Design review please

[captainrivet]

Hi all,
so I finally finished the installation wiring diagram of my 840AH 12V LIthium house bank on my catamaran.
Could you please review the diagram. I use the Electrodacus BMS which controls everything via remote on/off and has full control over the load/charge on cell level. its also current free means upgrading system is no problem,, Thats why you don't find any big chunky and expensive high current relays or SSRs.

Well the cat doesn't even have a main fuse yet, so while getting the lithium installed I also clean up the french/UK/spain "install cooperation" called newbee rats nest....
All fuses 100A and above are NH 0-2 fuses and main fuse is a chunky 630A NH3 fuse which also work as high current off/on switch, just pull or insert the fuse with thr puller tool (located fixed in the fuse area)...cheap,reliable, sturdy, longlivity and made for the high current constant use. The holders are quite expensive but you can get them on ebay for a steal, just bougt 5xNh0 and 8x NH1 holder plus a 630A NH3 fuse for 60Euro...never used spares from a factory that got knocked down...you get one class T fuse holder for that...

The 230V diagram is not included, I need to finish it first but that is mainly legacy system with a small change in a different main 230V cable upgraded from 3x2,5mm to 3x6mm to be able to handle 6kw and change main 25A breaker to 32A version and a seperate 16A plug+fuse just for the induction cooktop.
The catamaran is setup to be fully self sufficent and even when I am in a marina I don't plan to hook up to shorepower/grid. The gridcharger is actually planned as backup to charge via a portable Honda gasoline generator that is then simply pluged into the shorepower connector. So i am ok with flippng a manual switch to switch to real grid and adjusting the power assist level accordingly if I plug into shorepower. thats why I chose the multiplus and not the 1000Euro more expensive Quattro which could handle that automatically, hardly ever need it and if manual operation is ok.

I am running a full electric galley on my catamaran which is the main power draw but only for short periods of time. This consist of a 3500W 3 burner Bartscher 3512 commercial grade induction cooktop and a Panasonic Mircowave/Convection oven/Steamer combo with 1100-1400W. Mostly only 2 burner of the cooktop will be used, so thats max 2200W draw= 200A which the victron multiplus can handle alone.
But sometimes I will use all 2 or 3 burners plus the convection oven and then I need 2500W+1400W=4kw so 350-380A for maybe 15min max and then I will boost the multiplus via its power assist function and use my legacy 3500W HF inverter as fake grid. This supplies 10A or 2200W (adjustable 4-16A, but 10A will be standard) and multiplus regonized AC input and its transfer switch routes the 10A AC 230V through and the rest the Victron will deliver via power assist what is needed above 10A or 2300W. To prevent the multiplus from using part of the fake grid 230V its charger is shut off via Temp input automatically when the Edecoa inverter is on and delivering 230V.
Battery pack is3p4S 12V 840AH measured capacity and bulid with 10mmx20mm thick tinned plated cooper busbars to be able to deliver continous 500A. Means I can fire up Cooktop and stove to max 3500+1400W=4,9kw and still have some margin to 500A.
both inverter togehter can deliver 3500W+2400W=5,9kw if needed.

Major charge source are 3 Bifacial solar panels with each 445W=1335W each panel connected to its own Victron 50/100 Mppt.
DC-to-DC alternator setup: ENgines are new D2-50F with the new 115A mitsubishi alternators, which deliver around 60A cont.
THe legacy charging system works that if any of the 2 engnies running that thy Victron Cytrix battery combiner combines both FLA banks and charges it.
So I use 2x 30A Victron DC-To-DC charger in parallel connected to the STB engine room busbar. So if each of the engine=one alternator runs, the one alternator is maxed out as one can do 60A cont. savely. If I use engine longer is mainly 1 engine that runs. if both engines run its still the 60A charge, loose some charge cpapbility but thats ok and won't happen often. Main goal is to have the alternator running savely and as cheap as possible when motoring and maxing one alternator out if one is running longer periods eg motorsailing...

