Can someone help me finalize my system layout?

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Peter asked Nov 26, '21

Can someone help me finalize my system layout?

I bought an 1600w off-grid kit built on Victron components. I was told after I bought it that it was designed for an RV installation or cabin. And is designed to be set up for 24v. The company does not have any experience connecting to boat systems. Parts that came with the kit - 2 lynx distribution blocks, 1 MPPT 150/70, cerbo gx, lynx smart dongle, 2 multiplus 24/3000/70-50, 2 orion dc-dc, and a lot of fuses and circuit breakers.

I am using 4 LG 425w panels and 4 200a 12v dakota lithium batteries.

I assume I can remove all the original charging and inverter parts. And wire the shore power directly to the multiplus, then the ac and dc outputs would go to the boats ac and dc distribution blocks...?

I dont know if using it at 24v with 2 multiplus units is overkill. Or just set it up as 12v and use 1 multiplus. Any help would be appreciated

Pete
Knot Tide Down

MPPT SmartSolar system design

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kevgermany answered · Nov 27, 2021 at 04:47 AM

Make sure you add a galvanic isolator between shore power and boat.

Decision on the multiplus units is how much AC do you need at any one time. You could install both. Only switch one on. Check the manual if you want two, the AC outputs must be in phase if they share output circuitry.

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Peter commented · Nov 27, 2021 at 03:29 PM

Thanks. Yeah I dont think I will need both Multiplus units, since the only AC powered things are the water heater and the A/C. I have them both but would it be worth it to install both or return the second one? Then if needed buy it then.

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JohnC answered · Nov 27, 2021 at 11:47 AM

Hi @TVP Auto Raleigh Clear Bra Specialists

That diagram looks suspiciously like a 120V split phase system. One Multi per phase, and you may want both. Regardless, if they're 24V units, they remain 24V, so will your batts.

Boats aren't much different to RV's, maybe a little more care with earthing to avoid electrolysis. This is a good general reference.. https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN.pdf

If you plan to diy it you have a lot to learn, but if you don't want to do that a Victron man could handle a boat installation just the same as an RV.

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Peter commented · Nov 27, 2021 at 03:33 PM

I do plan on doing the install myself. I need to learn all of it since I will be using the boat for long trips. As for thr 24v, I could exchange the 24v units for 12v units. And just use 1 multiplus as well. The main issue Im seeing is that I would have to separate the 12v starter battery/alternator from the 24v house battery. Is the efficiency of a 24v system worth not being able to connect those systems?

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kevgermany ♦♦ Peter commented · Nov 27, 2021 at 05:43 PM

The mixed system isn't really a hassle. Stick in an Orion 24/12 isolated smart charger, this will charge your starter batteries perfectly.

There are a few advantages of 24V. Mostly lower current, thus lighter cabling, less power loss, less voltage drop over connections. But probably not worth it if you only have low power consumption. Many boat type USB charger sockets and led lights can run on 24V. Also some fridges. But you do need to keep the systems separate and clearly marked.

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Peter kevgermany ♦♦ commented · Nov 28, 2021 at 01:03 AM

Thanks! Yeah I think Ill go that route. Seems like it will work out ok. I am not sure Ill need both multiplus units. The water heater and air conditioning are the only things that will run more constantly. Other appliances like a blender probably will only be short.

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Answer 1 · 2021-11-27T15:35:13Z

seb71 answered · Nov 27, 2021 at 03:35 PM

It's not a good strategy to buy random components and after that wonder how they work together and if they are fit for the intended purpose.

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Peter commented · Nov 28, 2021 at 01:06 AM

That wasnt the plan. I was told initially that the system would work for my purpose. They are not random components, but just a system that may need some more planning. Do you have anything constructive to add?

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seb71 Peter commented · Nov 28, 2021 at 08:05 AM

If you can, return everything and start from a plan.

"It's for a boat" is not a plan.

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Peter seb71 commented · Nov 28, 2021 at 03:43 PM

Agree. I sent the supplier a spreadsheet with all the components and loads that I was planning on using. And the connections with the boat. And was told they would provide me with an initial schematic once the purchase was complete. That is what I included in the first post. I understand Ive jumped into this trusting the supplier, and I am learning rapidly the correct info.

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seb71 Peter commented · Nov 28, 2021 at 04:55 PM

You should really consider switching to a 48V system (48V battery), if you will really use that kind of power (5-6kVA).

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Answer 2 · 2021-11-28T03:13:33Z

Paul B answered · Nov 28, 2021 at 03:13 AM

Keep in mind that the batteries you are proposing - although good batteries - have a internal BMS - so if one set goes down you will not know that it has unless you check them regulary. also they are usually MAX current limited for load and charge as well

I would consider batteries that have a external BMS control like the Victron Smart battery

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Answer 3 · 2021-11-28T09:50:38Z

kevgermany answered · Nov 28, 2021 at 09:50 AM

Just wondering how much power A/C and water heater draw, also any other small AC loads. Can add up quickly. Check the rating for your multiplus. It's temp dependant. Will also handle short overload periods.

If you're close to the limit, a single 5KW unit might be better.

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Peter commented · Nov 28, 2021 at 03:38 PM

Ok. I have that info in a spreadsheet that I sent to the supplier. I will reference and see, but that makes sense. I would rather stick with 1 5000 if thats the case.

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