31.2Kw Victron LiFePO4 Split System Install

[Capdave360]

Originally Posted by CalmSeasQuest

Greetings all,

I'm in the process of upgrading the solar and electrical systems on my 2019 Fountain Pajot Saba. After extensive research, I've settled on a somewhat "atypical" design to overcome some single-point-of-failure concerns. I'm new to LFP systems and would greatly appreciate any comments or suggestions offered.

SV Ghost Electrical System Overview
In researching LFP designs I was troubled to learn that an entire battery bank can be shut down by the BMS due to problems with a single cell. If a single battery bank were used, this could result in the vessel going dark. This was not an acceptable outcome. Instead I chose a design that provides redundancy and fault tolerance with automated fail-overs should a battery bank shut down for any reason. To accomplish this, we split the AC and DC systems.

AC Systems
The AC side consists of 1000AH @ 24V Victron LFP driving 2 X 24V, 3Kw-230V and 2 X 24V, 3Kw-115V MultiPlus charger inverters. The bank is maintained by shore power or a 13.5Kw Genset through a 100 Amp Victron Autotransformer (to prevent leg imbalance) and 1850W of Solar. The system is sized to allow us to operate about 20K BTU of AirCons overnight and occasionally throughout the day (i.e. meal prep), sans GenSet. Plans exist for the addition of a 180AH 24V alternator should; based on real world use and performance it be needed. This bank is responsible for the following potential loads,

• 6 AirCon Units – 60K BTU (3 @ 12KBTU, 3 @ 8KBTU fitted with SoftStarts)
• A theoretical maximum of 12Kw of combined 115V/230V inverting
• 280 Amps of 24V battery charging (6720W)
• 12V House Bank Charging - DC/DC 24V/12V @ 60 Amps
• Watermaker - Aquabase YK3 180 L/H (Alternate power source – Genset Primary ~2000W)

24V Fault Tolerance and Fail-Over Rationale
Should the 24V bank encounter a low voltage/SOC condition, the GenSet is configured to auto-start and auto-stop based on pre-programmed values.
Should the BMS shut down the 24V bank for any reason, all critical systems, (Navigation, windless, lighting…) continue to operate off the 600AH 12V bank. Additionally, the GenSet can be started to maintain all AC systems.

DC Systems
The DC system consists of 600AH of 12V Victron LFP. The bank is maintained by 60 Amps of 24V/12V DC/DC charging and the 2 engine alternators fitted with Wakespeed WS500 external regulators. This bank drives,

• All critical vessel DC systems including navigation, communication, autopilot, windless and lighting

12V Fault Tolerance and Fail-Over Rationale
Should the 12V bank suffer a BMS shutdown or low SOC, a relay routes all 12V loads to the Starboard 200AH AGM start battery. The start/fail-over AGMS are charged via individual 24/12 DC/DC chargers. The starboard battery is also charged by the GenSet Alternator (the Starboard engine shares the start battery with the GenSet.) This can also be paralleled with the Port side 200AH start/fail-over battery if needed.

European Power (230V/50Hz) Solution
For shore power use when in locations using 230V/50Hz power, a manually activated system diverts 50Hz shore power only to the pair of 24V/230V MultiPlus charger inverters which charge all battery banks and provides pass-through to the AirCons and watermaker. The 24V-115V MultiPlus’s operate in inverter-only mode supplying 115V service to the vessel.

System Components
Wherever possible we prioritized Victron components as we had extensive Victron equipment already onboard and to maximize interoperability.

