31.2Kw Victron LiFePO4 Split System Install

[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.

[Brian Pokosh]

Are you using isolation transformers while on shore power?

[barnakiel]

Is the alternator secured from the battery sudden switch off ?


Alternators hate being connected to 'nothing'.



b.

[CalmSeasQuest]

Originally Posted by Brian Pokosh

Are you using isolation transformers while on shore power?

Hi Brian,

No Isolation Transformer, we used a DEI Galvanic Isolator and a Victron 100A AutoTransformer to prevent an unbalanced 115V leg when on GenSet or shore power.

[Statistical]

Impressive setup and gorgeous boat.

Is there a reason you went with a seperate 12V battery bank instead of using Victron DC to DC converts to supply 12V panel from the 24V bank?

[CalmSeasQuest]

Originally Posted by barnakiel

Is the alternator secured from the battery sudden switch off ?


Alternators hate being connected to 'nothing'.



b.

Hi Barnakie,

Yes, we took a multi-pronged approach. Although I'm a but fuzzy on the exact process, the Victron BMS communicates with the alternator and "should" shut it down in the even of a BMS battery shutdown. There may also be also some protective functionality in the Wakespeed external regulators as they also measure flow into the battery banks.

As a fail-safe, we used Sterling Alternator Protects on both alternators.

[CalmSeasQuest]

Originally Posted by Statistical

Impressive setup and gorgeous boat.

Is there a reason you went with a seperate 12V battery bank instead of using Victron DC to DC converts to supply 12V panel from the 24V bank?

Thanks!

Yes, fail-over, I couldn't accept the boat going dark should the BMS shut down the battery bank - Especially as this will be the high-load bank (although non-critical loads) and is more likely to encounter a low SOC condition.

This method provides many hours of continued operation on the 600AH 12V bank providing time to address whatever caused the 24V shutdown. This is especially important because the Victron BMS requires all cells to be recharged to 3.2V before the it brings the bank back online. In a low voltage shutdown scenario, even with all our charging capacity, it will take hours to recharge a 1000AH 24V bank.

[Brian Pokosh]

Originally Posted by CalmSeasQuest

Hi Brian,

No Isolation Transformer, we used a DEI Galvanic Isolator and a Victron 100A AutoTransformer to prevent an unbalanced 115V leg when on GenSet or shore power.

I’m familiar with the Autotransformer, and use one after a 230V Multiplus to get 115V power.

Have you had the boat on shore power long enough to determine whether the galvanic isolator is doing the job?

[CalmSeasQuest]

I installed the isolator on delivery in 1/2019. The only observation I have is that having spent a lot of time in marinas (unfortunately), our GenSet, SailDrive and Prop zincs are lasting longer than anticipated.

Although it’s difficult to quantify; I’d like to think the isolator is “earning it’s keep”.

[barnakiel]

Originally Posted by CalmSeasQuest

Hi Barnakie,

Yes, we took a multi-pronged approach. Although I'm a but fuzzy on the exact process, the Victron BMS communicates with the alternator and "should" shut it down in the even of a BMS battery shutdown. There may also be also some protective functionality in the Wakespeed external regulators as they also measure flow into the battery banks.

As a fail-safe, we used Sterling Alternator Protects on both alternators.

OK.


Same attitude here.


b.

[Brian Pokosh]

Originally Posted by CalmSeasQuest

I installed the isolator on delivery in 1/2019. The only observation I have is that having spent a lot of time in marinas (unfortunately), our GenSet, SailDrive and Prop zincs are lasting longer than anticipated.

Although it’s difficult to quantify; I’d like to think the isolator is “earning it’s keep”.

The alternative would be a full isolation transformer and for your 50A/12kW of charging you’d be looking at a rather large and heavy piece of equipment.

Termodinamica makes a 24VDC air conditioner that would have been a good fit for your system. Did you consider DC units or were they all factory installed?

[CalmSeasQuest]

I quashed the thought of an isolation transformer early on due to space and weight considerations. I was trying to avoid the AutoTransformer as well, but couldn’t solve the unbalanced leg problem gracefully.

Our AirCons are factory installed Dometics, so we had no say in the choice. That said; they perform well - especially since installing the soft starts.

[barnakiel]

Have a good look at the line:


genset > charger > lifepo


The charger part needs to be sized on the upper end of the available spectrum to maximise the benefit of lifepo (= to shorten genset run times).


barnakiel

[CalmSeasQuest]

Originally Posted by barnakiel

Have a good look at the line:

genset > charger > lifepo

The charger part needs to be sized on the upper end of the available spectrum to maximise the benefit of lifepo (= to shorten genset run times).

barnakiel

Like all designs, the balance between storage and generation has been a challenge. The current 1850W of solar will be woefully inadequate. I'm considering adding another ~600W of flexible panels to the Port side coach roof but they and the exposed wiring is at best "unsightly".

As for charging, I think were in pretty good shape. The 4 Multiplus chargers collectively put out 280AH @ 24V (6720W). Assuming 80% DOD, the 13.5Kw GenSet should be able to get the 24V bank back to ~95% in less than 3 hours.

Lastly, more 24V LiFePO4 would be great, but it becomes impractical due to space/weight limitations (and $$$) and with the finite solar, would simply result in more Genset hours to maintain.

[Matt Johnson]

I wish I were your Victron dealer That's an awesome set-up!

Matt