Thank you.
Christian

 

[captainrivet]

At the moment I keep the quite new 2x90AH FLA Starter BB and STB 300AH FLA Hybrid house/starter till I have some experience with the Lifepo4 install and system runs stable. Then I will delete all FLA except of one 90AH FLA starter per engine to offset the 70kg+ weight gain per hull for the upgrade from 3 Zylinder 20hp Volvo 2020 to the 4 cylinder 50hp D2-50F engine and the bigger saildrives. Lifepo4 bank is 60kg installed midships now, 120kg FLA above the engines in the rear engine rooms will be deleted then so balance is as new from factory but with upgrade overpowered engines (former owner done that swap and sold it with 19h on both new engines).

 

[captainrivet]

No one any thoughts?

 

[GXMnow]

I took a quick look. That seems overly complex. It will take me a while to figure out what all is really needed. You have triple power systems in some places. I get wanting a backup, but this just seems overkill. Staying at 12 volt does make for a lot of current. Do you know what your loads are in actual use?

 

[captainrivet]

I took a quick look. That seems overly complex. It will take me a while to figure out what all is really needed. You have triple power systems in some places. I get wanting a backup, but this just seems overkill. Staying at 12 volt does make for a lot of current. Do you know what your loads are in actual use?

What’s overcomplex?
It’s a cat with 2 engine rooms, 2 inverters and 3 MPPT. 3 MPPT instead one big because the bifacial solar deliver 15% more then on one big plus redundancies. That’s also main charge source…
Yes I am pulling around 250A in normal operation cooking but occasionally 450A. I am just splitting the big loads close to battery and run the big loads separately so each carries less current.
All is beefy and speced for 600A cont. so small voltage drop and my big loads are within 50cm of the bank, so it doesn‘t matter if 12 or 24V.

 

[Kruncher]

I think it looks good. Fair amount of redundancy (emergency starting ...) & well thought out into the design.

How are you monitoring? Victron is pretty good with this... might be in the schematics.

I have no idea of the solar arrays, but for the CB spec those to 80% or your expected max current transfer (at least that's what I was recommended when I installed my Tesla wall charger).

Cheers

 

[captainrivet]

I think it looks good. Fair amount of redundancy (emergency starting ...) & well thought out into the design.

How are you monitoring? Victron is pretty good with this... might be in the schematics.

I have no idea of the solar arrays, but for the CB spec those to 80% or your expected max current transfer (at least that's what I was recommended when I installed my Tesla wall charger).

Cheers

Monitoring with Electrodacus BMS via wifi and all victron equipment via BT Control App too.
evaluating the Victron cerbo on a rasbery Pi at the Moment.

 

[WYtreasure]

Are these switches approved for use under load?


"...never used spares from a factory that got knocked down...you get one class T fuse holder for that..."
I don't really understand what you were trying to say here, but people use Class-T fuses for their speed.

Lifepo4 batteries like to be charged and balanced before being connected. I do not know how you are connecting your Lifepo4 batteries into a bank.

 

[captainrivet]

Are these switches approved for use under load? View attachment 88224


"...never used spares from a factory that got knocked down...you get one class T fuse holder for that..."
I don't really understand what you were trying to say here, but people use Class-T fuses for their speed.

Lifepo4 batteries like to be charged and balanced before being connected. I do not know how you are connecting your Lifepo4 batteries into a bank.

Yes, all switches BlueSea exactly speced for the use.