5 X Sunpower X22 370W Solar Panels = 1850W (we're working on ways to install additional solar)
5 X Victron SmartSolar MPPT 100/50
5 X Victron 200AH 24V Smart LiFePO4 = 24Kw
2 X Victron 300AH 12V Smart LiFePO4 = 7.2Kw
2 X Victron BMS300200000 VE.Bus BMS
2 X Victron MultiPlus 24V/3000W/70A-50 120V
2 X Victron MultiPlus 24V/3000W/70A-16 230V
1 X Victron Autotransformer 120/240 - 100A
2 X Victron Orion-Tr Smart 12/12-30A (360W) Isolated DC-DC charger (Paralleled 12V House bank)
2 X Victron Orion-Tr Smart 12/12-18 18A Isolated DC-DC Charger (Start/Fail-over)
2 X 200AH 12V AGM Start/Fail-Over batteries
2 X Wakespeed WS500 12V External Voltage Regulators
2 X Sterling Power Alternator Protection Device for 12v (AP12D)
1 X Genset Autostart Functionality (Onan 13.5Kw)
3 X MICRO AIR - ASY-364-X07 EasyStart 3 Ton
3 X MICRO AIR - ASY-364-X36-IP EasyStart 3 Ton
1 X Victron - BPP900450100 Cerbo GX
1 X Victron - BPP900455050 Cerbo Display
2 X Victron - LYN040102100 Lynx Shunt VE.Can
2 X Victron - LYN060102000 Lynx Distributor
XXX PACER - 4/0 AWG Black/Red Battery Cable (more feet then I care to count)
Numerous Blue Sea Systems, Merlin Gerin and E-T-A Fuses, Relays, Switches and Breakers
Battery Tables Created Using 80/20 Extruded Aluminum

There are a few areas yet to be determined such as monitoring. We currently use a Color Control GX and are adding a Cerbo GX with the GX Touch 50 controller. The hope is to transition all to the Cerbo, but it is unclear if it supports multiple BMS.

Thanks again for putting up with such a long post - I truly appreciate your time and any comments or suggestions.

This is really fun. It will probably more or less work, though not without some adjustments and some quirks. BTW I've used 24V 250A Electrodyne alternators - great machines.

All that said, if what you really wanted out of all this most of all is reliable 24/7 air conditioning, this is dramatic overkill. For a fraction of the mass, volume, and cost you could have double elastic mounted and double cocooned a generator, stripped the water off to keep the exhaust quiet, and it would be waaaaaaay less complex and waaaaaay more reliable. You probably could have done it twice - once each side - and still be under 50% of the cost. But it is a really fun experiment....

In the end you have to feed the aircons. The solar panels won't run 60KBTU regardless of how much you buffer with storage, and your system will have really significant efficiency and thermal management issues. So you'll need to run prime movers anyway. Megayachts that run gensets 24/7 spend the money on vibration and noise damping.....

[CalmSeasQuest]

Originally Posted by Capdave360

This is really fun. It will probably more or less work, though not without some adjustments and some quirks. BTW I've used 24V 250A Electrodyne alternators - great machines.

All that said, if what you really wanted out of all this most of all is reliable 24/7 air conditioning, this is dramatic overkill. For a fraction of the mass, volume, and cost you could have double elastic mounted and double cocooned a generator, stripped the water off to keep the exhaust quiet, and it would be waaaaaaay less complex and waaaaaay more reliable. You probably could have done it twice - once each side - and still be under 50% of the cost. But it is a really fun experiment....

In the end you have to feed the aircons. The solar panels won't run 60KBTU regardless of how much you buffer with storage, and your system will have really significant efficiency and thermal management issues. So you'll need to run prime movers anyway. Megayachts that run gensets 24/7 spend the money on vibration and noise damping.....

Thanks but the last thing I’m looking for is another Genset. My goal is to minimize dependence an diesel generation and the corresponding maintenance. We don’t need 60KBTU of AirCon, the system was sized to drive 20KBTU or less. Based on my load study, it should be more than sufficient for our intended purposes.

I’m curious; what do you mean “more or less work” and what “quirks” do you see in the design?

[nebster]

Well, we run exactly 60kBTU of air off a similar setup, except with a much larger battery and the convenience of being on shore power to recharge it sometimes.

It’s true, though, that eventually the genset has to spin up. But for less time and at a much higher duty while it is on, thankfully. (We spent a lot to quieten it, too.)

[Palarran]

It sounds like an impressive system. If you don't mind explaining, why do you need so much inverter/charger capacity and for that matter, so much of the other stuff. Why do the 12 volt bank and 24 volt bank? I ask as I have worked towards the opposite of what you are doing and am constantly removing stuff and working towards a simple - simple - simple system.

