mini Split for the main house.

I'm in Florida and our power goes out all the time. Would be a waste to have two sets of batteries - I rather have a very large bank in the RV.
When we are away with the RV - I couldn't care less if my home has no power.
I just received my Chins batteries ahead of time. I got 4-24-volt 200ah for 15% off from the Amazon price each; free shipping delivered to my door.
 
I'm doing the same setup on my 28-foot class C, but I don't have the bucks for the Victron stuff, maybe charge controller, but I will see what panels cost me. I went with 4 Chins 12-volt 200ah that will be configured into a 2s2p for 24-volts at 400ah. I also received my Giandel 24-volt 4kw inverter today. Now I have something to play with. :cool:
 
For 24v/3000w inverter I calculated 1/0 wire. How did you calculate 2/0? Not saying your wrong, I just want to learn correct way. I'm a novice
Victron rates there stuff in volt amps...
3000 volt amps * .8 power factor = 2400 watts
2400 watts * 1.5 premium low frequency fudge factor = 3600 fudge watts
3600 fudge watts / 24 volts low cutoff = 150 service amps
150 service amps / .8 fuse headroom = 187.5 fault amps
By the book you could go as low as 2 awg with a 200 amp fuse.
But Victron's manual indicates 1/0 awg so 1/0 awg minimum it is.
Pure copper 1/0 awg wire with 105c rated insulation is good for a little over 250 amps so we would use a 250 amp fuse.
 
150 service amps / .8 fuse headroom = 187.5 fault amps
By the book you could go as low as 2 awg with a 200 amp fuse.
You add a double safety factor there. Fudge Factor + Fuse Headroom.
I'm running my 3000W Growatt with 2 awg wire on a 24V CHINS.

And that thing puts out true 3000w. I can run my 13500BTU A/C unit (1200w running) and a Microwave - at the same time. Sits right a 95% capacity - just shy of 3000W. It even survives the surge of both appliances.

At those 3000W - the battery voltage sits around 25-26V and I'm pulling roughly 120A.
The 2 gauge wire is not even getting warm and a 4 FT run.

Pure copper 1/0 awg wire with 105c rated insulation is good for a little over 250 amps so we would use a 250 amp fuse.
your fuse should not only protect the wiring but also the connected devices. When the inverter is designed to 150A - installing a 250A - might melt it internally / burning - instead of blowing the fuse in the case of a short - go with the fuse size the manufacturer recommends

You can use the larger wire if you want to reduce voltage drop- you can have 0/1 gauge with a 25A fuse. But don't go oversize with the fuse.
 
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