3p4S connected in 6 cells in 2 rows side by side with 10mmx20mm tinned copper busbars, made from 12 Lishen 272AH grade A cells matched from factory. every cell individually charged and top balanced, then all 12 cells put in parallel and again top balanced after sitting for 48h hours at 3,3V charged To 3,6V. Then the whole pack assembled, discharged to 2,6V with 0.3C and charged full again 3,55V to give the BMS a reference charge.

yes Class T fuses are super fast as with their physical size they can only handle the speced current and little more.
class T fuses are perfect for HF inverter as they can protect them quick from deadly high surge overload but work fine till rated continuous wattage of your HF inverter. They won‘t work well for a LF inverter or expensive HF or Hybrid inverters like Victron, Samlex etc because the class T fuse need to be overspeced to allow the high surge capabilities these inverter can do but then cannot protect the continuous overload.

Also as main battery fuse for a LifePo4 house bank on a boat a class T fuse is one of the worst fuse types you can chose because fast acting in all cases is not what you want and need here:
what’s the job of a main battery fuse?
protect the battery from a short circuit, protect the battery from continuous and peak overloads, protect the installation from an internal defect of the cells but allow the short high current delivery possibility of livepo4 to act as emergency starter battery or deal with short high surge inverter loads too and if additionally possible protect the main battery cable (2x big fuses are a lot voltage drop, so you want one fuse that can do this job too).

so we take a typical 300AH 12V LifePo4 house bank, a 3kw inverter and a 30hp inboard engine and a 1000W windlass.
to protect the 300AH bank from continuous overload = more then 1C=300A a superfast fuse need to be 300A-350A but this already blocks the short surge capability of 2C = 600A this bank can do because the fuse will blow at 350A-400A.


Even worse on that boat you have a starter on the 30hp engine, windlass and other loads with high but short surge. A LifePo4 can handle short surges 2x or even 4x it’s rated capacity without damage. In case your starter dies, the lifepo4 house Must be able to start the engine. the 30hp engine has typically a 2000W starter that will have a startup surge of 600-800A for some milliseconds and then need 150-250A for 2-3 seconds. The windlass the same 600A surge and then 100A for 10sec.

A superfast fuse will blow at 350-400A already after a millisecond but your 300AH LifePo4 bank can easily deliver 800A for some seconds and need to in this case. So to enable this the class T would need to be overspeced for 800A, so it’s not blowing when you use it as emergency starter. But then it cannot fulfill its overload protection because a 300AH LifePo4 can only deliver 1C=300A permanent and up to 20s 2C=600A permanent but the superfast fuse only blows at 800A.

if you take an NH fuse it acts fast in short circuit of 5-10x amps of it’s rating but slow acting as overload and cable protection, exactly what you want and need:
in above case a 250A NH does the job perfectly: it allows a short surge of 4x its rating=1000A so it starts the engine even under worst condition without blowing. At 250A continous use it still works without getting more then handwarm, short 5-10s surges to 350-500A from the 3000W inverter pulling an inductive load like an induction cooktop also works without blowing the fuse and your cells/bank can handle this. But pulling 500A for 1min will blow the fuse without damaging the cells or if a cell shorts under high load causing a 3000A spike it blows instantly without the 95sqmm or 2x70sqmm cable getting damaged.
additionally NH fuses are constructed that they can dispute themself the heat they produce and not rely on the surroundings= busbar or cable heats up acting as heat sink like Megafuse or ANL need to cool the fuse. Their loss ratings=heat=resistance are given at full rated amps in 24x7x365 days use compared to eg class T which are rated at 75% of rated amps after 10min of use. Put class T at 90% of its rating and they get fast very hot and with this the losses=voltage drop rises…welcome to the devil cycle. Not happening with NH fuses.

NH fuses are cheap 5-50Euro fo GG or GL type but you can get for fraction of the price used as I said above eg from factories that have them as spares and close down. Paid 30 Euro for 25 fuses, enough for installation and several spares.
and you can use them used as they are made for super harsh environment and public grid with permanent quality controls. Yes they need more space then a class T because the need to handle more amps for the same rating.

 

[WYtreasure]

Yes, all switches BlueSea exactly speced for the use.

Damn good info Captain. That will be the last time I preach to a mariner about a Class-T fuse. I think my microwave will be fine with one though.