I had a 12kva and 8kva Northern Lights. I removed the 12 already and am thinking about replacing the 8 with a 6kva. I have 1350 watts of solar through 3 Victron charge controllers that feed a 1050 amp hour bank. This bank starts the starboard engine and generator directly and there is one small battery for the port engine. I also have an Autotransformer and 32amp Iso transformer but haven't used them since leaving the Med. My inverter is a Victron 3000 watt.

This takes care of the boat totally except for my water maker (11 amps) and air conditioners (12amps). The solar charges the batteries completely unless there is a long stretch of bad cloud cover. The batteries only discharge 30% and are typically recharged by noon. To be clear though, when cruising we do typically run the generator for two hours per day to make water and heat it if the engines didn't run.

Do you actually have 9 tons of A/C or is it 18? That seems like an incredible amount as we right now have 6 and will replace it with 4 tons in November.

[Capdave360]

Originally Posted by CalmSeasQuest

Thanks but the last thing I’m looking for is another Genset. My goal is to minimize dependence an diesel generation and the corresponding maintenance. We don’t need 60KBTU of AirCon, the system was sized to drive 20KBTU or less. Based on my load study, it should be more than sufficient for our intended purposes.

I’m curious; what do you mean “more or less work” and what “quirks” do you see in the design?

Tom - if you subtract the energy your batteries actually store from the solar panels from the energy that you pull from the batteries to run all your systems, you have to make up the difference somehow - shorepower or a prime mover. There are inefficiencies storing energy in the battery, and inefficiencies delivering stored energy to the consumers. Those inefficiencies manifest as heat; sometimes distributed in wiring and junctions, sometimes concentrated in devices. The hotter everything gets the less efficient it is the more heat it makes, a negative spiral. It's not clear your system design has really accounted for this thermal aspect. The net result is a bigger gap than thought between solar panel nameplate and consumers nameplate - i.e., more shorepower or prime mover.

You have a lot of components with a lot of connections and a lot of software. Despite being mostly (all?) Victron, there will be glitches, both hardware and software. This is not a maintenance free system, it's going to eat a fair amount of your time, and you still will have generator maintenance for the reasons above.

The "mostly works" depends on the magnitude and frequency of the glitches, and also reflects on your (apparently) prime objective of reducing generator hours. Remember things break sitting unused too, and the calendar counts as much as operating hours for some things.

The quirks aren't your system design - it's the difference between how the system actually functions compared to how it was designed to function. Rarely the same thing in a system of this complexity.

For context I helped design an electric hybrid power system on a megayacht ketch 15 years ago, the first such example. We built what was then the third largest lithium ion battery in existence to peak buffer smaller generators sized to energy instead of power, to provide AirCon overnight without generators, and to provide low speed propulsion through inline motor-generators. In practice the goal it met best was buffering the generators, which you couldn't actually hear or feel running at all. 15 years later it continues to be a high maintenance and sometimes glitchy system.

Hope this helps.

[CalmSeasQuest]

Originally Posted by Palarran

It sounds like an impressive system. If you don't mind explaining, why do you need so much inverter/charger capacity and for that matter, so much of the other stuff. Why do the 12 volt bank and 24 volt bank? I ask as I have worked towards the opposite of what you are doing and am constantly removing stuff and working towards a simple - simple - simple system.

Do you actually have 9 tons of A/C or is it 18? That seems like an incredible amount as we right now have 6 and will replace it with 4 tons in November.

Hi Palarran,

Our inverter capacity is somewhat over-sized. It provides 220V capacity to run multiple AirCons for a short period of time to quickly cool the boat if desired. We can also make water at 180L/h on batteries should it be needed. Another consideration was battery charging. The combined MultiPlus chargers provide 280A @24V (6720W) to the batteries. Lastly, we will have some thermal degradation as the Multis are located in the Port engine well.

A single bank presented a single point of failure that I could not accept. Splitting the banks was solely driven by a demand for fail-over. Should the BMS shut down the either bank, all critical systems continue to run. I addressed this in more detail in the original post.

We do have 60KBTU (breakdown in the original post), although we rarely use more then 20KBTU for any extended period of time.

[CalmSeasQuest]

Originally Posted by Capdave360

Tom - if you subtract the energy your batteries actually store from the solar panels from the energy that you pull from the batteries to run all your systems, you have to make up the difference somehow - shorepower or a prime mover. There are inefficiencies storing energy in the battery, and inefficiencies delivering stored energy to the consumers. Those inefficiencies manifest as heat; sometimes distributed in wiring and junctions, sometimes concentrated in devices. The hotter everything gets the less efficient it is the more heat it makes, a negative spiral. It's not clear your system design has really accounted for this thermal aspect. The net result is a bigger gap than thought between solar panel nameplate and consumers nameplate - i.e., more shorepower or prime mover.

You have a lot of components with a lot of connections and a lot of software. Despite being mostly (all?) Victron, there will be glitches, both hardware and software. This is not a maintenance free system, it's going to eat a fair amount of your time, and you still will have generator maintenance for the reasons above.

The "mostly works" depends on the magnitude and frequency of the glitches, and also reflects on your (apparently) prime objective of reducing generator hours. Remember things break sitting unused too, and the calendar counts as much as operating hours for some things.

The quirks aren't your system design - it's the difference between how the system actually functions compared to how it was designed to function. Rarely the same thing in a system of this complexity.

For context I helped design an electric hybrid power system on a megayacht ketch 15 years ago, the first such example. We built what was then the third largest lithium ion battery in existence to peak buffer smaller generators sized to energy instead of power, to provide AirCon overnight without generators, and to provide low speed propulsion through inline motor-generators. In practice the goal it met best was buffering the generators, which you couldn't actually hear or feel running at all. 15 years later it continues to be a high maintenance and sometimes glitchy system.

Hope this helps.

Thanks Capdave, that was very helpful. Thank you for taking the time.

I agree and accept that with heavy AirCon use the Genset is still needed. I'm hoping the auto-start functionality will make this more efficient (i.e. higher output, always bulking, start stop if/when needed with minimal user intervention...) I also think we'll be able to add ~600W of additional solar to further reduce Genset hours.

To those that have commented on the cost, or questioned the need for such a system...

I have a daughter with special needs (Down Syndrome). Cooling is a critical medical need that without; would render my cruising plans impossible. With that said, I did an amortization calculation to see how many years it would take to recover the costs of the system taking into account total Genset costs, (depreciation, Mx, fuel...)

Let's just say I'm committed to living a very looong life to recoup the costs

[Palarran]

Originally Posted by CalmSeasQuest

Hi Palarran,


We do have 20KBTU, although we rarely use more then 20KBTU for any extended period of time.

Ok.

I don't know if you are quoting the cooling right or not but 20,000 btu's is a little more than 1.5 ton's of cooling. There are 12,000 btu's per ton.

Just remember weight is the performance killer with ALL catamarans. If the choice was non-critical redundancy at the expense of added weight and complexity, I'll chose to go without the backup.

[CalmSeasQuest]

Originally Posted by Palarran

Ok.

I don't know if you are quoting the cooling right or not but 20,000 btu's is a little more than 1.5 ton's of cooling. There are 12,000 btu's per ton.

Just remember weight is the performance killer with ALL catamarans. If the choice was non-critical redundancy at the expense of added weight and complexity, I'll chose to go without the backup.

(I see what happened, I corrected a typo (60K total, not 20K) but after you had copied it)

I took the cooling specs directly for the Dometic units installed - We have a combination of 8K and 12K BTU units totally 60K BTU. If my math is correct that's 5t of total cooling.

I agree weight is a concern and try to make every decision "weighing" the pros and cons. That said; I long ago accepted the "CondoCat" moniker.

[Palarran]

Originally Posted by CalmSeasQuest

I long ago accepted the "CondoCat" moniker.

You ever notice that the people who use the term CondoCat either don't have a boat or don't have a wife?

[Frode]

Fascinating system, Tom. Very interested to see how it all turns out. My setup is much smaller than yours, at roughly 12kWh of LiFePO4 capacity, at 12V. Currently charged from 1.6kW of solar, with an intended expansion to 2.2kW. I use Lensun's flexible panels, with SunPower's Maxeon III cells. Since I'm not yet running the 36kBTU AirCon, solar is plenty adequate.

I have, waiting to be finalized, a custom made AC battery charger, consisting of 5x2.3kW units in parallell, for a total of 11.5kW - well matched to the 12kW Northern Lights gen. This will allow just over 800 amps into the bank, near 1C, and is only intended used for long periods of diminished insolation.

Not happy with Victron's BMS nor certain other parts of their control system, I run the Venus OS as a gateway to a Signal K based control and reporting system. My EMS (Energy Management System) is entirely self designed and implemented. Not a suggested approach unless you have deep technical insights.

Don't know how your 20-year-newer saloon compares to mine, but I found an excellent alcove behind the cabinets where battery bank and inverters are installed. There's no technical equipment left in the tails nor engine compartments. Engine and genset starters are fed by a DC bus (whole vessel), which is locally buffered by ultracapacitor banks (one in each tail), capable of delivering a thousand amps easily.

[CalmSeasQuest]

Originally Posted by Frode

Fascinating system, Tom. Very interested to see how it all turns out. My setup is much smaller than yours, at roughly 12kWh of LiFePO4 capacity, at 12V. Currently charged from 1.6kW of solar, with an intended expansion to 2.2kW. I use Lensun's flexible panels, with SunPower's Maxeon III cells. Since I'm not yet running the 36kBTU AirCon, solar is plenty adequate.

I have, waiting to be finalized, a custom made AC battery charger, consisting of 5x2.3kW units in parallell, for a total of 11.5kW - well matched to the 12kW Northern Lights gen. This will allow just over 800 amps into the bank, near 1C, and is only intended used for long periods of diminished insolation.

Not happy with Victron's BMS nor certain other parts of their control system, I run the Venus OS as a gateway to a Signal K based control and reporting system. My EMS (Energy Management System) is entirely self designed and implemented. Not a suggested approach unless you have deep technical insights.

Don't know how your 20-year-newer saloon compares to mine, but I found an excellent alcove behind the cabinets where battery bank and inverters are installed. There's no technical equipment left in the tails nor engine compartments. Engine and genset starters are fed by a DC bus (whole vessel), which is locally buffered by ultracapacitor banks (one in each tail), capable of delivering a thousand amps easily.

Thanks Frode,

That sounds like an amazing setup, especially the use of ultracapacitors. I was also disappointed in how the Victron BMS handles a cell or battery fault, i.e. shutting down an entire paralleled bank rather than shutting the the offending battery. I even looked into using an individual BMS per battery but was told Victron did not support multiple BMS/bank.

[daydreamer]

One comment on additional solar on the port side.

If you are in the Caribbean, the wind is nearly always from the east (plus or minus). At anchor your port side will be facing north and get a lot less useful sun than the starboard side, which will be facing south. The rack over the davits will be unaffected, but on the bimini, a negative angle or shadow from the boom could have a big effect.

Also, in the afternoon while at anchor, our starboard engine room is much warmer than our port ER. That's solar power, want it or not!

[Capdave360]

Originally Posted by daydreamer

One comment on additional solar on the port side.

If you are in the Caribbean, the wind is nearly always from the east (plus or minus). At anchor your port side will be facing north and get a lot less useful sun than the starboard side, which will be facing south. The rack over the davits will be unaffected, but on the bimini, a negative angle or shadow from the boom could have a big effect.

Also, in the afternoon while at anchor, our starboard engine room is much warmer than our port ER. That's solar power, want it or not!

This is certainly true in the Northern hemisphere winter. But here in Grenada the sun went North of us on April 21, and won't go south of us again until Friday. Been kind of funny watching people put their booms to the North by rote, and not checking the actual effect.....

[Rorzech]

Originally Posted by CalmSeasQuest

Thanks Capdave, that was very helpful. Thank you for taking the time.

I agree and accept that with heavy AirCon use the Genset is still needed. I'm hoping the auto-start functionality will make this more efficient (i.e. higher output, always bulking, start stop if/when needed with minimal user intervention...) I also think we'll be able to add ~600W of additional solar to further reduce Genset hours.

Let's just say I'm committed to living a very looong life to recoup the costs

I think you would be happier with 1,600 watts additional solar & a BMV-712 Smart Victron monitor. Just sayin'. You have a great system !